Late Seizure Recurrence after Multiple Subpial Transections *Darren Orbach, ²Pantaleo Romanelli, *²Orrin Devinsky, and ²Werner Doyle Departments of *Neurology and ²Neurosurgery, NYU School of Medicine, New York, New York, U.S.A. Summary: We studied long-term outcome (range, 28–89 months; mean, 56 months) after multiple subpial transections (MSTs) for medically refractory epilepsy. Forty-three (79.6%) of 54 patients had a consistent significant reduction in seizure frequency, and 27 (50%) of the 54 were either entirely seizure free or virtually so. However, 10 (18.6%) patients sustained an increase in seizure frequency several years after surgery, after showing initial postoperative improvement. This suggests that late seizure recurrence is a more important problem in cases in which MST has been performed than for pure resections. Key Words: Intractable seizures—Epilepsy surgery—Multiple sub- pial transections—Resection. Morrell et al. (1) developed multiple subpial transec- tions (MSTs) to surgically treat intractable epilepsy with seizure foci in primary sensorimotor or language areas. Given the columnar organization of cerebral cortex, ver- tical transections should theoretically disrupt only hori- zontally oriented axons while preserving the vertically oriented architecture and cortical function. Although MSTs appear effective (2–5), long-term outcome data are not available. After standard cortical resection for intractable epi- lepsy, patients’ postoperative outcome can be largely predicted by their status 2 years after surgery (6,7). Sev- eral small series (2–5) have reported on seizure outcome after MSTs, followed up for 2 years postoperatively. We report here on our long-term follow-up of a large cohort of MST patients. METHODS Fifty-four patients with medically refractory epilepsy had presurgical evaluation with video-EEG, neuropsy- chological testing, Wada testing, and magnetic reso- nance imaging (MRI), supplemented with ictal/interictal single-photon emission computed tomography (SPECT), positron emission tomography (PET), or magnetoen- cephalography (MEG). After subdural grid and strip placement and occasionally depth electrodes, cortical mapping was done to identify primary sensorimotor or language cortex. If a seizure focus was found to be over- lying eloquent cortex, MSTs were made. Three patients had MSTs alone; 51 patients with lesions partially local- ized to noneloquent cortex had both resections and MST. An attempt was made in each of these 51 cases to limit the resection to cortex that was demonstrably epilepto- genic on EEG monitoring. Fourteen (25.9%) patients had very small resections involving at most a single gyrus or a tumor, and 37 (68.5%) patients had resections involv- ing much or all of a cortical lobe. Details concerning patient selection, presurgical evaluation, and the place- ment of MSTs are discussed elsewhere (4). We excluded patients with a progressive neurologic disorder from this analysis. Patients were followed up for an average of 55.8 months after surgery (range, 28–89 months). All patients were continued on antiepileptic medication (AEDs) im- mediately postoperatively, but their regimens were indi- vidualized over time based on their clinical status, ranging from eventual discontinuation of medication to the use of experimental AEDs or vagus nerve stimulator implantation, as appropriate. RESULTS Outcome is expressed using a modified Engel scale: grade I, patients are seizure free or had only nondisabling simple partial seizures; grade II, rare seizures (>85% reduction); grade III, >50% reduction in seizure fre- quency; and grade IV, no meaningful reduction in sei- zure frequency. Grade I outcome was achieved in 37%, grade II in 13%, grade III in 29.6%, and grade IV in 20.4% of patients. Three patients in our cohort had MSTs alone, with one patient in each of grades I, II, and IV. Several temporal patterns were apparent. Two (3.7%) patients had a higher frequency of seizures during the Revision accepted June 4, 2001. Address correspondence and reprint requests to Dr. O. Devinsky at NYU-Mount Sinai Comprehensive Epilepsy Center, 403 E. 34th St., New York, NY 10016, U.S.A. E-mail: od4@is4.nyu.edu Epilepsia, 42(10):1316–1319, 2001 Blackwell Science, Inc. © International League Against Epilepsy 1316