Summary
Definition
History and exam
Key diagnostic factors
- fever
- rash
- altered mental state
- focal neurologic 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
- postinfection
- 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
- CBC
- 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
- urine culture
- 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 etiology
immunocompromised host: suspected viral etiology
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 nonherpes virus etiology
nonviral etiology
convalescent phase: all etiologies
Contributors
Authors
Payal B. Patel, MD
Clinical Instructor
Department of Neurology
Yale University
New Haven
Connecticut
CT
Disclosures
PBP declares that she has no competing interests.
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
- Case definitions, diagnostic algorithms, and priorities in encephalitis: consensus statement of the International Encephalitis Consortium
More GuidelinesPatient leaflets
Meningitis and septicemia
More Patient leaflets
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