The Wada test

In 1949, Juhn Wada described the use of the intracarotid amobarbital procedure (i.e., Wada test) to determine cerebral language dominance.1 The procedure was later modified at the Montreal Neurological Institute to also assess hemispheric memory,2 and has become a standard component of presurgical evaluation for epilepsy surgery. The Wada memory test is used to evaluate the risk of postoperative amnesia, to assess the risk of material specific memory deficits, to lateralize hemispheric dysfunction, and to predict postoperative seizure outcome. Four articles in the current issue of Neurology address controversies and important concerns regarding the Wada test.3-6 At times, agitation or obtundation during the Wada test make determination of language dominance problematic. To circumvent this limitation, Rihs et al. employ functional transcranial Doppler sonography (fTCD) to assess simultaneous differential left/right changes in middle cerebral artery blood flow to language and visuospatial tasks.3 Language lateralization via fTCD and the Wada test were highly correlated, suggesting that fTCD may offer a noninvasive alternative to the Wada test. Similar findings have recently been demonstrated for functional MRI (fMRI); fTCD is less expensive …