Diagnosis:
Clinical features plus confirmation by CSF analysis & isolation of the virus or PCR or antibody tests
Findings on Investigations:
CSF analysis:
- Early LP may show:
- Increased neutrophils,
- Glucose normal
- Later:
- White cell counts: moderately high,
- <1000/mL (usually 25-500/microL)
- Lymphocytes or monocytes
- RCC: raised in HSV encephalitis
- Glucose normal
- Protein:
- Usually normal
- Or slightly increased 0.2-0.8 g/L (20-80 mg/dL)
- Normal or mildly elevated opening pressure 100-350 mmH2O
- Notes: Recurrent viral meningitis a.k.a. Mollaret meningitis: lymphocytic tap, Mollaret cells= atypical monocytes with bilobed nuclei & amorphous cytoplasm
Confirmatory viral studies:
- PCR: for HSV, enterovirus
- Enterovirus (PCR), coxasckie, echovirus
- HSV2 & 1 (PCR), VZV, EBV, CMV, HHV6
- Arboviruses: St. Louis encephalitis virus, West Nile virus WNV (CSF IgG & IgM), California encephalitis virus, western equine encephalitis virus, eastern equine encephalitis virus, Japanese B virus, Murray Valley virus, coltivirus.
- Zoonosis: Lymphocytic choriomeningitis virus LCMV (paired serology)
- Mumps (paired serology)
- HIV
Treatment:
- Usually self limited
- Treat seizures if they occur
- Consider supportive treatment as needed depending on neurological and systemic status
- If with HSV encephalitis, treat as encephalitis with aciclovir I.V.
- Avoid Aspirin