The Wada test

Abstract

To examine the current clinical indications for conducting a Wada test in the presurgical evaluation of epilepsy surgery candidates in the light of research on the reliability and validity of proposed, noninvasive alternatives.

There has been a significant shift in the role of the Wada test in epilepsy surgery programmes. The majority of epilepsy centres no longer conduct a Wada test on every surgical candidate. The lateralization of language via invasive methods may not be necessary for temporal lobe epilepsy patients in whom a tailored resection will spare areas associated with language function. Functional MRI is being used in some centres to lateralize and localize language function in epilepsy surgery candidates. Magnetoencephalography also shows promise in this regard. Patients at high risk of a postoperative memory decline can be identified via multivariate models that utilize noninvasive measures of cerebral function and structure, together with demographic and clinical variables.

The clinical indications for a Wada test should be determined on a case-by-case basis, with careful consideration of the available noninvasive alternatives, to ensure that the risk–benefit ratio is appropriate for every patient.