Abstracts

High-resolution brain MRI is one of the most important criteria to help predict outcome after anterior temporal lobectomy (ATL). While a non-localizing pre-operative MRI often portends a poorer outcome for patients undergoing epilepsy surgery, successful surgical outcome is dependent upon convergence of the pre-operative assessment. We evaluated concordance of the pre-operative evaluation between 2 different epilepsy centers for patients with intractable localization-related epilepsy (LRE) undergoing ATL with a normal high-resolution brain MRI. Two epilepsy centers in the southeastern US (FL and NC) will be compared for concordance and outcome following ATL for medically intractable LRE. All patients had normal medial temporal structures utilizing a high-resolution brain MRI with a dedicated epilepsy protocol. The presence of febrile seizures, unilateral anterior temporal interictal epileptiform discharges (IEDs) [gt]80%, localized ictal EEG, localized PET/ictal SPECT, and asymmetric Wada results will be analyzed for concordance in those patients seizure-free (SF) and those not seizure-free (NSF). Thus far, information from 19 females and 13 males with a mean age of 35.2 years from one center (FL) analyzed after ATL following a normal high-resolution brain MRI has been completed. Twenty-one of 32 patients (65.6%) were SF after a mean of 1.20 years. Nine of the 32 patients required intracranial EEG (33.3%) with 4/9 (44.4%) SF (2 patients had [gt]1 surgery).
No significant predictability for a SF outcome was evident from any single pre-operative criteria, though a trend existed for IEDs and ictal EEG. Eighteen of 21 (85.7%) SF patients had a mean of at least 3 localizing criteria compared with 6/11 (54.5%) of patients that were NSF. Seizure-free patients had a mean of [gt]3 convergent pre-operative criteria, while those NSF had mean of [lt]3 localizing criteria. Variance for those patients SF was small (.0001; S.D.=.01) and greater for those patients NSF (.18; S.D.=.42). Temporal lobectomy is a favorable option for patients with refractory LRE even when high-resolution brain MRI is normal. Patients with greater than 3 convergent criteria for localization, independent of a normal brain MRI, were more likely to become SF following ATL.