CHRONIC ENCEPHALITIS AND EPILEPSY (RASMUSSEN ENCEPHALITIS) - DETECTION OF CYTOMEGALOVIRUS AND HERPES-SIMPLEX VIRUS-1 BY THE POLYMERASE CHAIN-REACTION AND IN-SITU HYBRIDIZATION

We made a pathologic diagnosis of chronic encephalitis on surgical res ections or autopsy material in 10 patients with intractable seizures a nd studied the specimens by immunohistochemistry for herpes simplex vi rus (HSV) I and 2 and cytomegalovirus (CMV) as well as by the polymera se chain reaction (PCR) for Viral DNA sequences (HSV1, HSV2, and CMV). We also assessed eight patients (nonepileptic) with pathologically do cumented or clinically suspected encephalitis and five resections from epileptics without encephalitis. Immunohistochemistry for viral antig ens was negative in all cases. Using PCR assay, CMV was present in six and HSV1 in two of 10 epilepsy patients with chronic encephalitis. We demonstrated CMV by in situ hybridization in two of the six patients positive for CMV by PCR. We found no viral sequences by PCR in five ep ileptics without encephalitis. Of the eight patients (nonepileptic) wi th clinically suspected or pathologically confirmed encephalitis, two cases showed CMV sequences by PCR. These observations suggest that PCR allows detection of viral sequences in some cases of chronic encephal itis associated with epilepsy that may be missed by in situ hybridizat ion.