The Wada test in the evaluation for epilepsy surgery

Abstract

The Wada test is the standard part of the pre-operative evaluation for epilepsy surgery. The procedure involves the slow injection of sodium amobarbital (typically 100-500mg) into the internal carotid artery following a transfermoral approach. The amobarbital anesthetizes the anterior two-thirds of the ipsilateral cerebral hemisphere for approximately 5-10 minutes. During this period of hemispheric anesthesia, assessment of expressive and receptive language can establish cerebral language representation. In addition, the procedure provides a reversible model to assess the risk of significant memory change following surgery. This is important because patients undergoing surgery involving the temporal lobe may experience significant memory decline following surgical resection of a temporal lobe seizure focus. This paper will represent information about the use of Wada testing, and discuss issues involved in establishing cerebral language representation, lateralization of temporal lobe dysfunction, seizure and memory outcome prediction, and future directions of this technique.