Management of Encephalitis
The recommended management for encephalitis includes immediate initiation of intravenous acyclovir (10 mg/kg every 8 hours in adults with normal renal function) as soon as encephalitis is suspected, even while awaiting diagnostic test results, as early treatment significantly reduces mortality from 70% to 8-30%. 1
Initial Assessment and Management
- Patients with suspected encephalitis should have urgent neurological specialist assessment and be managed in a setting where clinical neurological review can be obtained within 24 hours of referral 2
- Patients with falling level of consciousness require urgent assessment by Intensive Care Unit staff for airway protection, ventilatory support, management of raised intracranial pressure, and optimization of cerebral perfusion pressure 2
- Metabolic, toxic, autoimmune, and non-CNS sources of sepsis should be considered early in patients presenting with encephalopathy 2
Diagnostic Workup
- Access to neuroimaging (MRI and CT), under general anesthesia if needed, and neurophysiology (EEG) should be available, which may require transfer to a specialist neuroscience unit 2
- Lumbar puncture is crucial with CSF examination for:
- If CSF HSV PCR is not sent on first LP, a repeat CSF PCR should be performed on a second LP 2
Antimicrobial Treatment
Herpes Simplex Virus (HSV) Encephalitis
- Acyclovir should be initiated as soon as possible in all patients with suspected encephalitis 2, 1
- For adults and adolescents (12 years and older): 10 mg/kg IV every 8 hours for 14-21 days 1, 3
- For children (3 months to 12 years): 20 mg/kg IV every 8 hours for 10 days 3
- For neonates (birth to 3 months): 20 mg/kg IV every 8 hours for 10 days 1, 3
- Dose adjustment is required for patients with renal impairment 3
Varicella Zoster Virus (VZV) Encephalitis
- For VZV encephalitis: intravenous acyclovir 10-15 mg/kg three times daily is recommended, with or without a short course of corticosteroids 2
- If there is a vasculitic component, there is a stronger case for using corticosteroids 2
- No specific treatment is needed for VZV cerebellitis as it is usually self-limiting 2
Other Viral Encephalitides
- For cytomegalovirus (CMV) encephalitis: combination therapy with ganciclovir (5 mg/kg IV every 12h) and foscarnet (60 mg/kg IV every 8h or 90 mg/kg IV every 12h) for 3 weeks 1
- For Epstein-Barr virus (EBV) encephalitis: acyclovir has limited benefit and is not recommended; corticosteroids may be beneficial in selected patients 1
Treatment Duration and Monitoring
- Continue intravenous acyclovir for 14-21 days in confirmed HSV encephalitis 1, 4
- Consider repeating lumbar puncture at the end of treatment to confirm CSF is negative for HSV by PCR 1
- Monitor renal function throughout treatment, as acyclovir-induced nephropathy can affect up to 20% of patients, typically after 4 days of IV therapy 1, 5
Special Considerations
- Immunocompromised patients may require longer courses of therapy and closer monitoring 1
- For patients with antibody-mediated encephalitis (presenting with sub-acute onset, orofacial dyskinesia, choreoathetosis, faciobrachial dystonia, intractable seizures, or hyponatremia), different management approaches may be needed 2
Common Pitfalls to Avoid
- Delaying acyclovir treatment beyond 48 hours after hospital admission significantly worsens outcomes 1, 6
- Inadequate hydration during acyclovir treatment increases risk of nephropathy 1
- Relapse can occur after a standard 10-day course of acyclovir; therefore, a 14-21 day course is recommended for HSV encephalitis 4, 7
- Rapid or bolus intravenous injection of acyclovir must be avoided; acyclovir should be infused at a constant rate over 1 hour 3