Role of electrocorticography at surgery for lesion-related frontal lobe epilepsy

Background: The prognostic significance of epileptiform activity (EA) recor ded intraoperatively at electrocorticography (ECOG) in patients with lesion -related frontal lobe epilepsy (FLE) is unknown. Methods: The results of EC OG performed in 22 patients with intractable FLE and a circumscribed fronta l lobe structural lesion were compared with postoperative seizure control, Three patients underwent re-operation for a total of 25 cases, 23/25 with p ost-resection ECOG, Lesions were neoplasms (12), hamartomas (6) and arterio venous malformations (4). Results: Outcomes were 15/25 Class I, 5/25 Class III and 5/25 Class IV (Engel classification). Class I outcome was associate d with pre-excision EA recorded from less than or equal to 2 gyri (p < 0.05 ) and absence of EA, or EA limited to the resection border, at post-excisio n ECOG (p < 0.01), Complete lesion excision was highly correlated with Clas s I outcome (p < 0.001). The most significant correlations were seen when E COG and lesionectomy variables were considered together: all 12 cases with complete lesionectomy and absent post-excision EA distant to the resection border had Class I outcome (p < 0.00015) and all 13 cases with complete les ionectomy and pre-excision EA recorded from less than or equal to 2 gyri ha d Class I outcome (p < 0.00005). Conclusions: Postoperative seizure control in lesion-related FLE is assured in the setting of complete lesion resecti on with pre-excision EA recorded from less than or equal to 2 gyri and no p ost-excision EA distant to the resection border; complete lesion excision i s of paramount importance.