Cortical resections for intractable epilepsy of extratemporal origin: experience with seventeen cases over eleven years.

Seventeen patients underwent surgery between 1981 and 1990 for intractable partial epilepsy arising outside the temporal lobe. Twelve had frontal seizure onset, two parietal, two occipital and one diffusely in the hemisphere. Localization was achieved using extraoperative electrocorticography (ECoG) in five cases and intraoperative ECoG was employed in 12. Fifteen patients underwent cortical resections, but two did not subsequently have a resection. Both of these had porencephalic cysts. Of the 15 who had resections six (40%) were seizure free after a mean of 7.3 years. One (7%) was almost seizure free, six (40%) had worthwhile improvement. Pathological examination revealed oligodendroglioma in three, recurrent meningioma in one, vascular malformations in two, glial hamartoma in one and gliosis in six. One case with gliosis initially was shown to have an underlying malignant astrocytoma 2 years later. All these patients had CT abnormalities prior to surgery. Two patients (13%) had no worthwhile improvement. Pathology in these two was ischaemic neurons and arachnoid thickening. Both had normal CT findings preoperatively. One patient had an increased hemiparesis postoperatively. There were three cases of postoperative infection. It is concluded that extratemporal resection can achieve good results for seizure control and intraoperative ECoG is an effective technique for localizing the epileptogenic area. The presence of a structural lesion carries a particularly favourable prognosis for seizure outcome and surgery should, therefore, be strongly considered in patients with intractable partial epilepsy who have evidence of underlying structural pathology.