[Central nervous system infection due to Herpes simplex virus in AIDS]

Infections of the central nervous system by Herpes simplex viruses (Herpes simplex type 1 and Herpes simplex type 2) are uncommon in acquired immune deficiency syndrome and are often clinically and pathologically atypical. We have collected 11 cases of herpes simplex encephalomyelitis in AIDS patients reported in the literature. Only 3 of these cases presented with a typical, necrotizing, limbic encephalitis. Other clinicopathological patterns included ventriculitis, rhombencephalitis and myelitis. Ventriculitis and rhombencephalitis were usually due to infection by HSV-1, whereas myelitis was mostly due to HSV-2 infection. Distinction between the 2 types of virus is often difficult by immunohistochemistry due to frequent cross reactivity and usually requires tissue culture, in situ hybridization, or polymerase chain reaction. Association of HSV encephalomyelitis with productive infection of the central nervous system by the human immunodeficiency virus was only found in one case. In contrast, co-infection with cytomegalovirus was found in 9 of the 11 cases. One case also had had varicella zoster virus vasculitis, and another case also had a cerebral malignant non Hodgkin's lymphoma in which Epstein Barr virus genome was identified. This supports the view that concomitant herpes-virus infections of the central nervous system is a characteristic feature of AIDS.