Abstracts

Long-term outcome data from cases of focal onset intractable epilepsy treated with multiple subpial transection (MST) alone is very limited. Questions to be answered from this patient group include the efficacy of the procedure as a stand-alone procedure without resection, the duration of MST efficacy, and possible long-term side effects of MST. From our epilepsy surgery database of over 700 cases, 9 cases were identified in which MST was the only procedure performed in the treatment of medically intractable epilepsy. A restrospective review and phone contacts were performed. Eight males and one female had an age range of 11-42 (median 16 years), and a preoperative seizure frequency between 2-450 (median 45) seizures/month. MRI or CT was normal in 7 of 9 patients. Metabolic imaging was performed in 5 patients and was localizing in only 2. Long-term follow up ranged from 2-15 years. At last follow-up, median 8 years, seizure outcome was as follows: Engel[rsquo]s class I-2, II-4, III-1, IV-2. At two years, outcome was I-3, II-3, III-2, IV-1. No patient developed a new seizure type. Permanent deficits were seen in 1 of 9 patients. In this case series, we present the longest follow-up on MST in the literature. Long term follow up on cases of pure MST demonstrates efficacy as a stand-alone procedure in select patients. In long term follow up, this efficacy remained stable in most patients. In this series of pure MST, no unexpected late onset sequellae were noted.