Summary
Definition
History and exam
Key diagnostic factors
- presence of risk factors
- fever
- rash
- altered mental state
- focal neurological deficit
- meningismus
- parotitis
- lymphadenopathy
- optic neuritis
- acute flaccid paralysis
- movement disorder
Other diagnostic factors
- cough
- gastrointestinal infection
- seizures
- biphasic illness
- autonomic and hypothalamic disturbances
- myocarditis/pericarditis
- jaundice
- arthritis
- retinitis
- parkinsonism
Risk factors
- age <1 or >65 years
- immunodeficiency
- vaccination
- post-infection
- blood/body fluid exposure
- organ transplantation
- animal or insect bites
- location
- season
- occupation
- hunting/trekking in woods
- swimming or diving in warm freshwater or nasal/sinus irrigation
- spelunking (cave-exploring)
- death in animals
- cancer
Diagnostic investigations
1st investigations to order
- FBC
- peripheral blood smear
- serum electrolytes
- liver function tests
- blood cultures
- throat swab
- nasopharyngeal aspirate
- sputum culture
- chest radiography
- CT brain
- MRI brain
- electroencephalogram (EEG)
- cerebrospinal fluid (CSF) analysis
- CSF culture
- CSF serology
- CSF polymerase chain reaction (PCR)
Investigations to consider
- stool enteroviral culture
- IgG and IgM antibodies (blood)
- PCR (blood)
- HIV serology/RNA test
- CSF biomarkers/prion protein assay
- paraneoplastic antibodies (blood and CSF)
- abdominal/pelvic ultrasound
- whole-body CT
- whole-body PET scans
- magnetic resonance spectroscopy
- next-generation sequencing of CSF
- brain biopsy
Treatment algorithm
immunocompetent host: suspected viral aetiology
immunocompromised host: suspected viral aetiology
confirmed herpes simplex virus (HSV) encephalitis
confirmed varicella zoster virus (VZV) encephalitis
confirmed cytomegalovirus (CMV) encephalitis
confirmed Epstein-Barr virus (EBV) encephalitis
confirmed herpes B encephalitis
confirmed human herpes 6 encephalitis
confirmed non-herpes virus aetiology
non-viral aetiology
convalescent phase: all aetiologies
Contributors
Authors
Payal B. Patel, MD
Assistant Professor of Neurology
Department of Neurology
University of Washington
Seattle
WA
Disclosures
PBP has received research funding support from the National Institute of Health and Bayer Pharmaceuticals. PBP has received an honorarium as an author from Medlink Neurology and Continuum Neurology.
Acknowledgements
Dr Payal B. Patel would like to gratefully acknowledge Dr Leo H. Wang, Dr Louise T. Wang, Dr Catalina C. Ionita, Dr Manjunath Markandaya, Dr David Janicke, Dr Robert Schmidt, and Dr Kimiko Domoto-Reilly, previous contributors to this topic.
Disclosures
LHW, LTW, CCI, MM, DJ, RS, and KDR declare that they have no competing interests.
Peer reviewers
Russel Dale, MBChB, MRCPCH, MSc, PhD
Professor of Paediatric Neurology
The University of Sydney
Consultant Neurologist
The Children's Hospital at Westmead
Sydney
Australia
Disclosures
RD declares that he has no competing interests.
Arun Venkatesan, MD, PhD
Associate Professor, Neurology
Director
Johns Hopkins Encephalitis Center
Johns Hopkins Hospital
Baltimore
MD
Disclosures
AV declares that he has no competing interests.
Differentials
- Aseptic meningitis
- Encephalopathy (toxic/metabolic)
- Status epilepticus
More DifferentialsGuidelines
- EAN consensus review on prevention, diagnosis and management of tick‐borne encephalitis
- Consensus guidelines for the investigation and management of encephalitis in adults and children in Australia and New Zealand
More GuidelinesPatient leaflets
Meningitis and septicaemia
More Patient leaflets
Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer