RESULTS OF CORTICAL RESECTION FOR INTRACTABLE EPILEPSY USING INTRAOPERATIVE CORTICOGRAPHY WITHOUT CHRONIC INTRACRANIAL RECORDING

Twenty-four patients with intractable partial epilepsy underwent surge ry 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 fro ntal. Craniotomy was undertaken with intraoperative electrocorticograp hy (ECoG). Ten cases had a standard temporal lobectomy, seven a topect omy, 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 le ngth of follow-up was 7.4 years. Fourteen patients (64%) were seizure free, two (9%) almost seizure free, four (18%) had worthwhile improvem ent and two (9%) no improvement. Of the temporal resections, 9 out of 12 (75%) were seizure free and of the extratemporal resections 5 out o f 10 (50%) were seizure free. Removal of a mass lesion carried the mos t 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 gliosi s were seizure free. In two of the frontal resections removal of tumou r resulted in disappearance of contralateral frontal independent spike s. It is concluded that where sufficient information exists to localiz e seizure activity by non-invasive means, invasive recording is unnece ssary. The utility of intraoperative ECoG is discussed. It may be of l imited use in cases of standard resection or when a mass lesion is pre sent, but ECoG can prove useful to delineate the epileptogenic area in cases where there is no mass lesion and the results can still be rewa rding.