Treatment of Viral Brainstem Encephalitis

Immediate Empiric Antiviral Therapy

The American Academy of Neurology recommends starting intravenous acyclovir 10 mg/kg every 8 hours immediately upon suspicion of viral brainstem encephalitis, as HSV is the most treatable cause and delays beyond 48 hours worsen outcomes 1
Acyclovir must be initiated within 6 hours of admission if CSF/imaging results are not immediately available, or if the patient is severely ill or deteriorating 1, 2
The standard dose is 10 mg/kg IV every 8 hours for adults, continuing for 14-21 days for confirmed HSV encephalitis 1
For children aged 3 months to 12 years, use 10-15 mg/kg three times daily 3
Do not wait for PCR confirmation before starting treatment—CSF remains PCR-positive for several days after acyclovir initiation, so delayed lumbar puncture can still confirm diagnosis 1

For HSV brainstem encephalitis, continue IV acyclovir for 14-21 days 1
Perform repeat lumbar puncture at completion to confirm CSF is HSV PCR-negative 1
If CSF remains positive, continue acyclovir with weekly PCR monitoring until negative 1
For VZV encephalitis, use acyclovir 10-15 mg/kg three times daily for up to 14 days 3, 5
If vasculopathy or stroke-like presentation is present, add corticosteroids (e.g., prednisolone 60-80 mg daily for 3-5 days) due to the inflammatory nature of the lesion 3, 5

Do not use corticosteroids routinely in HSV encephalitis while awaiting results of ongoing randomized controlled trials 3
Exception: VZV vasculopathy with stroke presentation warrants corticosteroids in addition to acyclovir 3, 5

Patients require immediate hospitalization with access to intensive care units 2
Falling level of consciousness demands urgent ICU evaluation for airway protection, ventilatory support, and management of increased intracranial pressure 2
Multidisciplinary involvement includes neurology, infectious disease, virology, neurophysiology, neuroradiology, and intensive care 2
EEG monitoring is essential to identify non-convulsive seizures in confused or comatose patients 5

Lumbar puncture should be performed as soon as possible unless contraindicated by signs of increased intracranial pressure 1, 2
CSF PCR results should be available within 24-48 hours 2
MRI is preferred over CT for neuroimaging 2
Brain biopsy has no role in initial evaluation but should be considered after the first week if no diagnosis is established, especially with focal imaging abnormalities 2

Reduce acyclovir dose in pre-existing renal impairment to prevent crystalluria and obstructive nephropathy, which can affect up to 20% of patients after 4 days of IV therapy 1
Monitor renal function closely throughout treatment 1

Transfer to a specialized neurology service within 24 hours if diagnosis is not rapidly established or patient fails to improve 3, 2
Do not discharge without a definitive or suspected diagnosis 2
All patients require rehabilitation assessment regardless of age 2
Arrange outpatient follow-up with plans for ongoing therapy and rehabilitation 2