Results of cortical resection for intractable epilepsy using intra-operative corticography without chronic intracranial recording.

Abstract

Twenty-four patients with intractable partial epilepsy underwent surgery between 1969 and 1988. Localization was by non-invasive means using scalp EEG and CT. In 12 cases the focus was temporal and in eight frontal. Craniotomy was undertaken with intraoperative electrocorticography (ECoG). Ten cases had a standard temporal lobectomy, seven a topectomy, four topectomy with tumour excision and one tumour excision alone. Two cases did not have a resection. Pathology revealed a mass lesion in 12 cases, hippocampal sclerosis in two and gliosis in six. Mean length of follow-up was 7.4 years. Fourteen patients (64%) were seizure free, two (9%) almost seizure free, four (18%) had worthwhile improvement and two (9%) no improvement. Of the temporal resections, 9 out of 12 (75%) were seizure free and of the extratemporal resections 5 out of 10 (50%) were seizure free. Removal of a mass lesion carried the most favourable prognosis for seizure outcome: 10 out of 12 (83%) of the cases with mass lesions, but 3 out of 6 (50%) of the cases with gliosis were seizure free. In two of the frontal resections removal of tumour resulted in disappearance of contralateral frontal independent spikes. It is concluded that where sufficient information exists to localize seizure activity by non-invasive means, invasive recording is unnecessary. The utility of intraoperative ECoG is discussed. It may be of limited use in cases of standard resection or when a mass lesion is present, but ECoG can prove useful to delineate the epileptogenic area in cases where there is no mass lesion and the results can still be rewarding.