Last reviewed: 24 Oct 2020
Last updated: 01 Jul 2020

Summary

Definition

History and exam

Key diagnostic factors

  • headache
  • neck stiffness
  • fever
  • altered mental status
  • vomiting
  • confusion
  • photophobia
  • seizures
  • risk factors

Other diagnostic factors

  • focal neurological signs
  • abnormal eye movement
  • facial palsy
  • balance problems/hearing impairment
  • rash
  • papilloedema
  • Kernig's sign
  • Brudzinski's sign

Risk factors

  • advanced age
  • crowding
  • exposure to pathogens
  • immunocompromising conditions
  • cranial anatomical defects/ventriculoperitoneal shunt 
  • cochlear implants
  • sickle cell disease
  • contiguous infection

Diagnostic investigations

1st investigations to order

  • blood culture
  • serum pneumococcal and meningococcal PCR
  • blood glucose
  • FBC and differential 
  • serum urea, creatinine, and electrolytes
  • venous blood gas
  • LFTs
  • coagulation screen (prothrombin time, INR, activated PTT, fibrinogen, fibrin degradation products)
  • serum HIV
  • serum procalcitonin (PCT)
  • serum CRP if PCT not available
  • cerebrospinal fluid (CSF) protein
  • CSF lactate
  • CSF glucose
  • CSF microscopy, Gram stain, culture, and sensitivities
  • CSF cell count
  • CSF polymerase chain reaction (PCR) for pneumococcus 
Full details

Investigations to consider

  • neuroimaging
  • CSF PCR for tuberculosis
  • CSF PCR for herpes simplex virus (HSV) 1 and 2 and varicella zoster virus
  • CSF, stool, and throat swab PCR for enterovirus
Full details

Treatment algorithm

Contributors

Expert advisersVIEW ALL

Flight Doctor

Greater Sydney Area

Helicopter Emergency Medical Service

New South Wales

Australia 

Disclosures

AA declares that he has no competing interests.

ST4 Emergency Medicine Doctor

Royal London Hospital

Physician Response Unit Clinical Fellow

London

UK

Disclosures

AC declares that she has no competing interests.

BMJ Best Practice would like to gratefully acknowledge the previous team of expert contributors, whose work is retained in parts of the content:

A. Marceline Tutu van Furth, MD, PhD, MBA

Professor in Pediatric Infectious Diseases

Vrije Universiteit Medical Center

Amsterdam

The Netherlands

Disclosures: AMTvF declares that she has no competing interests.

*

Omaima El Tahir, MD

PhD Candidate

Pediatric Infectious Diseases and Immunogenetics

Vrije Universiteit Medical Center

Amsterdam

The Netherlands

Disclosures: OET declares that she has no competing interests.

Peer reviewersVIEW ALL

Acute Hospital Sub Dean (Cornwall)

Honorary Clinical Senior Lecturer

Consultant Emergency Physician

The Knowledge Spa

Royal Cornwall Hospital

Truro

UK 

Disclosures

RT declares that he has no competing interests.

Section Editor, BMJ Best Practice

Disclosures

CP declares that she has no competing interests.

Head of Editorial, BMJ Best Practice

Disclosures

AE declares that she has no competing interests.

Lead Section Editor, BMJ Best Practice

Disclosures

RW declares that she has no competing interests.

Comorbidities Editor, BMJ Best Practice

Disclosures

JC declares that she has no competing interests.

Drug Editor, BMJ Best Practice

Disclosures

IC declares that she has no competing interests.

Drug Editor, BMJ Best Practice

Disclosures

AM declares that he has no competing interests.

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