Orbitofrontal Epilepsy: Case Series and Review of Literature (P6.341)

OBJECTIVE To better characterize orbitofrontal epilepsy. BACKGROUND Temporal lobe epilepsy is the most common and studied focal refractory epilepsy. Orbitofrontal epilepsy is less known, possibly unrecognized. DESIGN/METHODS A) Retrospective chart analysis of orbitofrontal epilepsy cases investigated in 6 epilepsy monitoring units between 1988-2014; B) Exhaustive review of all case reports of orbitofrontal epilepsy in literature from 1972-2014. Diagnosis was confirmed by the presence of an orbitofrontal epileptogenic lesion or seizure-freedom following orbitofrontal resection. RESULTS Seventeen cases (7M/10F; mean age 33 yo(8-51); mean age of onset 14.5 years) were identified. Semiologically, 4(24[percnt]) experienced auras, 2(11[percnt]) had a fear component, 11(65[percnt]) were dyscognitive, 11(65[percnt]) experienced gestural motor behaviors, 6(35[percnt]) had verbal automatisms. Scalp EEG interictal epileptiform discharges were localized to the frontal, temporal or fronto-temporal leads, lateralized or predominating ipsilaterally. 3/10(30[percnt]) and 1/5(20[percnt]) of patients had a localizing PET or ictal SPECT study, respectively. Out of the 15 patients who eventually underwent surgery, 8 had a lesion on MRI, all had a favourable outcome (66[percnt] Engel 1; 34[percnt] Engel 2; mean FU 5 years). Pathological analysis of 14/15 of the resected specimen revealed: focal cortical dysplasia (9), low grade glioma (1), cavernoma (1), oligodendroglial hyperplasia (1) and normal (2). Our review of the literature identified only 31 cases where orbitofrontal epilepsy could be confidently established. CONCLUSIONS To our knowledge, this is largest orbitofrontal epilepsy series reported. Overall, auras are infrequent and mostly non-specific, generally with altered consciousness, motor gestural behaviors and verbal automatisms. Interictal epileptiform discharges are mainly over the frontal and temporal leads. Ictal discharges are more diffuse. Surgical outcome is generally good but neuropsychological outcome is less well documented. Our findings are limited by the retrospective nature of our study. Disclosure: Dr. Chibane has nothing to disclose. Dr. Dubeau has nothing to disclose. Dr. Boucher has nothing to disclose. Dr. Phuoc has nothing to disclose. Dr. McLachlan has received personal compensation for activities with UCB Canada and Eisai Canada. Dr. Sadler has received personal compensation for activities with UCB Canada and EISAI Canada. Dr. Desbiens has nothing to disclose. Dr. Lionel Carmant has received research support from UCB Canada. Dr. Nguyen has nothing to disclose.