Herpes simplex encephalitis treated with vidarabine (adenine arabinoside).

Vidarabine, an antiviral chemotherapeutic agent shown to have in vitro activity against the herpes group of viruses, was administered to five patients with brain biopsy-proved herpes simplex virus encephalitis. The mortality in this small number of patients (one of five or 20%) was less than that in most published reports of patients receiving other treatment modalities or no treatment other than supportive measures. No apparent toxicity was found that was attributable to vidarabine. Neuropsychological impairment of varying degree was noted in four surviving patients tested at two months after treatment and again 12 to 21 months later. Progressive improvement had occurred in three.