Multiple subpial transection: a review of 21 cases.

Multiple subpial transection (MST) is a novel technique in surgery for epilepsy, employed in patients where some or all of the epileptogenic zone cannot be resected because it lies in a vital cortical area. Twenty one patients subjected to MST were reviewed. Eighteen patients had medically intractable epilepsy and three patients had Landau-Kleffner syndrome. Their ages ranged from 6 to 47 (mean 15-9) and duration of epilepsy ranged from 0.33 to 42 (mean 8.6) years. Preoperative MRI showed focal abnormalities in eight cases. Detailed electrophysiological examination was carried out on all patients. Brain resection was performed in addition to MST in 12 patients. A further six patients underwent brain biopsy. Three patients with Landau-Kleffner syndrome were subjected neither to resection nor to biopsy. Histopathological examination showed Rasmussen's syndrome in six patients, cortical dysplasia in six, cerebral tumour in one, and non-specific changes in five. Multiple subpial transection was carried out mainly in precentral and postcentral regions. Eighteen patients have been followed up for one to five years, and three for 10 months. The three patients with Landau-Kleffner syndrome were mute before operation and have shown substantial recovery of speech. Of the other 18, 11 showed a worthwhile decrease in seizure frequency. None of the patients developed chronic neurological deficits attributable to MST. It is concluded that MST leads to worthwhile seizure control without major neurological deficit in patients who would otherwise be inoperable.