Presence of human herpesvirus 6 and herpes simplex virus detected by polymerase chain reaction in surgical tissue from temporal lobe epileptic patients

We investigated the presence of human herpesvirus 6 (HHV-6) and herpes simp lex virus (HSV) in surgical tissue from temporal lobe epileptic patients. A total of 17 cases were studied, including eight males and nine females. Th e mean age was 24.9 +/- 11.1 years and the mean age of onset was 11.1 +/- 5 .4 years. Five patients were diagnosed as encephalitis/meningitis and anoth er three had a history of suspected encephalitis/meningitis, but no patient showed any obvious neurological symptom or mental handicap. Mesial and lat eral temporal tissues were examined by polymerase chain reaction. Among six patients positive for HHV-6 (35%), the mesial temporal lobe was positive i n four and the lateral temporal lobe was positive in three. Herpes simplex virus was positive in only one patient. Three of the six patients positive for HHV-6 did not show any apparent causes. Mild encephalitis/meningitis in duced by HHV-6, a condition sometimes not recognized as encephalitis/mening itis, may be one of the most frequent causes of temporal lobe epilepsy.