Abstracts

The aim of the study was to assess the surgical outcome with those MRI- negative temporal lobe epilepsy patients who underwent preoperative evaluation with invasive intracranial electrodes. Since 1988 Kuopio University Hospital has served as a national center for adult epilepsy surgery in Finland (population 5.3 million). From January 1990 to October 2003 altogether 132 patients with medically refractory epilepsy has been evaluated with intracranial EEG monitoring, and 120 of them had suspected temporal lobe epilepsy. Of the 120 patients, 60 had normal MRI findings and 39 of them were operated determined by the results of invasive monitoring. The surgical outcome in these 39 patients was assessed according to Engel[apos]s classification at one year postoperative follow-up. The reasons for not to proceed to operative treatment was analysed among those 21 patients who were considered inoperable. Twelve patients (30.8 %) were seizure free at 1- year follow-up (Engel[apos]s class I) and three patients (7.7 %) had rare seizures (Engel[apos]s class II). Nine patients (23.1 %) had worthwhile improvement (Engel[apos]s class III) and fifteen patients (38.5 %) did not benefit from the surgery (Engel[apos]s class IV). Of those 21 inoperable patients, 7 patients (33.3 %) had inadequately localised extratemporal onset of the seizures and 5 patients (23.8 %) had bitemporal onset of the seizures. Two patients (9.5 %) had seizure onset near Wernicke[apos]s area and with two patients (9.5 %) the frontotemporal differential diagnostics was not possible to demonstrate. The other five patients (23.9 %) did not either get seizures during monitoring, were seizure free after registration or had generalised epilepsy. It is possible to achieve satisfactory surgical outcome with this diagnostically challenging subgroup of MRI negative patients with temporal lobe epilepsy who underwent intracranial monitoring. On the other hand, with those patients who did not benefit from surgical treatment, the predicting factors for outcome need to be further analysed. (Supported by Academy of Finland, the North-Savo Regional Fund of the Finnish Cultural Foundation, the Kuopio University Hospital Research Fund (EVO Fund 577 27 19), the University of Kuopio and the Vaajasalo Foundation.)