Multiple subpial transection for control of epileptic seizures: effectiveness and safety.

PURPOSE: To assess the efficacy and safety of multiple subpial transection (MST), a new technique in epilepsy surgery, alone and in combination with resection.

METHODS: MST was performed in 22 patients with intractable epilepsy, 10 of whom were treated with a combination of a resection and MST in functionally important cortex, 6 of whom were treated with a combination of a resection and MST performed outside functionally important cortex, and 6 of whom were treated with MST alone.

RESULTS: Of the 6 patients who received MST alone, none became seizure free and 4 showed > 50% reduction of all seizure types. In 2 patients, including 1 with Rasmussen's encephalitis, no change in seizure frequency or intensity occurred. Of the 16 patients in whom MST was combined with a resection, 9 (56%) became seizure free. Six of the remaining 7 patients showed > 95% reduction of all seizure types. Disappearance of epileptiform potentials in the postoperative EEG correlated significantly with complete relief from seizures. Subtle, permanent neurological deficits remained in 5 of 14 patients who received MST in functionally important brain areas.

CONCLUSIONS: Reduction of the seizure frequency was substantial in 4 of 6 patients who received MST alone, but complete seizure control was not observed. MST surrounding a lesionectomy may be a new surgical approach which would minimize the excised volume and improve seizure control.