From the Guidelines
The treatment for Herpes Simplex Encephalitis (HSE) requires immediate administration of intravenous acyclovir at a dose of 10 mg/kg every 8 hours for adults with normal renal function, typically continued for 14-21 days, as recommended by the most recent guidelines 1.
Key Considerations
- Treatment should be initiated as soon as HSE is suspected, even before diagnostic confirmation, as delays significantly increase mortality and neurological sequelae 1.
- For patients with impaired kidney function, the dose should be adjusted accordingly to prevent renal impairment secondary to crystalluria and obstructive nephropathy 1.
- Supportive care is also essential, including management of increased intracranial pressure, seizure control with anticonvulsants if needed, and maintenance of adequate hydration and electrolyte balance.
- Dexamethasone may be considered in cases with significant cerebral edema, though its use remains controversial 1.
Acyclovir Therapy
- Acyclovir works by inhibiting viral DNA synthesis in herpes simplex virus (HSV), the causative agent of HSE 1.
- Early treatment is crucial because the virus rapidly replicates in brain tissue, causing inflammation and necrosis that can lead to permanent neurological damage.
- After the acute treatment phase, some patients may benefit from oral valacyclovir (1000 mg three times daily) as suppressive therapy if they experience recurrent episodes.
Monitoring and Adjustment
- A repeat lumbar puncture should be performed at the end of the treatment period to confirm the CSF is negative for HSV by PCR 1.
- If the CSF is still positive, acyclovir should continue intravenously, with weekly PCR until it is negative 1.
From the FDA Drug Label
Herpes Simplex Encephalitis Acyclovir for Injection is indicated for the treatment of herpes simplex encephalitis Sixty-two patients ages 6 months to 79 years with brain biopsy-proven herpes simplex encephalitis were randomized to receive either acyclovir (10 mg/kg every 8 hours) or vidarabine (15 mg/kg/day) for 10 days The treatment for Herpes Simplex Encephalitis (HSE) is acyclovir (IV), specifically 10 mg/kg every 8 hours for 10 days, as indicated in the clinical trials 2. This is also supported by the indications and usage section of the drug label 2. Acyclovir has been shown to decrease mortality and improve outcomes in patients with HSE.