Treatment of Suspected Viral Meningitis with HSV Features
Critical Diagnostic Distinction
- The combination of lymphocytic pleocytosis, mildly elevated protein, and normal or reduced glucose in cerebrospinal fluid (CSF) suggests HSV-2 meningitis, which characteristically presents with these features 1, 2
- Elevated protein with lymphocytic predominance is consistent with viral meningitis, particularly HSV 1
Treatment Algorithm
- The Centers for Disease Control and Prevention (CDC) recommends intravenous acyclovir for HSV-2 meningitis, despite acknowledging that optimal therapies have not been studied 1, 2
- The British Infection Association states there is no evidence supporting acyclovir or valacyclovir for HSV meningitis and recommends supportive care only 5
- For patients over 12 years of age, the recommended dosing of intravenous acyclovir is 10 mg/kg every 8 hours 4
- For children 3 months-12 years, the recommended dosing of intravenous acyclovir is 500 mg/m² every 8 hours 4
Duration of Therapy
- For HSV meningitis, acyclovir 10 mg/kg IV every 8 hours is recommended until resolution of fever and headache, followed by valacyclovir 1g three times daily to complete a 14-day course 1, 2
- For HSV encephalitis, 14-21 days of IV acyclovir is recommended 1, 2, 4
Critical Pitfalls and Caveats
- The risk-benefit ratio favors treatment with acyclovir, as HSV meningitis can progress to encephalitis with high mortality if left untreated 4
- Acyclovir is relatively safe, with the main risk being reversible nephropathy, which can be prevented with adequate hydration 4
- CSF PCR remains positive for 7-10 days even after starting acyclovir, so diagnostic yield is preserved 4
Monitoring Requirements
- Renal function should be monitored closely during IV acyclovir therapy 4
- Adequate hydration should be maintained to prevent crystalluria and obstructive nephropathy 4
- Patients should be reassessed for encephalitis features, which would mandate a full 14-21 day IV course 1, 4