Who needs a Wada test? Present clinical indications for amobarbital procedures

The Wada test has been the gold standard for testing cerebral language localisation during presurgical investigation in the past decades. However, during the last few years a shift has occurred in epilepsy surgery programmes towards the use of non-invasive methods, predominantly functional MRI (fMRI). However, Wada tests are still performed, albeit in a considerably smaller number of patients at many epilepsy centres.

A retrospective monocentric analysis of remaining clinical indications for performing a Wada procedure was undertaken. The clinical data of patients who participated in Wada tests (42 hemispheric and 8 superselective procedures) during recent years were retrospectively evaluated.

Reasons for conducting a Wada test were (1) a patient's inability to perform the fMRI task due to agitation, mental disablement, or perceptual impairment, (2) validation of atypical, inconclusive or not clearly lateralised language activation shown with fMRI, (3) evaluation of propagation of ongoing interictal bilateral epileptiform EEG activity, (4) region selective testing of language and other cognitive functions, or (5) assessment of motor localisation. Patients who were not able to perform the fMRI task or in whom fMRI did not provide interpretable results were significantly younger (p<0.05).

It is argued that fMRI is eligible to replace Wada tests in the majority of patients who are compliant with clearly lateralised language localisation, but in patients who are agitated or mentally impaired as well as in the case of the above-mentioned specific clinical indications and bilateral fMRI activations, Wada tests still provide additional information. Additionally, non-invasive methods less sensitive to movement artefacts are discussed as possible alternatives for these patients.