Cytosine arabinoside therapy for herpes simplex encephalitis--clinical experience with six patients.

Two neonates and four adults with herpes simplex virus (HSV) encephalitis were treated with cytosine arabinoside (Ara-C). A low dose of 40 to 160 mg per m(2) per day was given for 4 to 6 days by continuous intravenous infusion and, except in two cases, by intrathecal administration. In one patient, idoxuridine (IUdR) at the dose of 1 g every 4 h was also administered after 4 days of Ara-C therapy. Both neonates and two of four adults survived. Their clinical improvement was closely related in time to the onset of therapy with Ara-C (cases 1, 2, 3) and with IUdR (case 4). In one adult who died on the 27th day of illness of a massive pulmonary embolus, postmortem examination of the brain did not disclose viral inclusions, and viral culture was negative. In the other patient who died, however, brain culture postmortem was still positive for HSV despite 4 days of Ara-C therapy. Ara-C, in addition to IUdR, may be effective in HSV encephalitis treatment, but double-blind, controlled studies appear to be necessary with these agents.