Viral encephalitis is a medical emergency. The spectrum of brain involvement and the prognosis are dependent mainly on the specific pathogen and the immunological state of the host. Although specific
therapy is limited to only several viral agents, correct immediate diagnosis and introduction of symptomatic and specific
therapy has a dramatic influence upon survival and reduces the extent of permanent
brain injury in survivors. We searched MEDLINE (National Library of Medicine) for relevant literature from 1966 to May 2004. Review articles and book chapters were also included. Recommendations are based on this literature based on our judgment of the relevance of the references to the subject. Recommendations were reached by consensus. Where there was lack of evidence but consensus was clear we have stated our opinion as good practice points. Diagnosis should be based on medical history, examination followed by analysis of cerebrospinal fluid for
protein and
glucose contents, cellular analysis and identification of the pathogen by polymerase chain reaction (PCR) amplification (recommendation level A) and serology (recommendation level B). Neuroimaging, preferably by magnetic resonance imaging, is an essential aspect of evaluation (recommendation level B). Lumbar puncture can follow neuroimaging when immediately available, but if this cannot be obtained at the shortest span of time it should be delayed only in the presence of strict
contraindications. Brain biopsy should be reserved only for unusual and diagnostically difficult cases. All
encephalitis cases must be hospitalized with an access to intensive care units. Supportive
therapy is an important basis of management. Specific, evidence-based, anti-viral
therapy,
acyclovir, is available for
herpes encephalitis (recommendation level A).
Acyclovir might also be effective for varicella-zoster virus
encephalitis,
gancyclovir and
foscarnet for cytomegalovirus
encephalitis and
pleconaril for enterovirus
encephalitis (IV class of evidence).
Corticosteroids as an adjunct treatment for acute
viral encephalitis are not generally considered to be effective and their use is controversial.
Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management.