Comparison of preoperative measures in predicting cognitive outcome after temporal lobectomy

Objective: The pre-surgical evaluation of epilepsy patients often includes the Wada test; however, debate continues regarding its ability to predict material-specific memory functioning after temporal lobectomy. Less invasive tests, such as standard neuropsychology, may provide as much information as the Wada in the majority of patients. The aim of this project is to investigate whether the Wada provides additional information to neuropsychology measures in predicting cognitive outcome post temporal lobectomy at both the group and individual level. Participants and Methods : Subjects comprise 37 patients who had undergone a temporal lobectomy (Left: n= 20; Right: n= 17), and who had a preoperative neuropsychological assessment, a bilateral Wada test, and a postoperative neuropsychological assessment at least 6 months following surgery. The Wada protocol used was based on that of the Cleveland Clinic Foundation, and involved memory for objects, line drawings of objects, abstract words and abstract designs. Results : Results obtained for the WMS-III, WMS-R and BNT indicated that the preoperative neuropsychological scores, but neither Wada score (ipsilateral or contralateral), were significant predictors of postoperative change (controlling for test-retest effects). A higher level of preoperative performance was associated with greater decline post-surgery. Further exploration of the data indicated that neither Wada score correlated with outcome on a comprehensive battery of tests. Conclusions : Preliminary results suggest limited utility of the Wada test for predicting memory outcome. Comparison of the predictive ability of the various neuropsychological measures will also be explored.