SURGICAL OUTCOMES IN PURE FRONTAL-LOBE EPILEPSY AND FOCI THAT MIMIC THEM

In this study we examined 37 subjects with a diagnosis of intractable frontal lobe epilepsy (FLE) based on non-invasive pre-surgical evaluat ion. Twenty-six underwent chronic intracranial ictal recordings (CIR) with video monitoring; 20 of these went on to surgical resection. Elev en underwent surgery without CIR. Retrospectively, we determined that 19 had pure FLE, 12 had frontal plus extrafrontal epileptogenic zones, and six others did not have FLE. We analysed the whole group and indi vidual categories to evaluate the determinants of surgical outcome. Si xty percent of the pure frontal group is seizure free with all having greater than or equal to 75% reduction. The frontal-plus group had onl y 10% seizure free with 70% having greater than or equal to 75% reduct ion. Being in the pure frontal group was associated with better outcom es than the 'frontal-plus' group (P < 0.05; chi-square). Subjects with FSIQ greater than or equal to 85, focal pathologies and (18)FDG-PET s cans which were normal or had focal abnormalities (P less than or equa l to 0.05, all, chi-square) were more likely to have excellent outcome s. MRI abnormalities, surface EEG, and location and size of resection were not predictive of surgical outcomes. Rasmussen's encephalitis, in complete surgical strategies and bilateral foci were apparent in those with poor outcomes, and surgical size predicted post-operative defici ts (chi-square; P < 0.001). We conclude that careful, hypothesis-drive n implants and operating procedures can result in good surgical outcom es for frontal lobe epilepsy subjects even when lesions are not appare nt on routine neuroimaging. (C) 1998 Elsevier Science B.V.