From the Guidelines
Viral encephalitis with rash should be treated with empiric acyclovir 10 mg/kg IV every 8 hours for 14-21 days when herpes viruses are suspected or confirmed, as these are treatable causes with high mortality if untreated. The characteristic rash varies by virus: HSV may present with vesicular lesions, VZV with a dermatomal vesicular rash, enteroviruses with maculopapular rashes, and some arboviruses with petechial rashes.
Diagnostic Steps
- Prompt lumbar puncture for CSF analysis
- Brain MRI
- EEG
These diagnostic steps are essential in identifying the cause of viral encephalitis and guiding treatment.
Treatment
- Empiric acyclovir should be started immediately when viral encephalitis is suspected, even before confirmation, as delayed treatment of herpes encephalitis significantly increases mortality and neurological sequelae 1.
- Additional supportive measures include seizure prophylaxis with levetiracetam 500-1000 mg twice daily, careful monitoring of neurological status, and ICU care for severe cases with respiratory compromise or significant altered mental status.
- For non-herpes viral encephalitis, treatment is primarily supportive care including IV fluids, antipyretics, anticonvulsants for seizures, and management of increased intracranial pressure if present.
Important Considerations
- The failure to identify an etiologic agent in many cases of encephalitis may be related to referral bias towards diagnostically challenging cases, as well as lack of access to appropriate specimens and suboptimal specimen handling 1.
- It is essential to distinguish between infectious encephalitis and postinfectious or postimmunization encephalitis or encephalomyelitis, which may be mediated by an immunologic response to an antecedent antigenic stimulus from an infecting microorganism or immunization 1.
In summary, viral encephalitis with rash requires prompt diagnosis and treatment, with empiric acyclovir being the cornerstone of treatment for suspected herpes virus infections. Supportive care and careful monitoring are also crucial in managing these patients.
From the Research
Viral Encephalitis with Rash
- Viral encephalitis is a medical emergency that requires immediate diagnosis and treatment 2
- The diagnosis of viral encephalitis should be based on medical history, examination, and analysis of cerebrospinal fluid for protein and glucose contents, cellular analysis, and identification of the pathogen by polymerase chain reaction (PCR) amplification and serology 2
- Varicella-zoster virus (VZV) is a rare cause of encephalitis, but it can be associated with a rash, particularly in immunocompromised patients 3, 4, 5
- The presence of atypical lymphocytes in the cerebrospinal fluid can be a diagnostic clue for VZV encephalitis 4
- Treatment of viral encephalitis depends on the specific virus, but acyclovir is commonly used for herpes simplex encephalitis and VZV encephalitis 2, 6
- Antiviral therapy can reduce neurological morbidity in patients with VZV encephalitis, and vaccination against varicella and herpes zoster can prevent CNS infection 5
- Immunocompromised patients are at higher risk of developing VZV encephalitis and may present with cutaneous lesions 3, 5
- The clinical presentation of VZV encephalitis can vary, but it often includes meningitis or encephalitis, and pleocytosis in the cerebrospinal fluid is commonly observed 5