Abstracts

Rationale: The role of the orbito-frontal region (OFR), also called the basal frontal lobe, in the generation of seizures is poorly characterized. Reasons include the lack of a characteristic semiology, electroencephalographic findings, inaccessibility of this region to surface electrodes and the resulting need for invasive recordings in order to demonstrate ictal onset within the orbito-frontal region. Surgical experience with resections restricted to the basal frontal area is limited. In our review of the published literature, only 23 resections of the OFR for epilepsy have been described, and only 10 of these were seizure free following resection. Methods: In a consecutive series of 65 patients undergoing surgical management of epilepsy between 10/2004 and 4/2008, 29 underwent invasive electrophysiology. Five of these cases were found to have OFR involvement in their epilepsy by placement of an electrode array over the basal frontal region (Fig 1). We review these cases to characterize the biology of OFR epilepsy and outcomes following surgical management more completely. Results: Average age at surgery was 45 years. Three patients had undergone prior temporal lobectomy, with unsuccessful seizure control. Two had prior history of traumatic brain injury with evidence of gliosis of the OFR on MRI. The other three had non-lesional imaging. Three patients underwent OFR resections in isolation, two underwent a concurrent resection of the posterior neocortical zones that were also shown capable of independent ictal genesis. Follow-up data are available for all, but relevant in 4 cases, as the last case is only three months post-op. In the 4 cases where longer follow-up is available (average 12 months), two of these patients are seizure free; one has a Weiser class 4 and one has a Class 5 outcome Conclusions: Given its intimate relationship with medial temporal lobe structures, the OFR may be closely linked with ictal onsets in patients with temporal lobe epilepsy (cryptic dual pathology) or may be the ictal onset zone. Given the protean clinical and elctro-physiological manifestations of epilepsy originating here, the OFR deserves close attention in patients who fail temporal lobectomies and in those with atypical electrophysiology who have imaging findings of hippocampal sclerosis.