Focal perivascular alterations of white matter in herpes simplex encephalitis--a histological and immunocytochemical study.

Several cases of human herpes simplex encephalitis treated with Vidarabin have been investigated with the histological and immunocytochemical techniques. Cases with a subacute evolution revealed areas of focal perivascular myelin destruction in the white matter. The distribution of herpes simplex antigen did not show any preferential localization of the virus in perivascular oligoglial cells. In contrast, a spatial and temporal relationship has been found between the appearance of immunoglobulin-bearing cells around the vessels and that of areas of focal perivascular myelin damage. Therefore, it is postulated that the areas of focal destruction of myelin are not related to the cytotoxic effect of the virus but are rather dependent on the immune response of the host.