Abstracts

Rationale: Mesial temporal sclerosis (MTS), a common pathological finding of unknown origin in intractable temporal lobe epilepsy (TLE), may have multiple etiologies. Recent studies have shown that a substantial portion of patients with MTS have evidence for persistent infection with human herpes virus 6B (HHV-6B). No evidence for virus was found in patients with other epilepsy etiologies such as tumors or arteriovenous malformations. Since differences in etiology might affect surgical outcome after temporal lobectomy, we compared the postoperative course of patients with TLE and MTS with and without persistent HHV6B infection.Methods: Twenty-five patients with intractable TLE had standard anterior temporal lobectomy, with MTS on pathological examination, and were followed for at least one year without antiepileptic drug regimen changes. Hippocampal specimens were tested for HHV6B using PCR, Western Blot, and in situ immunohistochemistry. Surgical outcome was recorded by investigators blinded to HHV6B status. Febrile seizure history was obtained retrospectively. Results: Sixteen patients had HHV6B viral DNA in hippocampal tissue, and nine were negative. Thirteen of sixteen HHV6B +, compared with four of nine negative patients, were seizure-free (Chi-square 3.59: p <0.06). HHV6B negative patients showed trends toward earlier onset age, longer duration, and smaller hippocampi ipsilateral to the seizure focus. There was no difference in the incidence of febrile seizures by history. Conclusions: This study suggests that there may be multiple etiologies for MTS. Patients with persistent HHV6B infection may have more indolent disease and better temporal lobectomy prognosis.