Subacute encephalitis in acquired immune deficiency syndrome: a postmortem study.

Thirty-one out of 40 patients with the acquired immune deficiency syndrome examined at autopsy had significant central nervous system disease. A subacute encephalitis, found in 19 patients, was the most frequent finding and was characterized by marked brain atrophy and a progressive dementing illness. This entity is linked to cytomegalovirus (CMV) by typical histopathology and association with systemic CMV infection with supportive evidence of positive immunohistochemical staining of tissue sections and, in one case, identification of CMV-type viral particles by electron microscopy. However, brain tissue cultures have been negative, making the etiology of subacute encephalitis not entirely clear.