Emergency Department Diagnosis and Management of Meningitis and Encephalitis

Emergency Department Management of Adults With Infectious Meningitis and Encephalitis (Infectious Disease CME)

Below is a free preview. Log in or subscribe for full access. Or, get a free sample article Emergency Department Management of Abnormal Uterine Bleeding in the Nonpregnant Patient:
Please provide a valid email address.

*NEW* Quick Search this issue!

Table of Contents

About This Issue

Meningitis and encephalitis can have many causes: bacterial, viral, fungal, and iatrogenic, and time is of the essence in treating cases that can be life-threatening. Although it may not be possible to determine the exact cause in the ED, a thorough history and physical examination and targeted testing will ensure that evidence-based management is initiated in a timely way. This issue reviews:

The common and uncommon pathogens causing bacterial, viral, and fungal meningitis and encephalitis.

The accuracy of the “classic triad” of fever, neck stiffness, and altered mental status: is there a way to improve it?

Using combinations of symptoms for improving diagnosis, since Kernig and Brudzinski signs have a sensitivity of just 2%.

The various findings from lumbar puncture/CSF analysis and the evidence to interpret the etiology.

The usefulness of blood and serum studies, based on history and clinical picture.

Determination of the need for CT before lumbar puncture: reviewing international guidelines and criteria to reduce unnecessary testing and delays in treatment.

Antimicrobial therapies for immunocompetent and immunocompromised patients.

Criteria for discharge, medical ward admission, and ICU admission.

Table of Contents
  1. About This Issue
  2. Abstract
  3. Case Presentations
  4. Introduction
  5. Critical Appraisal of the Literature
  6. Etiology and Pathophysiology
    1. Bacterial Infections
    2. Viral Infections
      1. Viral Meningitis
      2. Viral Encephalitis
      3. COVID-19
    3. Fungal Infections
  7. Differential Diagnosis
  8. Prehospital Care
    1. Postexposure Prophylaxis Recommendations for Prehospital Clinicians
  9. Emergency Department Evaluation
    1. History
    2. Physical Examination
  10. Diagnostic Studies
    1. Cerebrospinal Fluid Analysis
      1. Normal Cerebrospinal Fluid Findings
      2. Measurement of Opening Pressure
      3. Cerebrospinal Fluid Cell Counts
      4. Cerebrospinal Fluid Protein Level
      5. Cerebrospinal Fluid to Serum Glucose Ratio
      6. Cerebrospinal Fluid Gram Stain
      7. Cerebrospinal Fluid Culture
      8. Cerebrospinal Fluid Lactate Concentration
      9. Cerebrospinal Fluid Nucleic Acid Amplification Tests
    2. Blood Tests
      1. Complete Blood Cell Count
      2. Liver Enzymes and Disseminated Intravascular Coagulation Panel
      3. C-Reactive Protein
      4. Serum Procalcitonin
      5. Blood Cultures
      6. Serum Polymerase Chain Reaction Testing
      7. Blood Lactate Testing
      8. Serum Cryptococcal Antigen Testing
    3. Imaging Studies
      1. Computed Tomography
        • Performing Computed Tomography Prior to Lumbar Puncture
      2. Magnetic Resonance Imaging
  11. Treatment
    1. Immunocompetent Individuals With Bacterial Meningitis
    2. Immunocompromised Individuals With Bacterial Meningitis
    3. Patients With Suspected Cryptococcal Meningitis
    4. Patients With Viral Infections
    5. Corticosteroids
  12. Special Populations
    1. Patients With Autoimmune Encephalitis
    2. Individuals Without Childhood Immunizations
    3. Healthcare-Associated Infections
  13. Controversies and Cutting-Edge
    1. Other Adjunctive Therapies
    2. Role of Newer Diagnostic Modalities
  14. Disposition
    1. Can Some Patients be Discharged Safely?
  15. Summary
  16. Time- and Cost-Effective Strategies
  17. Risk Management Pitfalls for Meningitis and Encephalitis in the Emergency Department
  18. Case Conclusions
  19. Clinical Pathway for Emergency Department Management of Meningitis and Encephalitis
  20. Tables and Figures
  21. References


Infectious meningitis and encephalitis are often life-threatening illnesses, though prompt workup and targeted treatment can greatly reduce morbidity and mortality. Although presentation of central nervous system infection can sometimes be subtle, this issue focuses on evidence-based strategies for identifying combinations of signs and symptoms to narrow the diagnosis. Identifying meningitis versus encephalitis; bacterial versus viral, fungal, or iatrogenic causes; and providing prompt empiric antimicrobials and appropriate diagnostic testing are key to management. Cerebrospinal fluid testing findings are outlined to help determine a potential cause for symptoms, along with blood and serum testing options. International society guidelines and evidence regarding the need for computed tomography prior to lumbar puncture are presented, which can help reduce unnecessary imaging. Disposition criteria are expanded to help determine whether a patient can go home, or the level of hospital care that will be required for those admitted.

Case Presentations

A 24-year-old woman with a history of migraine presents to the ED with a “splitting” headache…
  • The patient says this headache is more severe than any migraine she has had before.
  • She is noted to have a temperature of 38.3°C, a heart rate of 115 beats/min, and a blood pressure of 105/70 mm Hg.
  • You wonder whether this episode is simply another migraine or something else entirely…
A 62-year-old man with a history of heart transplant presents by EMS as a possible code stroke, with facial droop and partial hemiparesis….
  • On arrival, the patient is noted to be febrile to 38.8°C with a heart rate of 112 beats/min and blood pressure of 131/64 mm Hg.
  • His wife informs you by telephone that he has been developing the symptoms over several days and has also been prone to bizarre fits of laughter and angry outbursts.
  • You wonder whether the patient’s change in behavior is related to the fever, and if so, why?…
A 36-year-old man with a history of IV heroin use and HIV presents to your ED with 2 weeks of worsening headache, neck stiffness, and malaise. Your institution’s sepsis alert is triggered…
  • He admits to poor adherence to his antiretroviral medications for “a long time.”
  • His temperature is 38.5°C; his heart rate, 121 beats/min; and his blood pressure, 95/48 mm Hg.
  • Manipulation of his neck elicits guarding.
  • You order broad-spectrum antibiotics according to a sepsis order set, but you wonder whether these antimicrobials are sufficient to cover for potential causative agents…

How would you manage these patients? Subscribe for evidence-based best practices and to discover the outcomes.

Clinical Pathway for Emergency Department Management of Meningitis and Encephalitis

Clinical Pathway for Emergency Department Management of Meningitis and Encephalitis

Subscribe to access the complete flowchart to guide your clinical decision making.

Tables and Figures

Table 3. Differential Diagnoses, by Symptom, for Meningitis and Encephalitis

Table 1. Common and Notable Causes of Acute Bacterial Meningitis
Table 2. Viral Causes of Encephalitis and Meningitis
Table 4. Postexposure Prophylaxis Regimens for Exposure to Bacterial Pathogens
Table 5. Comparison of Society Guideline Recommendations on Indications for Computed Tomography Before Lumbar Puncture

Subscribe for full access to all Tables and Figures.

Key References

Following are the most informative references cited in this paper, as determined by the authors.

1. * van de Beek D, Cabellos C, Dzupova O, et al. ESCMID guideline: diagnosis and treatment of acute bacterial meningitis. Clin Microbiol Infect. 2016;22:S37-S62. (Practice guideline) DOI: 10.1016/j.cmi.2016.01.007

12. * Wright WF, Pinto CN, Palisoc K, et al. Viral (aseptic) meningitis: a review. J Neurol Sci. 2019;398:176-183. (Review) DOI: 10.1016/j.jns.2019.01.050

17. * Venkatesan A, Tunkel AR, Bloch KC, et al. Case definitions, diagnostic algorithms, and priorities in encephalitis: consensus statement of the International Encephalitis Consortium. Clin Infect Dis. 2013;57(8):1114-1128. (Practice guideline) DOI: 10.1093/cid/cit458

22. * Attia J, Hatala R, Cook DJ, et al. The rational clinical examination. Does this adult patient have acute meningitis? JAMA. 1999;282(2):175-181. (Systematic review; 10 studies) DOI: 10.1001/jama.282.2.175

25. * Julián-Jiménez A, Morales-Casado MI. Usefulness of blood and cerebrospinal fluid laboratory testing to predict bacterial meningitis in the emergency department. Neurologica (Engl Ed). 2019;34(2):105-113. (Review) DOI: 10.1016/j.nrl.2016.05.009

27. * McGill F, Heyderman RS, Michael BD, et al. The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults. J Infect. 2016;72(4):405-438. (Practice guideline) DOI: 10.1016/j.jinf.2016.01.007

39. * Costerus JM, Brouwer MC, Bijlsma MW, et al. Community-acquired bacterial meningitis. Curr Opin Infect Dis. 2017;30(1):135-141. (Review) DOI: 10.1097/QCO.0000000000000335

74. * Brouwer MC, McIntyre P, Prasad K, et al. Corticosteroids for acute bacterial meningitis. Cochrane Database Syst Rev. 2015(9):CD004405. (Cochrane review, meta-analysis; 25 studies, 4121 patients) DOI: 10.1002/14651858.CD004405.pub5

Subscribe to get the full list of 85 references and see how the authors distilled all of the evidence into a concise, clinically relevant, practical resource.

Keywords: meningitis, encephalitis, bacterial, viral, aseptic, fungal, CNS, neck, herpes, HSV, varicella, Kernig, Brudzinski, CSF, fluid, lactate, CT, lumbar puncture, corticosteroids

Publication Information

Andrew N. Hogan, MD; C. Reece Brockman II, MD, FACEP; Amanda Santa Maria, MD

Peer Reviewed By

Corlin Jewell, MD; Benjamin Schnapp, MD, MEd

Publication Date

April 1, 2022

CME Expiration Date

April 1, 2025    CME Information

CME Credits

4 AMA PRA Category 1 Credits™, 4 ACEP Category I Credits, 4 AAFP Prescribed Credits, 4 AOA Category 2-A or 2-B Credits.
Specialty CME Credits: Included as part of the 4 credits, this CME activity is eligible for 4 Infectious Disease CME credits

Pub Med ID: 35315604

Get Permission

Content you might be interested in
Already purchased this course?
Log in to read.
Purchase a subscription

Price: $449/year

140+ Credits!

Purchase Issue & CME Test

Price: $59

+4 Credits!

Money-back Guarantee
Get A Sample Issue Of Emergency Medicine Practice
Enter your email to get your copy today! Plus receive updates on EB Medicine every month.
Please provide a valid email address.