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
- 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
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.
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