Orbitofrontal Epilepsies: Intracranial Electroencephalography and Surgical Aspects

Abstract

Orbitofrontal epilepsies (OFE) produce variable clinical semiologies and nonspecific electrographic patterns thereby being challenging to localize. Furthermore, systematic studies of the surgical management and outcomes in OFE are sparse. The authors review the current literature and discuss the intracranial electroencephalography, microsurgical techniques, and surgical outcomes of patients in the context of a 20-year surgical experience in treating 24 patients with OFE. The authors distinguish between purely orbitofrontal resections (OF-focal, n = 10) and those in whom additional brain regions were concurrently resected (OF-plus, n = 14). These two cohorts were similar with respect to age, duration of epilepsy, and presence of an OF lesion on MRI. Patients frequently reported no auras (OF-focal: 7 [70%], OF-plus: 8 [57%]); generalized tonic-clonic seizures were common (OF-focal: 6 [60%], OF-plus: 7 [50%]); and seizures were often nocturnal (OF-focal: 5 [50%], OF-plus: 8 [57%]). Surgical extensions among the OF-plus group included the prefrontal or frontal pole (67%), temporal pole (11%), and mesial temporal lobe (22%). Durable Engel I to II outcomes at last follow-up (median: 4 years, interquartile range [IQR]: 2-7) were achieved in 5 patients (50%) with OF-focal epilepsies and 8 (57%) patients with OF-plus epilepsies. Among nonlesional cases, 4 of 11 patients (36%) achieved seizure freedom, of whom 3 (75%) underwent OF-plus resection. The most common etiology was malformation of cortical development (58%). Surgical resection of the OFE carries the same seizure-free rates as other neocortical epilepsies and can be done safely with minimal cognitive or functional decline.