Surgical aspects of temporal lobe epilepsy. Results and problems

The Montreal Neurological Institute's experience with cortical resection for medically refractory temporal lobe epilepsy had grown to 1,102 patients as of the end of 1978, 932 in the non-tumoral category and 170 patients with tumors, including a few major vascular malformations. Follow-up data, (complete to date or to the patients' death in over 80% of the patients) shows that 70% of those with 2 or more years of adequate follow-up data (median period 11 years) have experienced a complete or nearly complete reduction of the seizure tendency. Since the attack pattern frequently does not give evidence as to the lateralization of the epileptogenic area, special EEG techniques are often required to select those patients apt to benefit from temporal lobectomy. Sphenoidal recordings with chronically implanted fine wire electrodes have been particularly useful. Telemetry has enhanced the capability of recording a large number of epileptic spikes during sleep and various daytime activities and of recording spontaneous attacks. An automatic spike detection gadget gives promise of major help in analyzing these lengthy records. The addition of a video tape system, correlated with the EEG telemetry system, aids in determining the side of origin of the seizures. A small number of patients in whom this could not be determined with these various EEG techniques, were studied with stereotactically implanted chronic depth electrodes employing a modification of the Talairach-Bancaud technique. Over 3/4 of these patients were shown to have the onset of their seizures to be sufficiently well lateralized to warrant temporal lobectomy.