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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 

How to write a good literature review 

• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• How to write a literature review faster with Paperpal? 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

1. Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 

2. Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 

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3. Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 

4. Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 

5. Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 

6. Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

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Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

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Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

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The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a good literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. By combining effortless research with an easy citation process, Paperpal Research streamlines the literature review process and empowers you to write faster and with more confidence. Try Paperpal Research now and see for yourself.  

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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• UConn Library
• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
• << Previous: Getting Started
• Next: How to Pick a Topic >>
• Last Updated: Sep 21, 2022 2:16 PM
• URL: https://guides.lib.uconn.edu/literaturereview

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• Knowledge Base
• Dissertation
• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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• University of Texas Libraries

Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

Reference management. Clean and simple.

What is a literature review? [with examples]

What is a literature review?

The purpose of a literature review, how to write a literature review, the format of a literature review, general formatting rules, the length of a literature review, literature review examples, frequently asked questions about literature reviews, related articles.

A literature review is an assessment of the sources in a chosen topic of research.

In a literature review, you’re expected to report on the existing scholarly conversation, without adding new contributions.

If you are currently writing one, you've come to the right place. In the following paragraphs, we will explain:

• the objective of a literature review
• how to write a literature review
• the basic format of a literature review

Tip: It’s not always mandatory to add a literature review in a paper. Theses and dissertations often include them, whereas research papers may not. Make sure to consult with your instructor for exact requirements.

The four main objectives of a literature review are:

• Studying the references of your research area
• Summarizing the main arguments
• Identifying current gaps, stances, and issues
• Presenting all of the above in a text

Ultimately, the main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

The format of a literature review is fairly standard. It includes an:

• introduction that briefly introduces the main topic
• body that includes the main discussion of the key arguments
• conclusion that highlights the gaps and issues of the literature

➡️ Take a look at our guide on how to write a literature review to learn more about how to structure a literature review.

First of all, a literature review should have its own labeled section. You should indicate clearly in the table of contents where the literature can be found, and you should label this section as “Literature Review.”

➡️ For more information on writing a thesis, visit our guide on how to structure a thesis .

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, it will be long. If your paper does not depend entirely on references, it will be short.

Take a look at these three theses featuring great literature reviews:

• School-Based Speech-Language Pathologist's Perceptions of Sensory Food Aversions in Children [ PDF , see page 20]
• Who's Writing What We Read: Authorship in Criminological Research [ PDF , see page 4]
• A Phenomenological Study of the Lived Experience of Online Instructors of Theological Reflection at Christian Institutions Accredited by the Association of Theological Schools [ PDF , see page 56]

Literature reviews are most commonly found in theses and dissertations. However, you find them in research papers as well.

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, then it will be long. If your paper does not depend entirely on references, then it will be short.

No. A literature review should have its own independent section. You should indicate clearly in the table of contents where the literature review can be found, and label this section as “Literature Review.”

The main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

How to Write a Literature Review

What is a literature review.

• What Is the Literature
• Writing the Review

A literature review is much more than an annotated bibliography or a list of separate reviews of articles and books. It is a critical, analytical summary and synthesis of the current knowledge of a topic. Thus it should compare and relate different theories, findings, etc, rather than just summarize them individually. In addition, it should have a particular focus or theme to organize the review. It does not have to be an exhaustive account of everything published on the topic, but it should discuss all the significant academic literature and other relevant sources important for that focus.

This is meant to be a general guide to writing a literature review: ways to structure one, what to include, how it supplements other research. For more specific help on writing a review, and especially for help on finding the literature to review, sign up for a Personal Research Session .

The specific organization of a literature review depends on the type and purpose of the review, as well as on the specific field or topic being reviewed. But in general, it is a relatively brief but thorough exploration of past and current work on a topic. Rather than a chronological listing of previous work, though, literature reviews are usually organized thematically, such as different theoretical approaches, methodologies, or specific issues or concepts involved in the topic. A thematic organization makes it much easier to examine contrasting perspectives, theoretical approaches, methodologies, findings, etc, and to analyze the strengths and weaknesses of, and point out any gaps in, previous research. And this is the heart of what a literature review is about. A literature review may offer new interpretations, theoretical approaches, or other ideas; if it is part of a research proposal or report it should demonstrate the relationship of the proposed or reported research to others' work; but whatever else it does, it must provide a critical overview of the current state of research efforts. 

Literature reviews are common and very important in the sciences and social sciences. They are less common and have a less important role in the humanities, but they do have a place, especially stand-alone reviews.

Types of Literature Reviews

There are different types of literature reviews, and different purposes for writing a review, but the most common are:

• Stand-alone literature review articles . These provide an overview and analysis of the current state of research on a topic or question. The goal is to evaluate and compare previous research on a topic to provide an analysis of what is currently known, and also to reveal controversies, weaknesses, and gaps in current work, thus pointing to directions for future research. You can find examples published in any number of academic journals, but there is a series of Annual Reviews of *Subject* which are specifically devoted to literature review articles. Writing a stand-alone review is often an effective way to get a good handle on a topic and to develop ideas for your own research program. For example, contrasting theoretical approaches or conflicting interpretations of findings can be the basis of your research project: can you find evidence supporting one interpretation against another, or can you propose an alternative interpretation that overcomes their limitations?
• Part of a research proposal . This could be a proposal for a PhD dissertation, a senior thesis, or a class project. It could also be a submission for a grant. The literature review, by pointing out the current issues and questions concerning a topic, is a crucial part of demonstrating how your proposed research will contribute to the field, and thus of convincing your thesis committee to allow you to pursue the topic of your interest or a funding agency to pay for your research efforts.
• Part of a research report . When you finish your research and write your thesis or paper to present your findings, it should include a literature review to provide the context to which your work is a contribution. Your report, in addition to detailing the methods, results, etc. of your research, should show how your work relates to others' work.

A literature review for a research report is often a revision of the review for a research proposal, which can be a revision of a stand-alone review. Each revision should be a fairly extensive revision. With the increased knowledge of and experience in the topic as you proceed, your understanding of the topic will increase. Thus, you will be in a better position to analyze and critique the literature. In addition, your focus will change as you proceed in your research. Some areas of the literature you initially reviewed will be marginal or irrelevant for your eventual research, and you will need to explore other areas more thoroughly. 

Examples of Literature Reviews

See the series of Annual Reviews of *Subject* which are specifically devoted to literature review articles to find many examples of stand-alone literature reviews in the biomedical, physical, and social sciences. 

Research report articles vary in how they are organized, but a common general structure is to have sections such as:

• Abstract - Brief summary of the contents of the article
• Introduction - A explanation of the purpose of the study, a statement of the research question(s) the study intends to address
• Literature review - A critical assessment of the work done so far on this topic, to show how the current study relates to what has already been done
• Methods - How the study was carried out (e.g. instruments or equipment, procedures, methods to gather and analyze data)
• Results - What was found in the course of the study
• Discussion - What do the results mean
• Conclusion - State the conclusions and implications of the results, and discuss how it relates to the work reviewed in the literature review; also, point to directions for further work in the area

Here are some articles that illustrate variations on this theme. There is no need to read the entire articles (unless the contents interest you); just quickly browse through to see the sections, and see how each section is introduced and what is contained in them.

The Determinants of Undergraduate Grade Point Average: The Relative Importance of Family Background, High School Resources, and Peer Group Effects , in The Journal of Human Resources , v. 34 no. 2 (Spring 1999), p. 268-293.

This article has a standard breakdown of sections:

• Introduction
• Literature Review
• Some discussion sections

First Encounters of the Bureaucratic Kind: Early Freshman Experiences with a Campus Bureaucracy , in The Journal of Higher Education , v. 67 no. 6 (Nov-Dec 1996), p. 660-691.

This one does not have a section specifically labeled as a "literature review" or "review of the literature," but the first few sections cite a long list of other sources discussing previous research in the area before the authors present their own study they are reporting.

• Next: What Is the Literature >>
• Last Updated: Jan 11, 2024 9:48 AM
• URL: https://libguides.wesleyan.edu/litreview

How To Write An A-Grade Literature Review

3 straightforward steps (with examples) + free template.

By: Derek Jansen (MBA) | Expert Reviewed By: Dr. Eunice Rautenbach | October 2019

Quality research is about building onto the existing work of others , “standing on the shoulders of giants”, as Newton put it. The literature review chapter of your dissertation, thesis or research project is where you synthesise this prior work and lay the theoretical foundation for your own research.

Long story short, this chapter is a pretty big deal, which is why you want to make sure you get it right . In this post, I’ll show you exactly how to write a literature review in three straightforward steps, so you can conquer this vital chapter (the smart way).

Overview: The Literature Review Process

• Understanding the “ why “
• Finding the relevant literature
• Cataloguing and synthesising the information
• Outlining & writing up your literature review
• Example of a literature review

But first, the “why”…

Before we unpack how to write the literature review chapter, we’ve got to look at the why . To put it bluntly, if you don’t understand the function and purpose of the literature review process, there’s no way you can pull it off well. So, what exactly is the purpose of the literature review?

Well, there are (at least) four core functions:

• For you to gain an understanding (and demonstrate this understanding) of where the research is at currently, what the key arguments and disagreements are.
• For you to identify the gap(s) in the literature and then use this as justification for your own research topic.
• To help you build a conceptual framework for empirical testing (if applicable to your research topic).
• To inform your methodological choices and help you source tried and tested questionnaires (for interviews ) and measurement instruments (for surveys ).

Most students understand the first point but don’t give any thought to the rest. To get the most from the literature review process, you must keep all four points front of mind as you review the literature (more on this shortly), or you’ll land up with a wonky foundation.

Okay – with the why out the way, let’s move on to the how . As mentioned above, writing your literature review is a process, which I’ll break down into three steps:

• Finding the most suitable literature
• Understanding , distilling and organising the literature
• Planning and writing up your literature review chapter

Importantly, you must complete steps one and two before you start writing up your chapter. I know it’s very tempting, but don’t try to kill two birds with one stone and write as you read. You’ll invariably end up wasting huge amounts of time re-writing and re-shaping, or you’ll just land up with a disjointed, hard-to-digest mess . Instead, you need to read first and distil the information, then plan and execute the writing.

Step 1: Find the relevant literature

Naturally, the first step in the literature review journey is to hunt down the existing research that’s relevant to your topic. While you probably already have a decent base of this from your research proposal , you need to expand on this substantially in the dissertation or thesis itself.

Essentially, you need to be looking for any existing literature that potentially helps you answer your research question (or develop it, if that’s not yet pinned down). There are numerous ways to find relevant literature, but I’ll cover my top four tactics here. I’d suggest combining all four methods to ensure that nothing slips past you:

Method 1 – Google Scholar Scrubbing

Google’s academic search engine, Google Scholar , is a great starting point as it provides a good high-level view of the relevant journal articles for whatever keyword you throw at it. Most valuably, it tells you how many times each article has been cited, which gives you an idea of how credible (or at least, popular) it is. Some articles will be free to access, while others will require an account, which brings us to the next method.

Method 2 – University Database Scrounging

Generally, universities provide students with access to an online library, which provides access to many (but not all) of the major journals.

So, if you find an article using Google Scholar that requires paid access (which is quite likely), search for that article in your university’s database – if it’s listed there, you’ll have access. Note that, generally, the search engine capabilities of these databases are poor, so make sure you search for the exact article name, or you might not find it.

Method 3 – Journal Article Snowballing

At the end of every academic journal article, you’ll find a list of references. As with any academic writing, these references are the building blocks of the article, so if the article is relevant to your topic, there’s a good chance a portion of the referenced works will be too. Do a quick scan of the titles and see what seems relevant, then search for the relevant ones in your university’s database.

Method 4 – Dissertation Scavenging

Similar to Method 3 above, you can leverage other students’ dissertations. All you have to do is skim through literature review chapters of existing dissertations related to your topic and you’ll find a gold mine of potential literature. Usually, your university will provide you with access to previous students’ dissertations, but you can also find a much larger selection in the following databases:

• Open Access Theses & Dissertations
• Stanford SearchWorks

Keep in mind that dissertations and theses are not as academically sound as published, peer-reviewed journal articles (because they’re written by students, not professionals), so be sure to check the credibility of any sources you find using this method. You can do this by assessing the citation count of any given article in Google Scholar. If you need help with assessing the credibility of any article, or with finding relevant research in general, you can chat with one of our Research Specialists .

Alright – with a good base of literature firmly under your belt, it’s time to move onto the next step.

Need a helping hand?

Step 2: Log, catalogue and synthesise

Once you’ve built a little treasure trove of articles, it’s time to get reading and start digesting the information – what does it all mean?

While I present steps one and two (hunting and digesting) as sequential, in reality, it’s more of a back-and-forth tango – you’ll read a little , then have an idea, spot a new citation, or a new potential variable, and then go back to searching for articles. This is perfectly natural – through the reading process, your thoughts will develop , new avenues might crop up, and directional adjustments might arise. This is, after all, one of the main purposes of the literature review process (i.e. to familiarise yourself with the current state of research in your field).

As you’re working through your treasure chest, it’s essential that you simultaneously start organising the information. There are three aspects to this:

• Logging reference information
• Building an organised catalogue
• Distilling and synthesising the information

I’ll discuss each of these below:

2.1 – Log the reference information

As you read each article, you should add it to your reference management software. I usually recommend Mendeley for this purpose (see the Mendeley 101 video below), but you can use whichever software you’re comfortable with. Most importantly, make sure you load EVERY article you read into your reference manager, even if it doesn’t seem very relevant at the time.

2.2 – Build an organised catalogue

In the beginning, you might feel confident that you can remember who said what, where, and what their main arguments were. Trust me, you won’t. If you do a thorough review of the relevant literature (as you must!), you’re going to read many, many articles, and it’s simply impossible to remember who said what, when, and in what context . Also, without the bird’s eye view that a catalogue provides, you’ll miss connections between various articles, and have no view of how the research developed over time. Simply put, it’s essential to build your own catalogue of the literature.

I would suggest using Excel to build your catalogue, as it allows you to run filters, colour code and sort – all very useful when your list grows large (which it will). How you lay your spreadsheet out is up to you, but I’d suggest you have the following columns (at minimum):

• Author, date, title – Start with three columns containing this core information. This will make it easy for you to search for titles with certain words, order research by date, or group by author.
• Categories or keywords – You can either create multiple columns, one for each category/theme and then tick the relevant categories, or you can have one column with keywords.
• Key arguments/points – Use this column to succinctly convey the essence of the article, the key arguments and implications thereof for your research.
• Context – Note the socioeconomic context in which the research was undertaken. For example, US-based, respondents aged 25-35, lower- income, etc. This will be useful for making an argument about gaps in the research.
• Methodology – Note which methodology was used and why. Also, note any issues you feel arise due to the methodology. Again, you can use this to make an argument about gaps in the research.
• Quotations – Note down any quoteworthy lines you feel might be useful later.
• Notes – Make notes about anything not already covered. For example, linkages to or disagreements with other theories, questions raised but unanswered, shortcomings or limitations, and so forth.

If you’d like, you can try out our free catalog template here (see screenshot below).

2.3 – Digest and synthesise

Most importantly, as you work through the literature and build your catalogue, you need to synthesise all the information in your own mind – how does it all fit together? Look for links between the various articles and try to develop a bigger picture view of the state of the research. Some important questions to ask yourself are:

• What answers does the existing research provide to my own research questions ?
• Which points do the researchers agree (and disagree) on?
• How has the research developed over time?
• Where do the gaps in the current research lie?

To help you develop a big-picture view and synthesise all the information, you might find mind mapping software such as Freemind useful. Alternatively, if you’re a fan of physical note-taking, investing in a large whiteboard might work for you.

Step 3: Outline and write it up!

Once you’re satisfied that you have digested and distilled all the relevant literature in your mind, it’s time to put pen to paper (or rather, fingers to keyboard). There are two steps here – outlining and writing:

3.1 – Draw up your outline

Having spent so much time reading, it might be tempting to just start writing up without a clear structure in mind. However, it’s critically important to decide on your structure and develop a detailed outline before you write anything. Your literature review chapter needs to present a clear, logical and an easy to follow narrative – and that requires some planning. Don’t try to wing it!

Naturally, you won’t always follow the plan to the letter, but without a detailed outline, you’re more than likely going to end up with a disjointed pile of waffle , and then you’re going to spend a far greater amount of time re-writing, hacking and patching. The adage, “measure twice, cut once” is very suitable here.

In terms of structure, the first decision you’ll have to make is whether you’ll lay out your review thematically (into themes) or chronologically (by date/period). The right choice depends on your topic, research objectives and research questions, which we discuss in this article .

Once that’s decided, you need to draw up an outline of your entire chapter in bullet point format. Try to get as detailed as possible, so that you know exactly what you’ll cover where, how each section will connect to the next, and how your entire argument will develop throughout the chapter. Also, at this stage, it’s a good idea to allocate rough word count limits for each section, so that you can identify word count problems before you’ve spent weeks or months writing!

PS – check out our free literature review chapter template…

3.2 – Get writing

With a detailed outline at your side, it’s time to start writing up (finally!). At this stage, it’s common to feel a bit of writer’s block and find yourself procrastinating under the pressure of finally having to put something on paper. To help with this, remember that the objective of the first draft is not perfection – it’s simply to get your thoughts out of your head and onto paper, after which you can refine them. The structure might change a little, the word count allocations might shift and shuffle, and you might add or remove a section – that’s all okay. Don’t worry about all this on your first draft – just get your thoughts down on paper.

Once you’ve got a full first draft (however rough it may be), step away from it for a day or two (longer if you can) and then come back at it with fresh eyes. Pay particular attention to the flow and narrative – does it fall fit together and flow from one section to another smoothly? Now’s the time to try to improve the linkage from each section to the next, tighten up the writing to be more concise, trim down word count and sand it down into a more digestible read.

Once you’ve done that, give your writing to a friend or colleague who is not a subject matter expert and ask them if they understand the overall discussion. The best way to assess this is to ask them to explain the chapter back to you. This technique will give you a strong indication of which points were clearly communicated and which weren’t. If you’re working with Grad Coach, this is a good time to have your Research Specialist review your chapter.

Finally, tighten it up and send it off to your supervisor for comment. Some might argue that you should be sending your work to your supervisor sooner than this (indeed your university might formally require this), but in my experience, supervisors are extremely short on time (and often patience), so, the more refined your chapter is, the less time they’ll waste on addressing basic issues (which you know about already) and the more time they’ll spend on valuable feedback that will increase your mark-earning potential.

Literature Review Example

In the video below, we unpack an actual literature review so that you can see how all the core components come together in reality.

Let’s Recap

In this post, we’ve covered how to research and write up a high-quality literature review chapter. Let’s do a quick recap of the key takeaways:

• It is essential to understand the WHY of the literature review before you read or write anything. Make sure you understand the 4 core functions of the process.
• The first step is to hunt down the relevant literature . You can do this using Google Scholar, your university database, the snowballing technique and by reviewing other dissertations and theses.
• Next, you need to log all the articles in your reference manager , build your own catalogue of literature and synthesise all the research.
• Following that, you need to develop a detailed outline of your entire chapter – the more detail the better. Don’t start writing without a clear outline (on paper, not in your head!)
• Write up your first draft in rough form – don’t aim for perfection. Remember, done beats perfect.
• Refine your second draft and get a layman’s perspective on it . Then tighten it up and submit it to your supervisor.

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

You Might Also Like:

38 Comments

Thank you very much. This page is an eye opener and easy to comprehend.

This is awesome!

I wish I come across GradCoach earlier enough.

But all the same I’ll make use of this opportunity to the fullest.

Thank you for this good job.

Keep it up!

You’re welcome, Yinka. Thank you for the kind words. All the best writing your literature review.

Thank you for a very useful literature review session. Although I am doing most of the steps…it being my first masters an Mphil is a self study and one not sure you are on the right track. I have an amazing supervisor but one also knows they are super busy. So not wanting to bother on the minutae. Thank you.

You’re most welcome, Renee. Good luck with your literature review 🙂

This has been really helpful. Will make full use of it. 🙂

Thank you Gradcoach.

Really agreed. Admirable effort

thank you for this beautiful well explained recap.

Thank you so much for your guide of video and other instructions for the dissertation writing.

It is instrumental. It encouraged me to write a dissertation now.

Thank you the video was great – from someone that knows nothing thankyou

an amazing and very constructive way of presetting a topic, very useful, thanks for the effort,

It is timely

It is very good video of guidance for writing a research proposal and a dissertation. Since I have been watching and reading instructions, I have started my research proposal to write. I appreciate to Mr Jansen hugely.

I learn a lot from your videos. Very comprehensive and detailed.

Thank you for sharing your knowledge. As a research student, you learn better with your learning tips in research

I was really stuck in reading and gathering information but after watching these things are cleared thanks, it is so helpful.

Really helpful, Thank you for the effort in showing such information

This is super helpful thank you very much.

Thank you for this whole literature writing review.You have simplified the process.

I’m so glad I found GradCoach. Excellent information, Clear explanation, and Easy to follow, Many thanks Derek!

You’re welcome, Maithe. Good luck writing your literature review 🙂

Thank you Coach, you have greatly enriched and improved my knowledge

Great piece, so enriching and it is going to help me a great lot in my project and thesis, thanks so much

This is THE BEST site for ANYONE doing a masters or doctorate! Thank you for the sound advice and templates. You rock!

Thanks, Stephanie 🙂

This is mind blowing, the detailed explanation and simplicity is perfect.

I am doing two papers on my final year thesis, and I must stay I feel very confident to face both headlong after reading this article.

thank you so much.

if anyone is to get a paper done on time and in the best way possible, GRADCOACH is certainly the go to area!

This is very good video which is well explained with detailed explanation

Thank you excellent piece of work and great mentoring

Thanks, it was useful

Thank you very much. the video and the information were very helpful.

Good morning scholar. I’m delighted coming to know you even before the commencement of my dissertation which hopefully is expected in not more than six months from now. I would love to engage my study under your guidance from the beginning to the end. I love to know how to do good job

Thank you so much Derek for such useful information on writing up a good literature review. I am at a stage where I need to start writing my one. My proposal was accepted late last year but I honestly did not know where to start

Like the name of your YouTube implies you are GRAD (great,resource person, about dissertation). In short you are smart enough in coaching research work.

This is a very well thought out webpage. Very informative and a great read.

Very timely.

I appreciate.

Very comprehensive and eye opener for me as beginner in postgraduate study. Well explained and easy to understand. Appreciate and good reference in guiding me in my research journey. Thank you

Thank you. I requested to download the free literature review template, however, your website wouldn’t allow me to complete the request or complete a download. May I request that you email me the free template? Thank you.

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• 04 December 2020
• Correction 09 December 2020

How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

You can also search for this author in PubMed   Google Scholar

Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

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doi: https://doi.org/10.1038/d41586-020-03422-x

Interviews have been edited for length and clarity.

Updates & Corrections

Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

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How to Write a Literature Review

What's a literature review.

• Literature Reviews: A Recap
• Reading Journal Articles
• Does it Describe a Literature Review?
• 1. Identify the Question
• 2. Review Discipline Styles
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• 5. Critically Analyze and Evaluate
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• 7. Write a Literature Review

What's a Literature Review? 

A literature review (or "lit review," for short) is an in-depth critical analysis of published scholarly research related to a specific topic. Published scholarly research (aka, "the literature") may include journal articles, books, book chapters, dissertations and thesis, or conference proceedings. 

A solid lit review must:

• be organized around and related directly to the thesis or research question you're developing
• synthesize results into a summary of what is and is not known
• identify areas of controversy in the literature
• formulate questions that need further research

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

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A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE : Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

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Libraries | Research Guides

Literature reviews, what is a literature review, learning more about how to do a literature review.

• Planning the Review
• The Research Question
• Choosing Where to Search
• Organizing the Review
• Writing the Review

A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. A literature review should address different aspects of a topic as it relates to your research question. A literature review goes beyond a description or summary of the literature you have read. 

• Sage Research Methods Core Collection This link opens in a new window SAGE Research Methods supports research at all levels by providing material to guide users through every step of the research process. SAGE Research Methods is the ultimate methods library with more than 1000 books, reference works, journal articles, and instructional videos by world-leading academics from across the social sciences, including the largest collection of qualitative methods books available online from any scholarly publisher. – Publisher

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• Last Updated: May 2, 2024 10:39 AM
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• Library Homepage

Literature Review: The What, Why and How-to Guide: Literature Reviews?

• Literature Reviews?
• Strategies to Finding Sources
• Keeping up with Research!
• Evaluating Sources & Literature Reviews
• Organizing for Writing
• Writing Literature Review
• Other Academic Writings

What is a Literature Review?

So, what is a literature review .

"A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available or a set of summaries." - Quote from Taylor, D. (n.d)."The Literature Review: A Few Tips on Conducting it".

• Citation: "The Literature Review: A Few Tips on Conducting it"

What kinds of literature reviews are written?

Each field has a particular way to do reviews for academic research literature. In the social sciences and humanities the most common are:

• Narrative Reviews: The purpose of this type of review is to describe the current state of the research on a specific research topic and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weaknesses, and gaps are identified. The review ends with a conclusion section that summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.
• Book review essays/ Historiographical review essays : A type of literature review typical in History and related fields, e.g., Latin American studies. For example, the Latin American Research Review explains that the purpose of this type of review is to “(1) to familiarize readers with the subject, approach, arguments, and conclusions found in a group of books whose common focus is a historical period; a country or region within Latin America; or a practice, development, or issue of interest to specialists and others; (2) to locate these books within current scholarship, critical methodologies, and approaches; and (3) to probe the relation of these new books to previous work on the subject, especially canonical texts. Unlike individual book reviews, the cluster reviews found in LARR seek to address the state of the field or discipline and not solely the works at issue.” - LARR

What are the Goals of Creating a Literature Review?

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 
• Baumeister, R.F. & Leary, M.R. (1997). "Writing narrative literature reviews," Review of General Psychology , 1(3), 311-320.

When do you need to write a Literature Review?

• When writing a prospectus or a thesis/dissertation
• When writing a research paper
• When writing a grant proposal

In all these cases you need to dedicate a chapter in these works to showcase what has been written about your research topic and to point out how your own research will shed new light into a body of scholarship.

Where I can find examples of Literature Reviews?

Note:  In the humanities, even if they don't use the term "literature review", they may have a dedicated  chapter that reviewed the "critical bibliography" or they incorporated that review in the introduction or first chapter of the dissertation, book, or article.

• UCSB electronic theses and dissertations In partnership with the Graduate Division, the UC Santa Barbara Library is making available theses and dissertations produced by UCSB students. Currently included in ADRL are theses and dissertations that were originally filed electronically, starting in 2011. In future phases of ADRL, all theses and dissertations created by UCSB students may be digitized and made available.

Where to Find Standalone Literature Reviews

Literature reviews are also written as standalone articles as a way to survey a particular research topic in-depth. This type of literature review looks at a topic from a historical perspective to see how the understanding of the topic has changed over time. 

• Find e-Journals for Standalone Literature Reviews The best way to get familiar with and to learn how to write literature reviews is by reading them. You can use our Journal Search option to find journals that specialize in publishing literature reviews from major disciplines like anthropology, sociology, etc. Usually these titles are called, "Annual Review of [discipline name] OR [Discipline name] Review. This option works best if you know the title of the publication you are looking for. Below are some examples of these journals! more... less... Journal Search can be found by hovering over the link for Research on the library website.

Social Sciences

• Annual Review of Anthropology
• Annual Review of Political Science
• Annual Review of Sociology
• Ethnic Studies Review

Hard science and health sciences:

• Annual Review of Biomedical Data Science
• Annual Review of Materials Science
• Systematic Review From journal site: "The journal Systematic Reviews encompasses all aspects of the design, conduct, and reporting of systematic reviews" in the health sciences.
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• Last Updated: Mar 5, 2024 11:44 AM
• URL: https://guides.library.ucsb.edu/litreview

Engineering: The Literature Review Process

• How to Use This Guide

What is a literature review and why is it important?

Further reading ....

• 2. Precision vs Retrieval
• 3. Equip Your Tool Box
• 4. What to look for
• 5. Where to Look for it
• 6. How to Look for it
• 7. Keeping Current
• 8. Reading Tips
• 9. Writing Tips
• 10. Checklist

A literature review not only summarizes the knowledge of a particular area or field of study, it also evaluates what has been done, what still needs to be done and why all of this is important to the subject.  

• The Stand-Alone Literature Review A literature review may stand alone as an individual document in which the history of the topic is reported and then analyzed for trends, controversial issues, and what still needs to be studied.  The review could just be a few pages for narrow topics or quite extensive with long bibliographies for in-depth reviews.   In-depth review articles are valuable time-savers for professionals and researchers who need a quick introduction or analysis of a topic but they can be very time-consuming for authors to produce. Examples of review articles:   Walker, Sara Louise (2011)   Building mounted wind turbines and their suitability for the urban scale - a review of methods of estimating urban wind resource .   Energy and Buildings  43(8):1852-1862. For this review, the author focused on the different methodologies used to estimate wind speed in urban settings.  After introducing the theory, she explained the difficulty for in-situ measuring, and then followed up by describing each of the different estimation techniques that have been used instead.  Strengths and weaknesses of each method are discussed and suggestions are given on where more study is needed.   Length: 11 pages. References: 59. Calm, J.M. (2008)   The next generation of refrigerants - historical review, considerations, and outlook.   International Journal of Refrigeration  31(7):1123-1133. This review focuses on the evolution of refrigerants and divides the evolution into 4 generations.  In each generation the author describes which type of refrigerants were most popular and discusses how political, environmental, and economic issues as well as chemical properties effected choices.  Length: 11 pages.  References: 51.  
• The Literature Review as a Section Within a Document Literature reviews are also part of dissertations, theses, research reports and scholarly journal articles; these types of documents include the review in a section or chapter that discusses what has gone before, how the research being presented in this document fills a gap in the field's knowledge and why that is important.   Examples of literature reviews within a journal article:  Jobert, Arthur, et al. (2007) Local acceptance of wind energy: factors of success identified in French and German case studies.  Energy Policy  35(5):2751-2760.  In this case, the literature review is a separate, labeled section appearing between the introduction and methodology sections.  Peel, Deborah and Lloyd, Michael Gregory (2007)   Positive planning for wind-turbines in an urban context.   Local Environment  12(4):343-354. In this case the literature review is incorporated into the article's introduction rather than have its own section.   Which version you choose (separate section or within the introduction) depends on format requirements of the publisher (for journal articles), the ASU Graduate College and your academic unit (for ASU dissertations and theses) and application instructions for grants.   If no format is specified choose the method in which you can best explain your research topic, what has come before and the importance of the knowledge you are adding to the field.    Examples of literature reviews within a dissertation or thesis :  Porter, Wayne Eliot (2011)   Renewable Energy in Rural Southeastern Arizona: Decision Factors: A Comparison of the Consumer Profiles of Homeowners Who Purchased Renewable Energy Systems With Those Who Performed Other Home Upgrades or Remodeling Projects .    Arizona State University, M.S. Thesis.  This author effectively uses a separate chapter for the literature review for his detailed analysis.  Magerman, Beth (2014)   Short-Term Wind Power Forecasts using Doppler Lidar.   Arizona State University, M.S. Thesis. The author puts the literature review within Chapter Two presenting it as part of the background information of her topic.   Note that the literature review within a thesis or dissertation more closely resembles the scope and depth of a stand- alone literature review as opposed to the briefer reviews appearing within journal articles.  Within a thesis or dissertation, the review not only presents the status of research in the specific area it also establishes the author's expertise and justifies his/her own research.   

Online tutorials:

• Literature Reviews: An Overview for Graduate Students Created by the North Caroline State University Libraries

Other ASU Library Guides: 

• Literature Reviews and Annotated Bibliographies More general information about the format and content of literature reviews; created by Ed Oetting, History and Political Science Librarian, Hayden Library. ​

Readings: 

• The Literature Review: A Few Tips on Conducting It Written by Dena Taylor, Health Sciences Writing Centre, University of Toronto
• Literature Reviews Created by The Writing Center at the University of North Carolina, Chapel Hill. 
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• Next: 2. Precision vs Retrieval >>
• Last updated: Jan 2, 2024 8:27 AM
• URL: https://libguides.asu.edu/engineeringlitreview

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Conduct a literature review

What is a literature review.

A literature review is a summary of the published work in a field of study. This can be a section of a larger paper or article, or can be the focus of an entire paper. Literature reviews show that you have examined the breadth of knowledge and can justify your thesis or research questions. They are also valuable tools for other researchers who need to find a summary of that field of knowledge.

Unlike an annotated bibliography, which is a list of sources with short descriptions, a literature review synthesizes sources into a summary that has a thesis or statement of purpose—stated or implied—at its core.

How do I write a literature review?

Step 1: define your research scope.

• What is the specific research question that your literature review helps to define?
• Are there a maximum or minimum number of sources that your review should include?

Ask us if you have questions about refining your topic, search methods, writing tips, or citation management.

Step 2: Identify the literature

Start by searching broadly. Literature for your review will typically be acquired through scholarly books, journal articles, and/or dissertations. Develop an understanding of what is out there, what terms are accurate and helpful, etc., and keep track of all of it with citation management tools . If you need help figuring out key terms and where to search, ask us .

Use citation searching to track how scholars interact with, and build upon, previous research:

• Mine the references cited section of each relevant source for additional key sources
• Use Google Scholar or Scopus to find other sources that have cited a particular work

Step 3: Critically analyze the literature

Key to your literature review is a critical analysis of the literature collected around your topic. The analysis will explore relationships, major themes, and any critical gaps in the research expressed in the work. Read and summarize each source with an eye toward analyzing authority, currency, coverage, methodology, and relationship to other works. The University of Toronto's Writing Center provides a comprehensive list of questions you can use to analyze your sources.

Step 4: Categorize your resources

Divide the available resources that pertain to your research into categories reflecting their roles in addressing your research question. Possible ways to categorize resources include organization by:

• methodology
• theoretical/philosophical approach

Regardless of the division, each category should be accompanied by thorough discussions and explanations of strengths and weaknesses, value to the overall survey, and comparisons with similar sources. You may have enough resources when:

• You've used multiple databases and other resources (web portals, repositories, etc.) to get a variety of perspectives on the research topic.
• The same citations are showing up in a variety of databases.

Additional resources

Undergraduate student resources.

• Literature Review Handout (University of North Carolina at Chapel Hill)
• Learn how to write a review of literature (University of Wisconsin-Madison)

Graduate student and faculty resources

• Information Research Strategies (University of Arizona)
• Literature Reviews: An Overview for Graduate Students (NC State University)
• Oliver, P. (2012). Succeeding with Your Literature Review: A Handbook for Students [ebook]
• Machi, L. A. & McEvoy, B. T. (2016). The Literature Review: Six Steps to Success [ebook]
• Graustein, J. S. (2012). How to Write an Exceptional Thesis or Dissertation: A Step-by-Step Guide from Proposal to Successful Defense [ebook]
• Thomas, R. M. & Brubaker, D. L. (2008). Theses and Dissertations: A Guide to Planning, Research, and Writing

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How to write a literature review

What is a literature review.

The literature review is a written overview of major writings and other sources on a selected topic. Sources covered in the review may include scholarly journal articles, books, government reports, Web sites, etc. The literature review provides a description, summary and evaluation of each source. It is usually presented as a distinct section of a graduate thesis or dissertation.

Purpose of the literature review

The purpose of the literature review is to provide a critical written account of the current state of research on a selected topic:

• Identifies areas of prior scholarship
• Places each source in the context of its contribution to the understanding of the specific issue, area of research, or theory under review.
• Describes the relationship of each source to the others that you have selected
• Identifies new ways to interpret, and shed light on any gaps in, previous research
• Points the way forward for further research.

Components of the literature review

The literature review should include the following:

• Objective of the literature review
• Overview of the subject under consideration.
• particular position, those opposed, and those offering completely different arguments.
• Discussion of both the distinctiveness of each source and its similarities with the others.

Steps in the literature review process

Preparation of a literature review may be divided into four steps:

• Define your subject and the scope of the review.
• Search the library catalogue, subject specific databases and other search tools to find sources that are relevant to your topic.
• Read and evaluate the sources and to determine their suitability to the understanding of topic at hand (see the Evaluating sources section).
• Analyse, interpret and discuss the findings and conclusions of the sources you selected.

Evaluating sources

In assessing each source, consideration should be given to:

• What is the author's expertise in this particular field of study (credentials)?
• Are the author's arguments supported by empirical evidence (e.g. quantitative/qualitative studies)?
• Is the author's perspective too biased in one direction or are opposing studies and viewpoints also considered?
• Does the selected source contribute to a more profound understanding of the subject?

Examples of a published literature review

Literature reviews are often published as scholarly articles, books, and reports. Here is an example of a recent literature review published as a scholarly journal article:

Ledesma, M. C., & Calderón, D. (2015). Critical race theory in education: A review of past literature and a look to the future. Qualitative Inquiry, 21(3), 206-222. Link to the article

Additional sources on writing literature reviews

Further information on the literature review process may be found below:

• Booth, A., Papaioannou, D., & Sutton, A. (2012). Systematic approaches to a successful literature review
• Fink, A. (2010). Conducting research literature reviews: From the Internet to paper
• Galvin, J. (2006). Writing literature reviews: A guide for students of the social and behavioral sciences
• Machi, L. A., & McEvoy, B. T. (2012). The literature review: Six steps to success

Adapted with permission and thanks from How to Write a Literature Review originally created by Kenneth Lyons, McHenry Library, University of California, Santa Cruz.

How to write a Literature Review: Home

• Literature review process
• Purpose of a literature review
• Evaluating sources
• Managing sources
• Request a literature search
• Selecting the approach to use
• Quantitative vs qualitative method
• Summary of different research methodologies
• Research design vs research methodology
• Diagram: importance of research
• Attributes of a good research scholar

Useful information

Visit our  Ask a Librarian  page if you want to contact us or if you have a question.

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Requesting and downloading library material

Guidelines for submission of electronic versions of theses and dissertations 

Click here for more information on the UnisaIR.

What is a literature review

A literature review is a  critical evaluation  of what has been published on a topic by accredited scholars and researchers.  In other words literature reviews are secondary sources, and as such, do not report any new or original experimental work.  Thus, a literature review is not descriptive but analytical in nature. 

More information ...

It is important, however, that you select your sources carefully as you do not have to include everything that you have read on a topic. You must concentrate on publications that have influenced the field you are writing about. Ensure that you use publications that are written by reputable authors.

"A literature review is a piece of  discursive prose , not a list describing or summarizing one piece of literature after another. It's usually a bad sign to see every paragraph beginning with the name of a researcher. Instead, organize the literature review into sections that present themes or identify trends, including relevant theory. You are not trying to list all the material published, but to synthesize and evaluate it according to the guiding concept of your thesis or research question" (Taylor, D. n.d.).

  Source : Taylor D. (n.d.)  T he Literature review: a few tips on conducting it.

Literature review - questions to ask yourself

Useful links.

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• Find e-journals and e-books
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• Last Updated: Apr 30, 2024 1:19 PM
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Literature Reviews

• Types of reviews
• Getting started

Types of reviews and examples

Choosing a review type.

• 1. Define your research question
• 2. Plan your search
• 3. Search the literature
• 4. Organize your results
• 5. Synthesize your findings
• 6. Write the review
• Artificial intelligence (AI) tools
• Thompson Writing Studio This link opens in a new window
• Need to write a systematic review? This link opens in a new window

Contact a Librarian

Ask a Librarian

• Meta-analysis
• Systematized

Definition:

"A term used to describe a conventional overview of the literature, particularly when contrasted with a systematic review (Booth et al., 2012, p. 265).

Characteristics:

• Provides examination of recent or current literature on a wide range of subjects
• Varying levels of completeness / comprehensiveness, non-standardized methodology
• May or may not include comprehensive searching, quality assessment or critical appraisal

Mitchell, L. E., & Zajchowski, C. A. (2022). The history of air quality in Utah: A narrative review.  Sustainability ,  14 (15), 9653.  doi.org/10.3390/su14159653

Booth, A., Papaioannou, D., & Sutton, A. (2012). Systematic approaches to a successful literature review. London: SAGE Publications Ltd.

"An assessment of what is already known about a policy or practice issue...using systematic review methods to search and critically appraise existing research" (Grant & Booth, 2009, p. 100).

• Assessment of what is already known about an issue
• Similar to a systematic review but within a time-constrained setting
• Typically employs methodological shortcuts, increasing risk of introducing bias, includes basic level of quality assessment
• Best suited for issues needing quick decisions and solutions (i.e., policy recommendations)

Learn more about the method:

Khangura, S., Konnyu, K., Cushman, R., Grimshaw, J., & Moher, D. (2012). Evidence summaries: the evolution of a rapid review approach.  Systematic reviews, 1 (1), 1-9.  https://doi.org/10.1186/2046-4053-1-10

Virginia Commonwealth University Libraries. (2021). Rapid Review Protocol .

Quarmby, S., Santos, G., & Mathias, M. (2019). Air quality strategies and technologies: A rapid review of the international evidence.  Sustainability, 11 (10), 2757.  https://doi.org/10.3390/su11102757

Grant, M.J. & Booth, A. (2009). A typology of reviews: an analysis of the 14 review types and associated methodologies.  Health Information & Libraries Journal , 26(2), 91-108. https://www.doi.org/10.1111/j.1471-1842.2009.00848.x

Developed and refined by the Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre), this review "map[s] out and categorize[s] existing literature on a particular topic, identifying gaps in research literature from which to commission further reviews and/or primary research" (Grant & Booth, 2009, p. 97).

Although mapping reviews are sometimes called scoping reviews, the key difference is that mapping reviews focus on a review question, rather than a topic

Mapping reviews are "best used where a clear target for a more focused evidence product has not yet been identified" (Booth, 2016, p. 14)

Mapping review searches are often quick and are intended to provide a broad overview

Mapping reviews can take different approaches in what types of literature is focused on in the search

Cooper I. D. (2016). What is a "mapping study?".  Journal of the Medical Library Association: JMLA ,  104 (1), 76–78. https://doi.org/10.3163/1536-5050.104.1.013

Miake-Lye, I. M., Hempel, S., Shanman, R., & Shekelle, P. G. (2016). What is an evidence map? A systematic review of published evidence maps and their definitions, methods, and products.  Systematic reviews, 5 (1), 1-21.  https://doi.org/10.1186/s13643-016-0204-x

Tainio, M., Andersen, Z. J., Nieuwenhuijsen, M. J., Hu, L., De Nazelle, A., An, R., ... & de Sá, T. H. (2021). Air pollution, physical activity and health: A mapping review of the evidence.  Environment international ,  147 , 105954.  https://doi.org/10.1016/j.envint.2020.105954

Booth, A. (2016). EVIDENT Guidance for Reviewing the Evidence: a compendium of methodological literature and websites . ResearchGate. https://doi.org/10.13140/RG.2.1.1562.9842 . 

Grant, M.J. & Booth, A. (2009). A typology of reviews: an analysis of the 14 review types and associated methodologies.  Health Information & Libraries Journal , 26(2), 91-108.  https://www.doi.org/10.1111/j.1471-1842.2009.00848.x

"A type of review that has as its primary objective the identification of the size and quality of research in a topic area in order to inform subsequent review" (Booth et al., 2012, p. 269).

• Main purpose is to map out and categorize existing literature, identify gaps in literature—great for informing policy-making
• Search comprehensiveness determined by time/scope constraints, could take longer than a systematic review
• No formal quality assessment or critical appraisal

Learn more about the methods :

Arksey, H., & O'Malley, L. (2005) Scoping studies: towards a methodological framework.  International Journal of Social Research Methodology ,  8 (1), 19-32.  https://doi.org/10.1080/1364557032000119616

Levac, D., Colquhoun, H., & O’Brien, K. K. (2010). Scoping studies: Advancing the methodology. Implementation Science: IS, 5, 69. https://doi.org/10.1186/1748-5908-5-69

Example : 

Rahman, A., Sarkar, A., Yadav, O. P., Achari, G., & Slobodnik, J. (2021). Potential human health risks due to environmental exposure to nano-and microplastics and knowledge gaps: A scoping review.  Science of the Total Environment, 757 , 143872.  https://doi.org/10.1016/j.scitotenv.2020.143872

A review that "[compiles] evidence from multiple...reviews into one accessible and usable document" (Grant & Booth, 2009, p. 103). While originally intended to be a compilation of Cochrane reviews, it now generally refers to any kind of evidence synthesis.

• Compiles evidence from multiple reviews into one document
• Often defines a broader question than is typical of a traditional systematic review

Choi, G. J., & Kang, H. (2022). The umbrella review: a useful strategy in the rain of evidence.  The Korean Journal of Pain ,  35 (2), 127–128.  https://doi.org/10.3344/kjp.2022.35.2.127

Aromataris, E., Fernandez, R., Godfrey, C. M., Holly, C., Khalil, H., & Tungpunkom, P. (2015). Summarizing systematic reviews: Methodological development, conduct and reporting of an umbrella review approach. International Journal of Evidence-Based Healthcare , 13(3), 132–140. https://doi.org/10.1097/XEB.0000000000000055

Rojas-Rueda, D., Morales-Zamora, E., Alsufyani, W. A., Herbst, C. H., Al Balawi, S. M., Alsukait, R., & Alomran, M. (2021). Environmental risk factors and health: An umbrella review of meta-analyses.  International Journal of Environmental Research and Public Dealth ,  18 (2), 704.  https://doi.org/10.3390/ijerph18020704

A meta-analysis is a "technique that statistically combines the results of quantitative studies to provide a more precise effect of the result" (Grant & Booth, 2009, p. 98).

• Statistical technique for combining results of quantitative studies to provide more precise effect of results
• Aims for exhaustive, comprehensive searching
• Quality assessment may determine inclusion/exclusion criteria
• May be conducted independently or as part of a systematic review

Berman, N. G., & Parker, R. A. (2002). Meta-analysis: Neither quick nor easy. BMC Medical Research Methodology , 2(1), 10. https://doi.org/10.1186/1471-2288-2-10

Hites R. A. (2004). Polybrominated diphenyl ethers in the environment and in people: a meta-analysis of concentrations.  Environmental Science & Technology ,  38 (4), 945–956.  https://doi.org/10.1021/es035082g

A systematic review "seeks to systematically search for, appraise, and [synthesize] research evidence, often adhering to the guidelines on the conduct of a review" provided by discipline-specific organizations, such as the Cochrane Collaboration (Grant & Booth, 2009, p. 102).

• Aims to compile and synthesize all known knowledge on a given topic
• Adheres to strict guidelines, protocols, and frameworks
• Time-intensive and often takes months to a year or more to complete
• The most commonly referred to type of evidence synthesis. Sometimes confused as a blanket term for other types of reviews

Gascon, M., Triguero-Mas, M., Martínez, D., Dadvand, P., Forns, J., Plasència, A., & Nieuwenhuijsen, M. J. (2015). Mental health benefits of long-term exposure to residential green and blue spaces: a systematic review.  International Journal of Environmental Research and Public Health ,  12 (4), 4354–4379.  https://doi.org/10.3390/ijerph120404354

"Systematized reviews attempt to include one or more elements of the systematic review process while stopping short of claiming that the resultant output is a systematic review" (Grant & Booth, 2009, p. 102). When a systematic review approach is adapted to produce a more manageable scope, while still retaining the rigor of a systematic review such as risk of bias assessment and the use of a protocol, this is often referred to as a  structured review  (Huelin et al., 2015).

• Typically conducted by postgraduate or graduate students
• Often assigned by instructors to students who don't have the resources to conduct a full systematic review

Salvo, G., Lashewicz, B. M., Doyle-Baker, P. K., & McCormack, G. R. (2018). Neighbourhood built environment influences on physical activity among adults: A systematized review of qualitative evidence.  International Journal of Environmental Research and Public Health ,  15 (5), 897.  https://doi.org/10.3390/ijerph15050897

Huelin, R., Iheanacho, I., Payne, K., & Sandman, K. (2015). What’s in a name? Systematic and non-systematic literature reviews, and why the distinction matters. https://www.evidera.com/resource/whats-in-a-name-systematic-and-non-systematic-literature-reviews-and-why-the-distinction-matters/

• Review Decision Tree - Cornell University For more information, check out Cornell's review methodology decision tree.
• LitR-Ex.com - Eight literature review methodologies Learn more about 8 different review types (incl. Systematic Reviews and Scoping Reviews) with practical tips about strengths and weaknesses of different methods.
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• Last Updated: May 17, 2024 8:42 AM
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Rapid literature review: definition and methodology

Beata smela.

a Assignity, Cracow, Poland

Mondher Toumi

b Public Health Department, Aix-Marseille University, Marseille, France

Karolina Świerk

Clement francois, małgorzata biernikiewicz.

c Studio Slowa, Wroclaw, Poland

Emilie Clay

d Clever-Access, Paris, France

Laurent Boyer

Introduction: A rapid literature review (RLR) is an alternative to systematic literature review (SLR) that can speed up the analysis of newly published data. The objective was to identify and summarize available information regarding different approaches to defining RLR and the methodology applied to the conduct of such reviews.

Methods: The Medline and EMBASE databases, as well as the grey literature, were searched using the set of keywords and their combination related to the targeted and rapid review, as well as design, approach, and methodology. Of the 3,898 records retrieved, 12 articles were included.

Results: Specific definition of RLRs has only been developed in 2021. In terms of methodology, the RLR should be completed within shorter timeframes using simplified procedures in comparison to SLRs, while maintaining a similar level of transparency and minimizing bias. Inherent components of the RLR process should be a clear research question, search protocol, simplified process of study selection, data extraction, and quality assurance.

Conclusions: There is a lack of consensus on the formal definition of the RLR and the best approaches to perform it. The evidence-based supporting methods are evolving, and more work is needed to define the most robust approaches.

Introduction

A systematic literature review (SLR) summarizes the results of all available studies on a specific topic and provides a high level of evidence. Authors of the SLR have to follow an advanced plan that covers defining a priori information regarding the research question, sources they are going to search, inclusion criteria applied to choose studies answering the research question, and information regarding how they are going to summarize findings [ 1 ].

The rigor and transparency of SLRs make them the most reliable form of literature review [ 2 ], providing a comprehensive, objective summary of the evidence for a given topic [ 3 , 4 ]. On the other hand, the SLR process is usually very time-consuming and requires a lot of human resources. Taking into account a high increase of newly published data and a growing need to analyze information in the fastest possible way, rapid literature reviews (RLRs) often replace standard SLRs.

There are several guidelines on the methodology of RLRs [ 5–11 ]; however, only recently, one publication from 2021 attempted to construct a unified definition [ 11 ]. Generally, by RLRs, researchers understand evidence synthesis during which some of the components of the systematic approach are being used to facilitate answering a focused research question; however, scope restrictions and a narrower search strategy help to make the project manageable in a shorter time and to get the key conclusions faster [ 4 ].

The objective of this research was to collect and summarize available information on different approaches to the definition and methodology of RLRs. An RLR has been run to capture publications providing data that fit the project objective.

To find publications reporting information on the methodology of RLRs, searches were run in the Medline and EMBASE databases in November 2022. The following keywords were searched for in titles and abstracts: ‘targeted adj2 review’ OR ‘focused adj2 review’ OR ‘rapid adj2 review’, and ‘methodology’ OR ‘design’ OR ‘scheme’ OR ‘approach’. The grey literature was identified using Google Scholar with keywords including ‘targeted review methodology’ OR ‘focused review methodology’ OR ‘rapid review methodology’. Only publications in English were included, and the date of publication was restricted to year 2016 onward in order to identify the most up-to-date literature. The reference lists of each included article were searched manually to obtain the potentially eligible articles. Titles and abstracts of the retrieved records were first screened to exclude articles that were evidently irrelevant. The full texts of potentially relevant papers were further reviewed to examine their eligibility.

A pre-defined Excel grid was developed to extract the following information related to the methodology of RLR from guidelines:

• Definition,
• Research question and searches,
• Studies selection,
• Data extraction and quality assessment,
• Additional information.

There was no restriction on the study types to be analyzed; any study reporting on the methodology of RLRs could be included: reviews, practice guidelines, commentaries, and expert opinions on RLR relevant to healthcare policymakers or practitioners. The data extraction and evidence summary were conducted by one analyst and further examined by a senior analyst to ensure that relevant information was not omitted. Disagreements were resolved by discussion and consensus.

Studies selection

A total of 3,898 records (3,864 articles from a database search and 34 grey literature from Google Scholar) were retrieved. After removing duplicates, titles and abstracts of 3,813 articles were uploaded and screened. The full texts of 43 articles were analyzed resulting in 12 articles selected for this review, including 7 guidelines [ 5–11 ] on the methodology of RLRs, together with 2 papers summarizing the results of the Delphi consensus on the topic [ 12 , 13 ], and 3 publications analyzing and assessing different approaches to RLRs [ 4 , 14 , 15 ].

Overall, seven guidelines were identified: from the World Health Organization (WHO) [ 5 ], National Collaborating Centre for Methods and Tools (NCCMT) [ 7 ], the UK government [ 8 ], the Oxford Centre for Evidence Based Medicine [ 9 ], the Cochrane group [ 6 , 11 ], and one multi-national review [ 10 ]. Among the papers that did not describe the guidelines, Gordon et al. [ 4 ] proposed 12 tips for conducting a rapid review in the right settings and discussed why these reviews may be more beneficial in some circumstances. The objective of work conducted by Tricco et al. [ 13 ] and Pandor et al. [ 12 ] was to collect and compare perceptions of rapid reviews from stakeholders, including researchers, policymakers, industry, journal editors, and healthcare providers, and to reach a consensus outlining the domains to consider when deciding on approaches for RLRs. Haby et al. [ 14 ] run a rapid review of systematic reviews and primary studies to find out the best way to conduct an RLR in health policy and practice. In Tricco et al. (2022) [ 15 ], JBI position statement for RLRs is presented.

From all the seven identified guidelines information regarding definitions the authors used for RLRs, approach to the PICOS criteria and search strategy development, studies selection, data extractions, quality assessment, and reporting were extracted.

Cochrane Rapid Reviews Methods Group developed methods guidance based on scoping review of the underlying evidence, primary methods studies conducted, as well as surveys sent to Cochrane representative and discussion among those with expertise [ 11 ]. They analyzed over 300 RLRs or RLR method papers and based on the methodology of those studies, constructed a broad definition RLR, one that meets a minimum set of requirements identified in the thematic analysis: ‘ A rapid review is a form of knowledge synthesis that accelerates the process of conducting a traditional systematic review through streamlining or omitting a variety of methods to produce evidence in a resource-efficient manner .’ This interpretation aligns with more than 50% of RLRs identified in this study. The authors additionally provided several other definitions, depending on specific situations or requirements (e.g., when RLR is produced on stakeholder’s request). It was additionally underlined that RLRs should be driven by the need of timely evidence for decision-making purposes [ 11 ].

Rapid reviews vary in their objective, format, and methods used for evidence synthesis. This is a quite new area, and still no agreement on optimal methods can be found [ 5 ]. All of the definitions are highlighting that RLRs are completed within shorter timeframes than SLRs, and also lack of time is one of the main reasons they are conducted. It has been suggested that most rapid reviews are conducted within 12 weeks; however, some of the resources suggest time between a few weeks to no more than 6 months [ 5 , 6 ]. Some of the definitions are highlighting that RLRs follow the SLR process, but certain phases of the process are simplified or omitted to retrieve information in a time-saving way [ 6 , 7 ]. Different mechanisms are used to enhance the timeliness of reviews. They can be used independently or concurrently: increasing the intensity of work by intensifying the efforts of multiple analysts by parallelization of tasks, using review shortcuts whereby one or more systematic review steps may be reduced, automatizing review steps by using new technologies [ 5 ]. The UK government report [ 8 ] referred to two different RLRs: in the form of quick scoping reviews (QSR) or rapid evidence assessments (REA). While being less resource and time-consuming compared to standard SLRs, QSRs and REAs are designed to be similarly transparent and to minimize bias. QSRs can be applied to rather open-ended questions, e.g., ‘what do we know about something’ but both, QSRs and REAs, provide an understanding of the volume and characteristics of evidence on a specific topic, allowing answering questions by maximizing the use of existing data, and providing a clear picture of the adequacy of existing evidence [ 8 ].

Research questions and searches

The guidelines suggest creating a clear research question and search protocol at the beginning of the project. Additionally, to not duplicate RLRs, the Cochrane Rapid Reviews Methods Group encourages all people working on RLRs to consider registering their search protocol with PROSPERO, the international prospective register of reviews; however, so far they are not formally registered in most cases [ 5 , 6 ]. They also recommend involving key stakeholders (review users) to set and refine the review question, criteria, and outcomes, as well as consulting them through the entire process [ 11 ].

Regarding research questions, it is better to structure them in a neutral way rather than focus on a specific direction for the outcome. By doing so, the researcher is in a better position to identify all the relevant evidence [ 7 ]. Authors can add a second, supportive research question when needed [ 8 ]. It is encouraged to limit the number of interventions, comparators and outcomes, to focus on the ones that are most important for decision-making [ 11 ]. Useful could be also reviewing additional materials, e.g., SLRs on the topic, as well as conducting a quick literature search to better understand the topic before starting with RLRs [ 7 ]. In SLRs researchers usually do not need to care a lot about time spent on creating PICOS, they need to make sure that the scope is broad enough, and they cannot use many restrictions. When working on RLRs, a reviewer may spend more or less time defining each of the components of the study question, and the main step is making sure that PICOS addresses the needs of those who requested the rapid review, and at the same time, it is feasible within the required time frame [ 7 ]. Search protocol should contain an outline of how the following review steps are to be carried out, including selected search keywords and a full strategy, a list of data sources, precise inclusion and exclusion criteria, a strategy for data extraction and critical appraisal, and a plan of how the information will be synthesized [ 8 ].

In terms of searches running, in most cases, an exhaustive process will not be feasible. Researchers should make sure that the search is effective and efficient to produce results in a timely manner. Cochrane Rapid Reviews Methods Group recommends involving an information specialist and conducting peer review of at least one search strategy [ 11 ]. According to the rapid review guidebook by McMaster University [ 7 ], it is important that RLRs, especially those that support policy and program decisions, are being fed by the results of a body of literature, rather than single studies, when possible. It would result in more generalizable findings applied at the level of a population and serve more realistic findings for program decisions [ 7 ]. It is important to document the search strategy, together with a record of the date and any date limits of the search, so that it can easily be run again, modified, or updated. Furthermore, the information on the individual databases included in platform services should always be reported, as this depends on organizations’ subscriptions and must be included for transparency and repeatability [ 7 , 8 ]. Good solution for RLRs is narrowing the scope or searching a limited number of databases and other sources [ 7 ]. Often, the authors use the PubMed/MEDLINE, Cochrane Library, and Embase databases. In most reviews, two or more databases are searched, and common limits are language (usually restricted to English), date, study design, and geographical area. Some RLRs include searching of grey literature; however, contact with authors is rather uncommon [ 5 , 8 ]. According to the flexible framework for restricted systematic review published by the University of Oxford, the search should be run in at least one major scientific database such as PubMed, and one other source, e.g., Google Scholar [ 9 ]. Grey literature and unpublished evidence may be particularly needed and important for intervention questions. It is related to the fact that studies that do not report the effects of interventions are less likely to be published [ 8 ]. If there is any type of evidence that will not be considered by the RLRs, e.g., reviews or theoretical and conceptual studies, it should also be stated in the protocol together with justification [ 8 ]. Additionally, authors of a practical guide published by WHO suggest using a staged search to identify existing SLRs at the beginning, and then focusing on studies with other designs [ 5 ]. If a low number of citations have been retrieved, it is acceptable to expand searches, remove some of the limits, and add additional databases and sources [ 7 ].

Searching for RLRs is an iterative process, and revising the approach is usually needed [ 7 ]. Changes should be confirmed with stakeholders and should be tracked and reflected in the final report [ 5 ].

The next step in the rapid review is the selection of studies consisting of two phases: screening of titles and abstracts, and analysis of full texts. Prior to screening initiation, it is recommended to conduct a pilot exercise using the same 30–50 abstracts and 5–10 full-texts for the entire screening team in order to calibrate and test the review form [ 11 ]. In contrast to SLRs, it can be done by one reviewer with or without verification by a second one. If verification is performed, usually the second reviewer checks only a subset of records and compares them. Cochrane Group, in contrast, recommends a stricter approach: at least 20% of references should be double-screened at titles and abstracts stage, and while the rest of the references may be screened by one reviewer, the excluded items need to be re-examined by second reviewer; similar approach is used in full-text screening [ 11 ]. This helps to ensure that bias was reduced and that the PICOS criteria are applied in a relevant way [ 5 , 8 , 9 , 11 ]. During the analysis of titles and abstracts, there is no need to report reasons for exclusion; however, they should be tracked for all excluded full texts [ 7 ].

Data extraction and quality assessment

According to the WHO guide, the most common method for data extraction in RLRs is extraction done by a single reviewer with or without partial verification. The authors point out that a reasonable approach is to use a second reviewer to check a random sample of at least 10% of the extractions for accuracy. Dual performance is more necessary for the extraction of quantitative results than for descriptive study information. In contrast, Cochrane group recommends that second reviewer should check the correctness and completeness of all data [ 11 ]. When possible, extractions should be limited to key characteristics and outcomes of the study. The same approach to data extraction is also suggested for a quality assessment process within rapid reviews [ 5 , 9 , 11 ]. Authors of the guidebook from McMaster University highlight that data extraction should be done ideally by two reviewers independently and consensus on the discrepancies should always be reached [ 7 ]. The final decision on the approach to this important step of review should depend on the available time and should also reflect the complexity of the research question [ 9 ].

For screening, analysis of full texts, extractions, and quality assessments, researchers can use information technologies to support them by making these review steps more efficient [ 5 ].

Before data reporting, a reviewer should prepare a document with key message headings, executive summary, background related to the topic and status of the current knowledge, project question, synthesis of findings, conclusions, and recommendations. According to the McMaster University guidebook, a report should be structured in a 1:2:20 format, that is, one page for key messages, two pages for an executive summary, and a full report of up to 20 pages [ 7 ]. All the limitations of the RLRs should be analyzed, and conclusions should be drawn with caution [ 5 ]. The quality of the accumulated evidence and the strength of recommendations can be assessed using, e.g., the GRADE system [ 5 ]. When working on references quoting, researchers should remember to use a primary source, not secondary references [ 7 ]. It would be worth considering the support of some software tools to automate reporting steps. Additionally, any standardization of the process and the usage of templates can support report development and enhance the transparency of the review [ 5 ].

Ideally, all the review steps should be completed during RLRs; however, often some steps may need skipping or will not be completed as thoroughly as should because of time constraints. It is always crucial to decide which steps may be skipped, and which are the key ones, depending on the project [ 7 ]. Guidelines suggest that it may be helpful to invite researchers with experience in the operations of SLRs to participate in the rapid review development [ 5 , 9 ]. As some of the steps will be completed by one reviewer only, it is important to provide them with relevant training at the beginning of the process, as well as during the review, to minimize the risk of mistakes [ 5 ].

Additional information

Depending on the policy goal and available resources and deadlines, methodology of the RLRs may be modified. Wilson et al. [ 10 ] provided extensive guidelines for performing RLR within days (e.g., to inform urgent internal policy discussions and/or management decisions), weeks (e.g., to inform public debates), or months (e.g., to inform policy development cycles that have a longer timeline, but that cannot wait for a traditional full systematic review). These approaches vary in terms of data synthesis, types of considered evidence and project management considerations.

In shortest timeframes, focused questions and subquestions should be formulated, typically to conduct a policy analysis; the report should consist of tables along with a brief narrative summary. Evidence from SLRs is often considered, as well as key informant interviews may be conducted to identify additional literature and insights about the topic, while primary studies and other types of evidence are not typically feasible due to time restrictions. The review would be best conducted with 1–2 reviewers sharing the work, enabling rapid iterations of the review. As for RLRs with longer timeline (weeks), these may use a mix of policy, systems and political analysis. Structure of the review would be similar to shorter RLRs – tabular with short narrative summary, as the timeline does not allow for comprehensive synthesis of data. Besides SLRs, primary studies and other evidence may be feasible in this timeframe, if obtained using the targeted searches in the most relevant databases. The review team should be larger, and standardized procedures for reviewing of the results and data extraction should be applied. In contrast to previous timeframe, merit review process may be feasible. For both timeframes, brief consultations with small transdisciplinary team should be conducted at the beginning and in the final stage of the review to discuss important matters.

For RLRs spanning several months, more comprehensive methodology may be adapted in terms of data synthesis and types of evidence. However, authors advise that review may be best conducted with a small review team in order to allow for more in-depth interpretation and iteration.

Studies analyzing methodology

There have been two interesting publications summarizing the results of Delphi consensus on the RLR methodology identified and included in this review [ 12 , 13 ].

Tricco et al. [ 13 ] first conducted an international survey and scoping review to collect information on the possible approaches to the running of rapid reviews, based on which, they employed a modified Delphi method that included inputs from 113 stakeholders to explore the most optimized approach. Among the six most frequent rapid review approaches (not all detailed here) being evaluated, the approach that combines inclusion of published literature only, a search of more than one database and limitations by date and language, study selection by one analyst, data extraction, and quality assessment by one analyst and one verifier, was perceived as the most feasible approach (72%, 81/113 responses) with the potentially lowest risk of bias (12%, 12/103). The approach ranked as the first one when considering timelines assumes updating of the search from a previously published review, no additional limits on search, studies selection and data extraction done by one reviewer, and no quality assessment. Finally, based on the publication, the most comprehensive RLRs can be made by moving on with the following rules: searching more than one database and grey literature and using date restriction, and assigning one reviewer working on screening, data extraction, and risk of bias assessment ( Table 1 ). Pandor et al. [ 12 ] introduced a decision tool for SelecTing Approaches for Rapid Reviews (STARR) that were produced through the Delphi consensus of international experts through an iterative and rigorous process. Participants were asked to assess the importance of predefined items in four domains related to the rapid review process: interaction with commissioners, understanding the evidence base, data extraction and synthesis methods, and reporting of rapid review methods. All items assigned to four domains achieved > 70% of consensus, and in that way, the first consensus-driven tool has been created that supports authors of RLRs in planning and deciding on approaches.

Six most frequent approaches to RLRs (adapted from Tricco et al. [ 13 ]).

Haby et al. [ 14 ] run searches of 11 databases and two websites and developed a comprehensive overview of the methodology of RLRs. With five SLRs and one RCT being finally included, they identified the following approaches used in RLRs to make them faster than full SLRs: limiting the number and scope of questions, searching fewer databases, limited searching of grey literature, restrictions on language and date (e.g., English only, most recent publications), updating the existing SLRs, eliminating or limiting hand searches of reference lists, noniterative search strategies, eliminating consultation with experts, limiting dual study selection, data extraction and quality assessment, minimal data synthesis with short concise conclusions or recommendations. All the SLRs included in this review were consistent in stating that no agreed definition of rapid reviews is available, and there is still no final agreement on the best methodological rules to be followed.

Gordon et al. [ 4 ] explained the advantages of performing a focused review and provided 12 tips for its conduction. They define focused reviews as ‘a form of knowledge synthesis in which the components of the systematic process are applied to facilitate the analysis of a focused research question’. The first tip presented by the authors is related to deciding if a focused review is a right solution for the considered project. RLRs will suit emerging topics, approaches, or assessments where early synthesis can support doctors, policymakers, etc., but also can direct future research. The second, third, and fourth tips highlight the importance of running preliminary searches and considering narrowing the results by using reasonable constraints taking into account the local context, problems, efficiency perspectives, and available time. Further tips include creating a team of experienced reviewers working on the RLRs, thinking about the target journal from the beginning of work on the rapid review, registering the search protocol on the PROSPERO registry, and the need for contacting authors of papers when data available in publications are missing or incongruent. The last three tips are related to the choice of evidence synthesis method, using the visual presentation of data, and considering and describing all the limitations of the focused review.

Finally, a new publication by Tricco et al. from 2022, describing JBI position statement [ 15 ] underlined that for the time being, there is no specific tool for critical appraisal of the RLR’s methodological quality. Instead, reviewers may use available tools to assess the risk of bias or quality of SLRs, like ROBIS, the JBI critical appraisal tools, or the assessment of multiple systematic reviews (AMSTAR).

Inconsistency in the definitions and methodologies of RLR

Although RLR was broadly perceived as an approach to quicken the conduct of conventional SLR, there is a lack of consensus on the formal definition of the RLR, so as to the best approaches to perform it. Only in 2021, a study proposing unified definition was published; however, it is important to note that the most accurate definition was only matching slightly over 50% of papers analysed by the authors, which underlines the lack of homogeneity in the field [ 11 ]. The evidence-based supporting methods are evolving, and more evidence is needed to define the most robust approaches [ 5 ].

Diverse terms are used to describe the RLR, including ‘rapid review’, focused systematic review’, ‘quick scoping reviews’, and ‘rapid evidence assessments’. Although the general principles of conducting RLR are to accelerate the whole process, complexity was seen in the methodologies used for RLRs, as reflected in this study. Also, inconsistencies related to the scope of the questions, search strategies, inclusion criteria, study screening, full-text review, quality assessment, and evidence presentation were implied. All these factors may hamper decision-making about optimal methodologies for conducting rapid reviews, and as a result, the efficiency of RLR might be decreased. Additionally, researchers may tend to report the methodology of their reviews without a sufficient level of detail, making it difficult to appraise the quality and robustness of their work.

Advantages and weaknesses of RLR

Although RLR used simplified approaches for evidence synthesis compared with SLR, the methodologies for RLR should be replicable, rigorous, and transparent to the greatest extent [ 16 ]. When time and resources are limited, RLR could be a practical and efficient tool to provide the summary of evidence that is critical for making rapid clinical or policy-related decisions [ 5 ]. Focusing on specific questions that are of controversy or special interest could be powerful in reaffirming whether the existing recommendation statements are still appropriate [ 17 ].

The weakness of RLR should also be borne in mind, and the trade-off of using RLR should be carefully considered regarding the thoroughness of the search, breadth of a research question, and depth of analysis [ 18 ]. If allowed, SLR is preferred over RLR considering that some relevant studies might be omitted with narrowed search strategies and simplified screening process [ 14 ]. Additionally, omitting the quality assessment of included studies could result in an increased risk of bias, making the comprehensiveness of RLR compromised [ 13 ]. Furthermore, in situations that require high accuracy, for example, where a small relative difference in an intervention has great impacts, for the purpose of drafting clinical guidelines, or making licensing decisions, a comprehensive SLR may remain the priority [ 19 ]. Therefore, clear communications with policymakers are recommended to reach an agreement on whether an RLR is justified and whether the methodologies of RLR are acceptable to address the unanswered questions [ 18 ].

Disclosure statement

No potential conflict of interest was reported by the author(s).

Case report

• Open access
• Published: 19 May 2024

Fistulising skin metastases in Crohn’s disease: a case report and review of the literature

• Tanja Elger 1 ,
• Johanna Loibl 1 ,
• Christa Buechler 1 ,
• Sebastian Haferkamp 3 ,
• Jens Werner 2 ,
• Konstantin Drexler 3 ,
• Ulrich Hohenleutner 3 ,
• Karsten Guelow 1 ,
• Claudia Kunst 1 ,
• Arne Kandulski 1 ,
• Pia Goeggelmann 1 ,
• Martina Mueller 1 &
• Hauke Christian Tews 1  

Journal of Medical Case Reports volume  18 , Article number:  252 ( 2024 ) Cite this article

272 Accesses

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Metrics details

Metastatic Crohn’s disease is a rare disorder characterized by various granulomatous skin lesions that occur independently of gastrointestinal tract involvement. However, currently there is no standardized care or specific treatment. Therapeutic approaches include immunosuppressive agents, such as corticosteroids, azathioprine, and monoclonal antibodies targeting inflammatory cytokines like tumor necrosis factor (TNF).

Case presentation

We present a case of a 29-year-old western European woman with significant blind ending abdominal subcutaneous fistulas and abscesses, who sought evaluation in the dermatology department. Histological examination revealed multiple epithelioid cell granulomas. There was no evidence of infectious or rheumatologic diseases such as sarcoidosis. The tentative diagnosis was metastatic Crohn’s disease, which was not related to an intestinal manifestation of the disease. The patient responded to infliximab but had to discontinue it due to an allergic reaction. Subsequent adalimumab treatment failed to induce clinical remission; thus, therapy was switched to ustekinumab, resulting in a positive response. Written informed consent for publication of their clinical details and clinical images was obtained from the patient.

For our study more than 1600 publications were screened for cases of metastatic Crohn’s disease on PubMed database. 59 case reports with 171 patients were included in the analysis and evaluated for localization, diagnostic and therapeutic approaches, and complications and were summarized in this review.

The successful ustekinumab treatment of a patient with metastatic Crohn's disease underscores the potential of this minimally investigated therapeutic option, highlighting the need for future treatment guidelines given the increasing prevalence of such cases.

Peer Review reports

Metastatic Crohn`s disease is a rare disease that primarily affects patients diagnosed with inflammatory bowel diseases (IBD). In rare cases, cutaneous manifestations precede gastrointestinal involvement. It most commonly occurs in the genital region, but can also affect every other part of the body. The lesions present as plaques, ulcers, fissures or papules [ 1 ] and, in rare cases, as fistulas. They are often asymptomatic but may also cause pain or itching. Despite the misleading wording, metastatic Crohn’s disease is not considered an oncologic entity. Instead, the term “metastatic” refers to the involvement of sites with no physical connection to the GI-tract. Metastatic Crohn’s disease must not be mixed up with extraintestinal manifestations of Crohn´s disease. Whereas extraintestinal manifestations such as pyoderma gangraenosum and erythema nodosum represent distinct immunologic phenomena, metastatic Crohn’s disease exhibits the same histological findings as intestinal Crohn’s disease, but on other organ sites.

Usually, a biopsy from the involved site is required for the diagnosis of metastatic Crohn’s disease. Histological findings show non-caseating, sarcoid-like granulomas, Langerhans giant cells and foreign body giant cells surrounded by inflammatory histiocytes, plasma cells and lymphocytes [ 2 ]. For a confirmed diagnosis of metastatic Crohn’s disease, other causes for granulomatous disorders have to be excluded, especially cutaneous sarcoidosis, tuberculosis, syphilis, mycobacterial infections, actinomycosis, deep fungal infections, lymphogranuloma venereum and granuloma inguinale. Also non-granulomatous skin lesions such as hidradenitis suppurativa, pyoderma gangrenosum, impetigo, erythema nodosum, factitial dermatitis from factitial injection of foreign substances, schistosomiasis, chronic lymphedema resulting from obstruction, erysipelas, chronic cellulitis and foreign body reaction need to be ruled out [ 3 ].

To objectively assess intestinal involvement, endoscopy of the upper and lower GI tract along with an abdominal magnetic resonance imaging (MRI) scan should be performed.

Currently, there is no standardized treatment of metastatic Crohn’s disease and no German or European guideline, especially for cases without GI involvement. Only individual case reports exist regarding the therapeutic use of approved medication for intestinal Crohn’s disease in metastatic conditions, including steroids, anti-TNF antibodies, azathioprine, and antibiotic therapy [ 4 , 5 , 6 , 7 ].

Ustekinumab is a human monoclonal IgG1κ-antibody, which binds specifically to the p40-subunit of interleucin 12 (IL-12) and interleucin 23 (IL-23). The bioactivity of IL-12 and IL-23 is inhibited by ustekinumab by preventing the p40 subunit from binding to IL-12Rß1-receptorprotein on the surface of immune cells. It is assumed that hereby the cytokine pathways of Th1- and Th17-cells are interrupted, which both play an important role in the pathogenesis of Crohn’s disease [ 8 ].

We here report a case of metastatic Crohn’s disease successfully treated with ustekinumab at our university hospital and provide a literature review on the current therapeutic options for metastatic Crohn’s disease.

In 2020, a 29-year-old western European woman presented to the dermatology department of our university hospital with pronounced abdominal blind-ending fistulas. The initial patient contact was documented in 2019 when she sought care at the emergency department with multiple recurrent abscesses of the abdominal skin that first appeared after a tick bite a few weeks prior.

Between January 2019 and July 2020, multiple incisions of recurrent abscesses were performed in combination with antibiotic treatment. However, complete healing was not achieved. Instead, the abscess cavities expanded beneath the skin, subsequently forming a system of connected fistulas (Fig.  1 ), as visualized in MRI enterography (Fig.  2 ).

Large subcutaneous fistula, 2020

MRI enterography of the large subcutaneous abdominal fistula (red circle), April 2021

When the patient presented to the dermatology department in 2020, the fistulas showed active inflammation with secretion and were almost 2 cm in diameter. In addition, a blind ending subcutaneous fistula of the thigh could be detected, which also showed active inflammation and secretion.

Histologic examination revealed a granulomatous infiltrate with histiocytes and multinuclear giant cells, forming granulomas. In addition, lymphocytes, plasma cells, neutrophils, and eosinophils, and a granulomatous perivasculitis were observed (Fig.  3 ). Differential diagnoses of granulomatous diseases such as sarcoidosis, tuberculosis and immunodeficiencies were ruled out, confirming the diagnosis of metastatic Crohn’s disease.

Histologic examination of a fistula biopsy showing granulomas with histiocytes and multinuclear giant cells, July 2020

To investigate intestinal involvement, abdominal MRI, gastroscopy, and colonoscopy were performed. However, these examinations did not reveal any gastrointestinal involvement at this time. Moreover, fecal calprotectin levels were normal. There was no history of inflammatory bowel disease in the patient’s family.

Antibiotic therapy had failed in the past, but the Patient responded well to prednisolone. As maintenance therapy for metastatic Crohn’s disease, the patient initially received infliximab at a dosage of 5 mg/kg. The patient responded well to this therapy, leading to the cessation of fluid secretion by the fistulas. However, an allergic reaction with dyspnea and rash occurred after the 10th dose of infliximab in October 2021, necessitating the discontinuation of treatment.

To evaluate further treatment options, the patient was referred to the department of Gastroenterology in November 2021. Meanwhile, she had developed diarrhea and abdominal pain. MRI revealed a mild ileitis, which, however, could not be validated by colonoscopy.

Therapy was switched to adalimumab in December 2021, to which the patient did not respond. Instead, a new fistula ostium developed.

Despite the lack of evidence for ustekinumab therapy in metastatic Crohn’s disease, and given its established efficacy only for intestinal manifestation, treatment with ustekinumab was initiated in May 2022 with an initial dose of 390 mg intravenous, followed by 90 mg subcutaneous every 8 weeks. This decision was based on the suspicion that the inflammatory processes in the abdominal fistula mirrored those seen in intestinal inflammation. The patient responded well and inflammation decreased within a few weeks. However, fistulas persisted, albeit with reduced secretion.

In June 2022, the blind-ending subcutaneous fistula of the thigh could be successfully treated by surgery after the active inflammation resolved. In April 2023, the abdominal fistula also showed no remaining inflammation, so a complete excision of the abdominal fistulas was performed. At the patients last visit in August 2023, no new fistula or abscesses were detected, but ustekinumab was continued due to the long and complicated clinical history. Written informed consent for publication of their clinical details and clinical images was obtained from the patient.

Review of the current literature

Material and methods.

A data base literature search was performed using the keywords “metastatic” and “Crohn’s” and “disease”. 1,875 reports published from January 2012 to November 2023 were found. The number of papers meeting the search criteria steadily increased, highlighting the clinical relevance of this topic.

So far, 59 case reports including 171 patients and 12 reviews about clinical presentation, diagnostic approach and therapeutic options have been published. However, no statistical analysis of patient characteristics and treatments is available. Therefore, our aim was to objectively assess these items. Moreover, we intended to discuss ustekinumab as a novel but successful therapeutic approach for metastatic Crohn’s disease.

Of the patients with metastatic Crohn’s disease, 74% were female, and 38% of the cases involved individuals under 18 years old. From this cohort, we assessed diagnostic and therapeutic approaches for metastatic Crohn’s disease.

80% of the patients were diagnosed with intestinal Crohn’s disease before or at the time skin lesions appearance, while 10% exhibited gastrointestinal symptoms such as diarrhea or abdominal pain without IBD [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. 7% had isolated extraintestinal manifestations as illustrated in our presented case. Fistulas were described in 13% of all cases [ 4 , 20 , 21 , 22 ], highlighting the rarity of this condition. However, fistula presence or absence was not explicitly mentioned in 58% of all published cases.

At the time of diagnosing metastatic Crohn’s disease, usually skin biopsies are taken and examined. Granulomas were present in 58% of all cases [ 3 , 4 , 5 , 6 , 7 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ], with some studies not commenting on histological findings.

(Fig.  4 ).

Proportion of patients with GI-Involvement, granuloma and fistula ( n  = 171)

The most common localization of metastatic Crohn’s disease was the genital region, including groin, vulva and penis/scrotum (Fig.  5 ). Notably, our case report highlights that metastatic Crohn’s disease can affect almost every part of the body. This is in accordance with other reports describing affected skin at various sites of the body including extremities, trunk or head/face [ 4 , 5 , 16 , 22 , 25 , 30 , 31 , 32 , 36 , 37 , 38 , 41 , 44 , 47 , 48 ].

Localisation of lesions in patients with metastatic Crohn’s disease ( n  = 159)

Less common sites of involvement included intraabdominal abscesses [ 31 , 49 ] and necrotizing endocarditis of the aortic valve with granuloma formation [ 26 ]. Some patients also exhibited lesions on more than one site. They were counted for each site in Fig.  5 . For 12 patients, the site of involvement was not mentioned.

There are no general recommendations for the treatment of metastatic Crohn’s disease, but similar pathophysiological processes are suspected. Hence, established therapeutic regimens for the treatment of intestinal Crohn’s disease are employed. The most common therapeutic approach involves corticosteroid admission (Figure  6 ), often resulting in a lesion reduction. Anti-TNF, especially infliximab, was effective and utilized in 41.6% of cases. Some patients received multiple therapies and were counted accordingly (Fig.  6 ).

Therapeutic approaches for metastatic Crohn’s disease ( n  = 219)

Steroid treatment led to remission or improvement in 30.8% of all described cases (Table  1 ). Excluding unknown cases, steroids induced remission (17.2%) or improvement (55.2%) in 72.4% of patients.

Anti-TNF, especially infliximab, less common also adalimumab and certolizumab, only had an effect (improvement or remission) in 15.6% of the cases. However, excluding unknown cases, remission was induced in 13.3% and improvement in 53.3% of patients (Table  1 ).

Antibiotics, azathioprine and topical tacrolimus also showed positive effects, although azathioprine did not induce remission in any patient. Data regarding surgical interventions, mesalazine, anti-TNF plus azathioprine, MTX/6-MP, ustekinumab, and hyperbaric oxygen therapy are limited and inconclusive based on the literature. Notably and in line with the presented case, two out of three patients achieved remission after treatment with ustekinumab.

Our examination summarizes patient characteristics in metastatic Crohn’s disease and outlines therapeutic options based on the presented case. However, there are some limitations.

We established the diagnosis of metastatic Crohn’s diseases based on clinical and histological findings. Other granulomatous diseases such as sarcoidosis, tuberculosis and immunodeficiencies were ruled out, and histological findings were typical for Crohn’s lesions despite there was no intestinal involvement at the time of diagnosis. However, there is no possibility of completely ruling out any other underlying immunological condition causing similar symptoms. The analyzed case reports mostly also based their diagnosis on histological findings fitting Crohn’s criteria, and often on a known underlying intestinal Crohn’s disease, but in some publications, diagnostic criteria were not discussed in detail.

Our analysis is a summary of published cases and no randomized trial, making it impossible to compare the efficiencies of different therapies. This article outlines various treatment approaches and their success rates according to literature data. However, assessing the patient's condition before and after treatment from literature data can be challenging.

Several patients responded well to antibiotic treatment (see Table  1 ). This was also effective in some patients with GI involvement. Nevertheless, it remains unclear if lesions described as metastatic Crohn’s disease are infectious or a manifestation of Crohn’s disease.

Despite these limitations, treatments for metastatic Crohn`s disease could be evaluated. The most effective treatments, according to the current literature, include steroids and anti-TNF-antibodies. Despite the small number of cases, also azathioprine showed good clinical results. Mesalazine also appeared to positively impact skin lesions in patients with metastatic Crohn’s disease (see Table  1 ).

Conclusively, mesalazine, azathioprine, steroids, and anti-TNF antibodies should be considered as first line therapy for metastatic Crohn´s disease.

In case of treatment failure, there are less common therapeutic options such as ustekinumab, surgical intervention or hyperbaric oxygen therapy, which can be offered to the patient. Although the efficacy cannot be evaluated based on the limited amount of available data, the existing literature as well as our case report suggests a positive effect of ustekinumab in patients with metastatic Crohn’s disease.

Topical tacrolimus can improve the lesions, but there is no case report where topical tacrolimus could induce remission [ 3 , 5 , 9 , 24 , 39 , 57 , 61 ], and can currently not be recommended as a single therapeutic option. It might be useful to support other therapies.

Metastatic Crohn’s disease can affect patients with or without GI involvement. Diagnostics include anamnesis, inspection and biopsies of the involved site as well as endoscopy and MRI.

Currently, with no German, European or American guidelines available, approved therapies for intestinal Crohn’s disease are employed, based on the suspected similar inflammatory pathophysiology in intestinal and extraintestinal sites: Steroids, anti-TNF antibodies, and antibiotics were the primary and most potent agents. Mesalazine and azathioprine as well as less common treatment options such as surgical intervention or hyperbaric oxygen therapy may also be considered in case of treatment failure.

With the increasing number of reported cases of metastatic Crohn’s disease, the need for future guidelines for treating these patients becomes apparent. Our case demonstrates successful ustekinumab treatment for metastatic Crohn’s disease, suggesting a potential new therapeutic option.

Availability of data and materials

Laboratory results, histological findings, imaging and other diagnostic results are available if necessary.

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Elger, T., Loibl, J., Buechler, C. et al. Fistulising skin metastases in Crohn’s disease: a case report and review of the literature. J Med Case Reports 18 , 252 (2024). https://doi.org/10.1186/s13256-024-04569-1

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Severe fever with thrombocytopenia syndrome (SFTS) is a natural focal disease transmitted mainly by tick bites, and the causative agent is SFTS virus (SFTSV). SFTS can rapidly progress to severe disease, with multiple-organ failure (MOF) manifestations such as shock, respiratory failure, disseminated intravascular coagulation (DIC) and death, but cases of SFTS patients with central nervous system (CNS) symptoms onset and marked persistent involuntary shaking of the perioral area and limbs have rarely been reported.

Case presentation

A 69-year-old woman with fever and persistent involuntary shaking of the perioral area and limbs was diagnosed with SFTS with CNS symptom onset after metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF) and peripheral blood identified SFTSV. The patient developed a cytokine storm and MOF during the course of the disease, and after aggressive antiviral, glucocorticoid, and gamma globulin treatments, her clinical symptoms improved, her laboratory indices returned to normal, and she had a good prognosis.

This case gives us great insight that when patients with CNS symptoms similar to those of viral encephalitis combined with thrombocytopenia and leukopenia are encountered in the clinic, it is necessary to consider the possibility of SFTS involving the CNS. Testing for SFTSV nucleic acid in CSF and blood (mNGS or polymerase chain reaction (PCR)) should be carried out, especially in critically ill patients, and treatment should be given accordingly.

Peer Review reports

Severe fever with thrombocytopenia syndrome (SFTS) is a natural focal disease transmitted mainly by tick bites, and the causative agent is a novel Bunyavirus, also known as SFTS virus (SFTSV), belonging to the Phenuiviridae family and the Bandavirus genus, which was first isolated from patient serum by the Chinese Centre for Disease Control and Prevention in 2010 [ 1 ]. The main features of SFTS include fever, thrombocytopenia, leukopenia and gastrointestinal symptoms, and in severe cases, patients may present with multiple‑organ failure (MOF) symptoms such as shock, respiratory failure, disseminated intravascular coagulation (DIC) and death, with a mortality rate of 5–30% in East Asia [ 2 , 3 ]. SFTS may also present with central nervous system (CNS) involvement, which can severely affect the patient’s disease progression and prognosis and is manifested by seizures, psychiatric symptoms, cognitive impairment, and disorders of consciousness [ 4 , 5 ]. However, reports of patients who present with CNS symptoms as the first symptom and with marked persistent involuntary shaking of the perioral area and limbs are rare.

A 69-year-old female patient was admitted to the hospital with fever for 4 days, involuntary shaking around the mouth and limbs for 3 days, and mental abnormalities for 1 day. The patient was admitted to the emergency department of another hospital 4 days before admission because of fever, where her body temperature reached 38.7 °C and she showed poor mental status, less talking, a loss of appetite, but no headache, vomiting, and limb twitching. A routine blood examination showed a white blood cell (WBC) count of 2.28 × 10 9 /L and a platelet count of 165 × 10 9 /L. When given a cooling infusion for symptomatic treatment, her body temperature would temporarily return to normal. Three days before admission, she experienced persistent involuntary trembling around the mouth and lips, as well as trembling of the tongue and extremities. The trembling of the lips, mouth, and both distal upper limbs was especially bothersome and was aggravated by emotional excitement and accompanied by slurred speech. Two days before admission, she had persistent fever, with a body temperature up to 39.6 °C, and the effect of antipyretic drugs was not good. A routine blood examination performed in another hospital showed a WBC count of 1.78 × 10 9 /L and a platelet count of 81 × 10 9 /L, which was significantly decreased compared with the count from the previous examination. One day prior to admission, the patient experienced babbling, restlessness, irritability, and a decline in time and place orientation and calculation power.

The patient had a many-year history of hypertension, diabetes mellitus and hyperlipidaemia; denied a history of working and living in hilly, forested and mountainous areas and travelling; denied a recent history of mosquito bites; and reported a history of close contact with a pet dog in the last month.

Neurological examination after admission showed that the patient had normal arousal but had unclear speech, hyperactivity, irritability. Her time and place orientation and calculation power decreased. The patient was uncooperative in the pharyngeal reflex examination, and involuntary tongue twitching could be seen when the tongue was stretched out. The remaining cranial nerve examination did not show any abnormalities. Perioral and limb involuntary shaking was obvious and persistent, especially in the perioral area and distal part of both upper limbs. Bilateral tendon reflexes were symmetrical, bilateral pathological signs were negative, and meningeal irritation signs were negative.

On admission, viral encephalitis was considered, and intravenous acyclovir antiviral therapy (0.5 g, q8h) was empirically administered. A comprehensive examination revealed that the patient had MOF: (1) Her platelet count further decreased to 63 × 10 9 /L (normal: 100–300 × 10 9 /L), toxic granules were seen in some granulocytes of the peripheral blood smear, and heterogeneous lymphocytes accounted for 21% of the total. (2) She had impaired liver function with elevated liver enzymes (alanine aminotransferase (ALT), 76 IU/L (normal: 5–40 IU/L); aspartate aminotransferase (AST), 188 IU/L (normal: 8–40 IU/L); and gamma-glutamyl transpeptidase (γ-GT), 177 IU/L (normal: 7–50 IU/L)), which was treated with magnesium isoglycyrrhizinate injection and vitamin C for liver protection. (3) She had acute myocardial injury, with an increased heart rate of > 120 beats/minute and markedly elevated myocardial enzyme and B-type natriuretic peptide levels (myoglobin, 299 ng/mL (normal: 25–58 ng/mL); troponin T, 209 ng/L (normal: 0–14 ng/L); and B-type natriuretic peptide, 9,355 pg/mL (normal: 0-125 pg/mL)). Electrocardiograms (ECGs) showed various atypical manifestations, such as short PR intervals; atrial premature, mild ST-segment depression in leads V2V3; and T-wave changes in multiple leads. Cardiac ultrasound showed a normal left ventricular ejection fraction but abnormal segmental motion of the left ventricular wall, biventricular diastolic insufficiency and a small amount of pericardial effusion. Coenzyme Q10 and trimetazidine were given to improve myocardial energy metabolism, and fluid intake and output were closely monitored. (4) The patient had a bacterial infection of the lungs, combined with type I respiratory failure, which were treated with tracheal intubation and mechanical ventilation immediately to assist respiration and antibiotic antimicrobial therapy. The patient did not have prolonged hypoxic injury. (5) She had impaired renal function, with elevated blood urea nitrogen (BUN) (17.33 mmol/L) (normal: 1.7–8.3 mmol/L) and urinary protein. We administered measures to ensure fluid intake and without the use of nephrotoxic drugs. (6) She had impaired pancreatic function, with elevated lipase (56.5 U/L) (normal: 5.6–51.3 U/L); we administered acid-suppressing drugs to inhibit pancreatic secretion and reduce the load and damage to pancreatic tissue. (7) She had abnormal coagulation, with a prolonged prothrombin time (PT) and thrombin time (TT) (15.7 s (normal: 11–15 s) for PT and 22.6 s (normal: 14–21 s) for TT), decreased fibrinogen (1.8 g/L) (normal: 2–4 g/L), and markedly elevated plasma D-dimer (9.01 µg/mL) (normal: 0.01–0.5 µg/mL) and fibrinogen degradation products (FDPs) (28.36 µg/mL) (normal: 0–5 µg/mL). (8) A thrombus had formed in her right peroneal vein and the intermuscular veins of the right and left calves, for which low molecular heparin anticoagulation was given. (9) Her muscle enzyme profiles were variably elevated (creatine kinase (CK), 335 IU/L (normal: 24–195 IU/L); lactate dehydrogenase (LDH), 1347 IU/L (normal: 109–245 IU/L); and alpha-hydroxybutyrate dehydrogenase (α-HBDH), 645 IU/L (normal: 72–182 IU/L)), correlating with inflammatory response-mediated organ damage. (10) The patient experienced a cytokine storm, with significantly increased inflammatory factors (ferritin > 1500 ng/mL (normal: 11-306.8 ng/mL), interleukin (IL)-6 = 49.88 pg/mL (normal: 0–20 pg/mL), IL-8 = 45.99 pg/mL (normal: 0-21.4 pg/mL), and IL-10 = 25.67 pg/mL (normal: 0-5.9 pg/mL), interferon (IFN)-α = 9.76 pg/mL (normal: 0-7.9 pg/mL), and IFN-γ = 18.7 pg/mL (normal: 0-17.3 pg/mL)) in serum (Table  1 ). (11) Finally, the patient showed an electrolyte balance disorder, as evidenced by hypernatremia (154 mmol/L) (normal: 135–145 mmol/L), hyperchloremia (119 mmol/L) (normal: 96–108 mmol/L), hypocalcaemia (1.92 mmol/L) (normal: 2.03–2.67 mmol/L), and hypophosphatemia (0.54 mmol/L) (normal: 0.84–1.65 mmol/L), and treatments included calcium supplementation, phosphorus supplementation, nasal administration of plain water, and a reduction of sodium and chlorine intake.

Lumbar puncture was performed on the second day after admission (Table  2 ). Cerebrospinal fluid (CSF) was colourless and clear, with a pressure of 190 mmH 2 O (normal: 80–180 mmH 2 O) and a WBC count of 3 × 10 6 /L. CSF cytology showed scattered lymphocytes and a few mononuclear cells. The glucose level and protein counts were normal, chloride was slightly elevated (134 mmol/L) (normal: 118–128 mmol/L), immunoglobulins (Ig) were slightly elevated (IgA, 1.03 mg/dL (normal: 0-0.2 mg/dL); IgM, 0.22 mg/dL (normal: 0-0.2 mg/dL); and IgG, 6.68 mg/dL (normal: 0.48–5.86 mg/dL)), and CSF cytokine levels of IL-6 (27.46 pg/mL) (normal: 0–20 pg/mL) and IL-8 (546.93 pg/mL) (normal: 0-21.4 pg/mL) were elevated. CSF was negative for an autoimmune encephalitis antibody profile (NMDAR, CASPR2, AMPAR1, AMPAR2, LGI1, GABABR, DPPX, and IgLON5), neuroparaneoplastic syndrome antibody profile (Hu, Ri, Yo, CV2, Amphiphysin, GAD65, PNMA2, Recoverin, SOX1, Titin, Tr, and Zic4), and CNS demyelination antibody profile (AQP4, GFAP, MBP, and MOG). Metagenomic next-generation sequencing (mNGS) showed that the number of sequences of a novel Bunyavirus of the Bandavirus genus was 59 in the blood and 12 in the CSF. We also excluded acute febrile illnesses by serum and CSF mNGS, such as dengue fever, chikungunya fever, EB virus infection, renal syndrome hemorrhagic fever, and rickettsial disease.

A diagnosis of SFTS that started with symptoms of CNS and encephalitis due to a novel Bunyavirus was considered based on the patient’s clinical presentation and laboratory test results. With immediate effect, acyclovir was adjusted to the broad-spectrum antiviral drug Foscarnet sodium (3 g, q8h); intravenous infusion of dexamethasone (10 mg qd for five days) and intravenous immunoglobulin (IVIG) (0.4 g/kg for five days) were administered to regulate immune function and inhibit the cytokine storm; nifedipine and benidipine hydrochloride were given to reduce the viral-induced calcium inflow to inhibit viral replication, reduce the viral load and increase the platelet count; clonazepam (1 mg, q8h) was given to relieve the patient’s obvious symptoms of involuntary shaking; and adequate symptomatic supportive therapy was given to ensure adequate calorie and protein intake and to maintain water, electrolyte, blood glucose and acid‒base balance.

After 3 days of hospitalization, the patient’s platelet and WBC counts began to rise gradually and returned to normal levels. After 5 days of hospitalization, the patient’s involuntary shaking and psychiatric symptoms were less severe than before, but compliance with activities was still poor, and her cognitive level still had not returned to normal. After 11 days of hospitalization, the lung infection was better than before, and ventilator withdrawal training was started. After 12 days of hospitalization, cranial magnetic resonance imaging (MRI) was performed, which showed slightly high signals in the bilateral anterior temporal lobe, temporal lobe hook gyrus, insular cortex, and bilateral thalamus on fluid attenuated inversion recovery (FLAIR) and diffusion weighted imaging (DWI) (Fig.  1 a-f). After 13 days of hospitalization, a blood sample was negative for novel Bunyavirus nucleic acid. After 16 days of hospitalization, her condition was significantly better than before, she could perform activities as instructed and answer questions correctly, her time and place orientation returned to normal, and her cognitive level was better than before. A electroencephalogram (EEG) was performed, and a full-lead low-wave amplitude state was observed (Fig.  2 ). After 17 days of hospitalization, the ventilator was completely withdrawn, and the tracheal tube was removed. A repeat lumbar puncture 3 weeks after hospitalization showed a pressure of 110 mmH 2 O, a WBC count of 4 × 10 6 /L, a normal protein count, a slightly elevated glucose level (5.19 mmol/L, compared with a glucose of 7.9 mmol/L over the same period), a slightly elevated chlorine level (130 mmol/L), and a return of Ig to normal. The levels of cytokines IL-6 (4.35 pg/mL) and IL-8 (96.17 pg/mL) decreased significantly compared with the previous levels, and the levels of whole-blood cytokines returned to the normal range (IL-6, 12.22 pg/mL; IL-8, 4.62 pg/mL; IL-10, 1.27 pg/mL; IFN-α, 0 pg/mL; and IFN-γ, 1.14 pg/mL) in serum (Table  1 ). No further novel Bunyaviruses were detected by mNGS of the CSF. Meanwhile, MOF gradually recovered, and liver, heart, lung, kidney, pancreas and coagulation function; the muscle enzyme profile; inflammatory factors; and electrolyte levels gradually returned to normal levels.

After antiviral therapy, immunotherapy, life support and symptomatic treatment, the patient’s vital signs were stable 3 weeks after admission, with clear speech and normal higher cortical function to perform tasks correctly on command. The muscle strength of all four limbs was grade 5, muscle tone was normal, bilateral tendon reflexes existed symmetrically, an ataxia test was normal, bilateral pathological signs were negative, and meningeal irritation signs were negative. She was discharged from the hospital in 23 days after admission. The patient was followed up 1 month after she was discharged from the hospital and is now back to her normal living conditions, with normal functioning of the higher cortex, the ability to take care of herself, and the ability to perform all of the activities she regularly engages in.

Cranial MRI of the patient 12 days after admission. Bilateral anterior temporal lobe (a and d) , temporal lobe leptomeningeal gyrus (a and d) , insular cortex (b and e) , and bilateral thalamus (c and f) FLAIR and DWI sequences with slightly high signals

Sixteen-lead resting-state EEG of the patient 16 days after admission. Simultaneous display an EEG record in monopolar and bipolar montages. A low-amplitude state can be seen in all leads. (a) monopolar montage EEG, (b) bipolar montage EEG

Discussion and conclusions

SFTS is an infectious disease caused by SFTSV infection. The epidemic period is mainly in May-August, and SFTSV is mainly transmitted by tick bites to humans. In recent years, interpersonal and human-animal transmission has also been found. An epidemiological survey of SFTS found that 48% of the patients had had close contact with their pets within two weeks of the onset of the disease [ 6 ]. The general population is susceptible, with a higher risk of infection in residents living in areas such as hills, mountains and forests and in people who spend time outdoors. In this case, SFTSV was isolated from blood and CSF. There was no history of tick bites or travel in the wild, but there was a history of close contact with a pet dog within the past month, and we hypothesized that the infected dog might have been the source of SFTSV in this patient.

The pathogenesis of CNS involvement in SFTS patients is unclear. Previous studies have demonstrated that Bunyaviruses have neurological properties of attack, and Park et al. found viral transcripts of novel Bunyaviruses in the brain and spinal cord of an aged model ferret. It is hypothesized that novel Bunyaviruses also involve the CNS, with consequent symptoms [ 7 ]. Possible mechanisms by which SFTSV attacks the CNS include direct invasion, cytokine storms, and impaired immune function. Kaneko et al. [ 8 ] performed an autopsy on a patient with SFTS with rapid CNS involvement, and the pathological findings revealed a massive infiltration of macrophages with high haematoxylin content and inflammatory cells around the microvessels of the cerebral pontine, fibrin deposition in the vessels, and focal degenerative lesions in some neuronal cells. In a variety of brain tissues, positive SFTSV nucleocapsid protein antigens were observed in the immunoblasts infiltrating the vascular lumen, suggesting that SFTSV can invade the CNS directly for disease development. The availability of agents that recognize these antigens also suggest immunoassays are possible and available for serodiagnosis. For example, serum enzyme linked immunosorbent assay or immunofluorescence to determine SFTSV antigens and antibodies have been used for clinical diagnosis [ 9 ]. Several studies [ 10 , 11 , 12 , 13 , 14 , 15 ] have found that the blood levels of several cytokines, including IFN-α, IFN-γ, IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-α, and monocyte chemotactic protein (MCP)-1, are elevated in patients with SFTS, and IL-8 and MCP-1 levels in the CSF are significantly higher than the blood of those who present with CNS symptoms [ 10 ], suggesting that a cytokine storm may increase vascular permeability and prompt SFTSV to cross the blood‒brain barrier (BBB) and invade the CNS. SFTSV was found in the CSF of this patient, suggesting that the virus had invaded the patient’s CNS. The patient’s blood levels of IL-6, IL-8, IL-10, IFN-α, and IFN-γ were markedly elevated compared with normal ranges; IL-6 and IL-8 were elevated in the CSF; and CSF IL-8 levels were significantly higher than the blood levels, which was consistent with the results of a previous study [ 10 , 11 , 12 , 13 , 14 , 15 ], further suggesting that the cytokine storms induced by multiple elevated cytokines may increase BBB vascular permeability and contribute to the SFTSV invasion of the CNS. In patients with SFTS complicated by neurological involvement, protein and glucose levels in the CSF are normal and that an increase in leukocytes in the CSF may be uncommon. However, in the case of a high suspicion both on a clinical and epidemiological level in countries where the infection exists, in these patients the search for MCP-1 and IL-8 in the CSF and serum is indicated and CSF viral RNA detection are recommended.

According to the course of infection, SFTS can be divided into four periods: the incubation period, the febrile period, the MOF period, and the recovery period [ 1 , 2 , 3 , 16 ]. Patients with SFTS can present with neurological symptoms, which usually appear approximately 5 days after the onset of the disease (Table  3 ) and are often regarded as a complication of SFTS, which has been referred to as SFTS-associated encephalopathy/encephalitis (SFTSAE) [ 10 ]. SFTSAE mainly manifests as headache, seizures, mental abnormality, irritability, limb convulsions, cognitive impairment, and impaired consciousness, with an incidence of approximately 19.1-57.02% [ 4 , 5 , 11 , 17 ]. Most patients with SFTSAE develop impaired consciousness, such as coma, before their condition is taken seriously, which leads to a poor prognosis for the patients [ 4 , 18 ]. Most clinicians rely on the clinical manifestations to make the clinical diagnosis. SFTSV has rarely been isolated from CSF. We screened studies and case reports of SFTS with CNS involvement and found no reports of disease onset with CNS symptoms such as marked persistent involuntary shaking of the perioral area and extremities. In this case, the patient first presented with fever, followed by persistent involuntary tremors of the perioral area and limbs and mental behavioural abnormalities such as rambling, irritability and agitation; furthermore, the whole-genome sequence of SFTSV was found by mNGS of blood and CSF. The case reported here is a case of SFTS with CNS symptoms onset, accompanied by perioral and extremity persistent involuntary shaking, which has not been previously reported in the literature. It has been reported in the literature that SFTS patients can have tremors of limbs and muscles [ 8 , 17 , 19 ], but most of them occurred in the middle and late stages of the disease, and the tremor amplitude was small. In this case, the patient had large-amplitude involuntary shaking of the limbs that was persistent and intensified during agitation, which immediately attracted the clinician’s attention. An additional movie file shows this in more detail [see Additional file 1 ]. However, the specific underlying mechanism is not clear, and a description of similar symptoms of viral encephalitis and an analysis of the underlying mechanism have not been found before; therefore, further studies are needed. The course of the disease in this patient was consistent with the general pattern, with the clinical experience of the febrile period, the MOF period, and the recovery period. The febrile period lasted approximately 4 days, followed by MOF involving the liver, heart, lungs, kidneys, and pancreas, and then the recovery period began approximately 2 weeks after the disease onset, with clinical symptoms gradually returning to normal.

There are fewer reports on neurological-related ancillary investigations (CSF, cranial imaging, and EEG) in SFTS patients with CNS involvement, and we analyse this because SFTS patients rarely start with CNS symptoms and go directly to the neurology department and because such patients are generally more severely ill, making it difficult for them to cooperate in completing the relevant investigations. In a few previous studies, lumbar puncture CSF tests in SFTS patients with CNS symptoms were mostly normal, with few abnormal changes in leukocyte counts, sugars and proteins [ 10 , 20 ]. Park et al. [ 10 ] analysed head imaging and EEG in a series of SFTS patients presenting with CNS symptoms, and no new focal lesions were seen on imaging in any of the brain parenchyma, suggesting that the imaging was not specific and that the EEG in the majority of the patients showed a slow-wave background rhythm (δ-θ), a common feature of encephalitis/encephalopathy. In this patient, two lumbar punctures were performed successively, and no CSF leukocyte abnormalities were observed in any of them either; it was presumed that SFTSV infection was less likely to involve the meninges. We performed cranial MRI and EEG on the patient 12 and 16 days after admission, respectively, and slightly high signals were observed in the bilateral anterior temporal lobes, temporal lobe hook gyrus, insular cortex, and bilateral thalamus in the FLAIR and DWI sequences of cranial MRI, all of which were consistent with the general imaging manifestations of viral encephalitis and were presumed to be related to viral invasion. In addition, we should consider the similarities and differences between the above MRI changes and cortical laminar necrosis associated with hypoxia or hypotension. We found that both had MRI high signals distributed along the cortex. However, this patient’s cranial MRI showed cortical high signals only in FLAIR and DWI sequences, and no abnormal signal was found in T1WI, which was the most obvious difference from cortical laminar necrosis. Furthermore, the patient did not show hypotension or significant hypoxic injury, so the changes on cranial MRI were more likely to be inflammatory changes of viral encephalitis and less relevant to cortical laminar necrosis. The background rhythm of the EEG was an α rhythm, and the whole leads were in low amplitude, which was different from previous studies [ 10 ]. It was presumed that the patient’s brain inflammation had tended to recover at that time, but the suppression of cortical function was remained.

There are no specific drugs for the treatment of CNS symptoms in SFTS, and symptomatic supportive treatment is the mainstay. In vitro and ex vivo studies have found that nifedipine or benidipine hydrochloride can inhibit SFTSV replication, reduce viral load, increase platelet counts, and reduce morbidity and mortality, as confirmed in a retrospective clinical study [ 21 , 22 ]. Glucocorticoids can inhibit the cytokine storms caused by the overproduction of cytokines and reduce patient mortality [ 12 , 13 , 23 ], and a Japanese report documented that three SFTS patients with impaired consciousness recovered without any neurological sequelae after short-term glucocorticoid treatment. However, the authors also suggested that the dosage should be minimized and the duration of administration should be shortened to inhibit cytokine storms and provide systemic benefit, rather than high doses or prolonged use, to avoid side effects [ 24 ]. Gamma globulin, which triggers complement activation and viral neutralization and influences the differentiation process of Schwann cells to increase their regenerative potential [ 25 ], has been used to treat other virus-induced encephalitides and can be used for the treatment of CNS symptoms in SFTS. Two successful cases of combined glucocorticoid and IVIG therapy were reported in Korea [ 26 ]. Two case reports documented that plasma exchange therapy reduced cytokine levels but not viral load, presumably making plasma exchange more effective at an early stage [ 27 , 28 ]. However, these are case reports, and the findings should be confirmed by large-scale randomized controlled studies. In this case, the patient was given the broad-spectrum antiviral drug foscarnet sodium, intravenous infusion of dexamethasone and IVIG to regulate the immune function of the body and inhibit the inflammatory storm, nifedipine and benidipine hydrochloride to inhibit viral replication and reduce the viral load, and other symptomatic treatments. The patient’s clinical manifestations and laboratory indicators gradually improved.

The prognosis of patients with SFTS is related to numerous factors, and studies have shown that advanced age; significant elevations in ALT, AST, CK, CK-MB, LDH, γ-GT, and BUN; low platelet count; persistent lowering of blood calcium; and the presence of CNS symptoms are all important influences that can lead to a poor prognosis [ 29 , 30 , 31 , 32 , 33 , 34 ]. Most of these are commonly used to monitor cardiac, hepatic and renal function, and significant abnormalities in their results indicate more severe organ damage and dysfunction. In addition, there is a statistically significant difference in serum viral copy number between deceased and non-dead patients. The mean viral copy number was higher in deceased patients than in surviving patients, and patients with higher copy numbers had higher mortality rates [ 35 , 36 ]. It was shown that the serum viral load detected by polymerase chain reaction (PCR) on admission was higher in SFTSAE patients than in non-encephalitis patients [ 11 ]. The above suggests a relationship between patient serum number of SFTSV RNA copies and encephalitis CNS symptoms and mortality in SFTS patients. CNS symptoms are often considered to be associated with fatal outcomes in patients with SFTS [ 33 ], and early diagnosis and treatment of neurological symptoms can help reduce mortality. Advanced age; long intervals between onset and admission; comorbid diabetes mellitus or subcutaneous haemorrhage; pulmonary rales; low platelet count; elevated neutrophil percentages and LDH, CK, and C-reactive protein (CRP) levels; and decreased chloride concentrations are significantly associated with the development of CNS symptoms and should be taken into consideration in clinical practice [ 11 , 17 ]. We believe that changes in platelet count and CK-MB should be monitored in patients with SFTSAE. As shown in previous, decreased platelet counts and high CK-MB levels are risk factors for poor prognosis in patients with SFTS. The presence of encephalitis is evidence of a more critical condition. Monitoring changes in platelet counts may provide an initial indication of the direction of the patient’s regression. It has been found that in cardiac enzyme profiles, patients presenting with CNS symptoms have elevated CK levels earlier than LDH and AST levels, and elevated liver enzyme levels later than cardiac enzymes [ 17 ]. Therefore, early monitoring of CK-MB levels may have a predictive effect on the development of CNS symptoms in patients. Although the mortality rate of SFTS patients presenting with CNS symptoms is significantly higher [ 11 ], several studies have found [ 11 , 37 , 38 ] that the long-term prognosis of surviving patients is good, with no obvious sequelae after active treatment. In this case, the patient’s laboratory indicators were consistent with the factors leading to a poor prognosis, and the CNS symptoms were prominent, suggesting that the condition was critical, but with timely administration of treatment, the patient’s condition eventually returned to normal.

In summary, we report a case of SFTS in a patient who started with CNS symptoms accompanied by marked persistent involuntary perioral and extremity shaking, and the whole-genome sequence of SFTSV was found by mNGS of both serum and CSF (It is important to note that hospitals where mNGS analysis is unavailable should use real-time fluorescent quantitative PCR to detect SFTS-specific nucleic acids in serum and CSF.). This has given us great insight into the fact that SFTS should be considered a possible cause when patients present with common CNS symptoms of viral encephalitis, such as mental behavioural abnormalities, convulsions, and cognitive deficits, or rare symptoms, such as persistent involuntary shaking of the perioral area and limbs in the rare case of this patient, combined with thrombocytopenia and leukopenia. Prompt lumbar puncture examination for SFTSV should be performed, and appropriate treatment should be given aggressively to reduce mortality.

Data availability

No datasets were generated or analysed during the current study.

Abbreviations

severe fever with thrombocytopenia syndrome

severe fever with thrombocytopenia syndrome virus

multiple-organ failure

disseminated intravascular coagulation

central nervous system

metagenomic next-generation sequencing

cerebrospinal fluid

alanine aminotransferase

aspartate aminotransferase

gamma-glutamyl transpeptidase

electrocardiogram

blood urea nitrogen

prothrombin time

thrombin time

fibrinogen degradation products

creatine kinase

lactate dehydrogenase

alpha-hydroxybutyrate dehydrogenase

interleukin

immunoglobulin

intravenous immunoglobulin

magnetic resonance imaging

fluid attenuated inversion recovery

diffusion weighted imaging

electroencephalogram

tumour necrosis factor

monocyte chemotactic protein

blood-brain barrier

severe fever with thrombocytopenia syndrome -associated encephalopathy/ encephalitis

polymerase chain reaction

C-reactive protein

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This project was supported by National Key Research and Development Program of China (2020YFC2005403), and by China Association for Promotion of Health Science and Technology (JKHY2023001).

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Dawei Shan, Weibi Chen, Gang Liu, Huimin Zhang, Shuting Chai & Yan Zhang

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Dawei Shan and Yan Zhang contributed to the conception and design of the manuscript. Dawei Shan collected the data and drafted the manuscript. Yan Zhang, Weibi Chen, Gang Liu, Huimin Zhang and Shuting Chai reviewed and modified the manuscript. All authors contributed to manuscript revision and read and approved the final submitted version.

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12883_2024_3664_MOESM1_ESM.mp4

Supplementary Material 1. File name: Additional file 1. File format: mp4. Title of data: Video of patient with persistent involuntary shaking of the perioral area and limbs. Description of data: We took this video on day 2 after the patient was admitted to the hospital. The patient develops persistent involuntary shaking of the perioral area and limbs, especially in the perioral area and distal limbs, which is aggravated by agitation and is accompanied by slurred speech.

Supplementary Material 2. CARE Checklist of information to include when writing this case report.

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Shan, D., Chen, W., Liu, G. et al. Severe fever with thrombocytopenia syndrome with central nervous system symptom onset: a case report and literature review. BMC Neurol 24 , 158 (2024). https://doi.org/10.1186/s12883-024-03664-6

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Received : 30 November 2023

Accepted : 02 May 2024

Published : 10 May 2024

DOI : https://doi.org/10.1186/s12883-024-03664-6

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