CNS diseases associated with varicella zoster virus and herpes simplex virus infection. Pathogenesis and current therapy.

In recent years, herpes simplex virus has been recognized as an important CNS pathogen in neonates and adults. The recent development of effective antiviral therapy has substantially reduced the excessive morbidity and mortality associated with these infections. For neonatal herpes simplex infections, the current drug of choice is vidarabine. The results of ongoing clinical trials comparing vidarabine with acyclovir in neonatal herpes may lead to a change in the recommended therapy. In the adult, the therapy of choice for herpes simplex encephalitis is acyclovir. Although effective, the present therapies for herpes simplex infections of the CNS leave much room for improvement. In addition to the development of more effective antiviral drugs and less invasive diagnostic techniques, prevention of these often devastating infections will be important in reducing morbidity and mortality. The CNS diseases associated with varicella and herpes zoster may have a different pathogenesis. The implication for therapy in these diseases favors nonspecific supportive therapy in the varicella-associated syndromes. The few anecdotal reports of the use of vidarabine and acyclovir in herpes zoster encephalitis and the histopathologic evidence suggesting viral invasion of the CNS in many cases of zoster-associated neurologic syndromes makes the use of specific antiviral therapy in zoster encephalomyelitis more rational. However, appropriate therapeutic recommendations will have to be based on controlled clinical trials that have not yet been performed.