Patients with refractory epilepsy treated using a modified multiple subpial transection technique.

BACKGROUND : Multiple subpial transection (MST) is a potential surgical treatment for patients with epileptogenic foci located in cortical areas with higher functions. As neurosurgical teams have become more experienced with MST, the original technique has adapted. OBJECTIVE : To report our 6-year experience with a modified MST technique. METHODS : The population included 62 consecutive patients with medically refractory epilepsy treated by MST, with a follow-up period ranging from 2 to 9 years. MST was performed on gyri under neuronavigation and guided by intraoperative electrocorticography. We performed radiating MST from a single cortical entry point. The MST technique was described according to the number of transections performed and the Brodmann areas (BAs) involved. Any MST-related complications were registered and followed up. Clinical outcome was described in terms of seizure suppression or reduction according to the Engel modified classification. RESULTS : Twelve patients underwent MST alone (MSTa), and 50 had MST with another procedure. The main MST sites were BA 4 (61%) and 3, 1, 2 (58%); in 22% of cases, MST was performed in BA 44, 22, 39, and 40. Permanent neurological deficits were observed in 4 (6.4%) patients; 2 minor deficits were MST related (3.2%). A reduction in the seizure rate of at least 50% was seen in 79% of patients (MSTa group, 75%), and 42% became seizure free (MSTa group, 33%). CONCLUSION : This study demonstrates the efficacy and low morbidity of radiating MST performed under neuronavigation and intraoperative electrocorticography. ABBREVIATIONS : BA, Brodmann areaEEG, electroencephalogramFDG, 18-fluorodeoxyglucoseioECoG, intraoperative electrocorticographyMRE, medically refractory epilepsyMST, multiple subpial transectionMSTa, multiple subpial transection aloneMST+, multiple subpial transection with other procedures.