Invasive diagnostics and resective surgery in frontal lobe epilepsy

Frontal lobe epilepsy is the most common extratemporal epilepsy syndrome representing the second most common focal epilepsy after temporal lobe epilepsy. Due to its large anatomical area and involvement of different functional zones, such as the supplementary motor area, Broca's area and premotor cortex, the semiology of frontal lobe seizures can represent a diagnostic challenge. Anatomical connections to the insula or corpus callosum may hamper the electrophysiological localization of the seizures as well. Additionally, the frequent absence of a visible epileptogenic lesion, makes the implantation of deep and/or subdural electrodes as part of the presurgical diagnostics indispensable in many cases. The spectrum of surgical resections in the frontal lobe ranges from simple focal or extended lesionectomy to frontal lobe disconnection and frontal lobectomy. The postoperative seizure outcome differs immensely, with seizure-free rates ranging from 20% to 70%. The present article presents a review of invasive work-up and surgical strategies for frontal lobe epilepsy. In addition, postoperative results and factors influencing seizure outcome are summarized to point out that frontal lobe epilepsy remains a surgical challenge that may be better solved by future advances in imaging or neuromodulation.