Treatment of Herpes Zoster (Shingles) Encephalitis

Immediate Empirical Treatment

The Infectious Diseases Society of America recommends starting intravenous acyclovir immediately at 10 mg/kg every 8 hours for adults and children with normal renal function, continuing for 14-21 days, as early treatment is critical for reducing mortality and neurological sequelae 1, 2, 3
Begin acyclovir within 6 hours of hospital admission for any patient with suspected encephalitis, even before diagnostic confirmation, as delays beyond 48 hours significantly worsen outcomes 1, 4
The standard adult dose is 10 mg/kg intravenously every 8 hours for patients with normal renal function 1, 2, 6
For neonates, use higher-dose acyclovir at 20 mg/kg intravenously every 8 hours for 21 days, which has reduced mortality to 5% 1, 6
Reduce the dose in patients with pre-existing renal impairment to prevent crystalluria and obstructive nephropathy 7

Continue intravenous acyclovir for 14-21 days once VZV encephalitis is confirmed 1, 6, 3
Monitor renal function throughout treatment, as acyclovir-induced nephropathy can affect up to 20% of patients, typically after 4 days of IV therapy 3, 5
Ensure adequate hydration during acyclovir administration to minimize nephrotoxicity risk 5
Consider repeating lumbar puncture at the end of therapy to confirm CSF PCR negativity for VZV, particularly if clinical response is suboptimal 1, 3

CSF PCR can detect varicella zoster virus DNA, though a negative test does not exclude the diagnosis 8, 9
CSF VZV IgM antibodies may be present even when CSF PCR is negative, providing additional diagnostic support 2, 9

Consider adding corticosteroids if VZV vasculopathy (stroke) is present, as there is evidence supporting their use in this specific context 10, 3
The role of routine corticosteroids in VZV encephalitis without vasculopathy remains controversial and should be reserved for specialist supervision 10

Never delay acyclovir beyond 48 hours waiting for diagnostic confirmation, as this is the single most important predictor of poor outcome 1, 5
Do not stop acyclovir based solely on a single negative CSF PCR if clinical suspicion remains high, as PCR sensitivity varies 8, 9
Avoid inadequate hydration during treatment, which significantly increases nephropathy risk 5