Chapter 23 - Usefulness of the Wada Test in Mesial Temporal Lobe Epilepsy

Abstract

This chapter discusses the usefulness of the Wada test in mesial temporal lobe epilepsy. The Wada test, or intracarotid amobarbital procedure, is an essential part of the preoperative evaluation for anterior temporal lobectomy at most epilepsy surgery institutions. The results from Wada testing and functional cortical mapping with electrical stimulation, another inactivation approach to identify brain function, are not always in complete agreement. Decreased memory performance following contralateral injection is a robust phenomenon that has been reported with many different approaches to Wada testing. Wada memory results are also associated with a variety of quantitative measures of hippocampal structure. Patients with severe hippocampal cell loss are more likely to fail the Wada memory test following injection contralateral to the seizure onset than patients with less severe hippocampal pathology. It is found that due to differences in approaches and conceptualizations, the application of Wada testing has not been uniform across institutions. It is suggested that Wada memory testing provides valuable information to confirm seizure onset laterality, and thereby decrease the need for additional monitoring.