Usefulness of Wada test in predicting seizure outcome following anterior temporal lobectomy

Objective: To study the usefulness of the Wada test for predicting seizure outcome following anterior temporal lobectomy (ATL). Methods: From 1996 to 2002, all patients with left mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS) and selected patients with right MTLE-HS underwent the Wada test before ATL at our center. Patients were selected for ATL on the basis of unilateral HS on MRI and concordant electro-clinical data. Twelve-item recognition paradigm was used for Wada memory testing. Score of +1 was awarded for a correct response and -0.5 for an incorrect response. We defined Wada failure as a contralateral score of <5, ipsilateral score of >8, and difference score of <0. No patient was denied surgery based on the Wada results. Means of the three scores were compared between seizure free and non-seizure free patients. Sensitivity, specificity and receiver operator characteristic curves of various scores for predicting seizure outcome were calculated. Results: 151 patients (129 left MTLE; mean age: 27.80 +/- 8.72 years) formed the study group. At mean postoperative follow-up of 6.4 +/- 2.0 years, 127 patients were seizure free. Mean contralateral score was lower in the seizure-free group (7.15 +/- 3.07 vs. 8.71 +/- 4.13; p < 0.001) while ipsilateral and difference scores were similar between the two seizure outcome groups. Areas under the curves for contralateral, ipsilateral and difference scores for predicting seizure-free outcome were 0.49, 0.58 and 0.59, respectively, suggesting its modest usefulness in individual patients. Results remained same when the analysis was restricted to left MTLE patients. Conclusions: Wada test has limited usefulness for predicting seizure outcome following ATL. (C) 2013 Elsevier B.V. All rights reserved.