Role of the Wada test in predicting cognitive outcome after temporal lobectomy

The Wada test and standardised neuropsychological measures are used to identify patients at risk of postoperative cognitive decline following temporal lobectomy. Given that the Wada test is an invasive procedure it is important to determine whether any information it provides is clinically unique. Data was considered from 54 patients who had undergone temporal lobectomy (TL) from either the language-dominant (n = 24) or non language-dominant (n = 30) hemisphere, and who had pre and postoperative neuropsychological assessment and magnetic resonance imaging (MRI). A subset of the sample also had a bilateral Wada test (n = 28). The results showed that baseline score was a significant predictor of postoperative naming and word pair recall for both TL groups, and recall of prose passages for the nondominant TL group. Side of resection predicted both verbal and visual memory outcome. Although Wada scores also predicted postoperative naming and verbal memory outcome, there were no significant differences in the number of patients classified correctly when the Wada scores were removed from the regression equation. In conclusion, in this sample of patients it appears that the Wada test does not add unique predictive information to the pre-surgical investigations with respect to prediction of cognitive outcome.