The case report by Loddenkemper et al¹ is most important as it poses the question of whether unilateral Wada testing is sufficient for language lateralisation. It is certainly possible that similar complications resulting from epilepsy surgery based on Wada tests are underreported. The implications of erroneous language lateralisation by unilateral amobarbital injection, which is increasingly used in several epilepsy centres including our own, would be far reaching.

There are, however, some caveats regarding the interpretation of the Wada test results reported. The first two refer to the assessment of cortical inactivation in this patient with pre-existing damage to the motor cortex; the third refers to the extent of brain areas inactivated by the intracarotid Wada procedure.

(1) Little is known about the relative susceptibility to the effect of amobarbital of language areas compared with damaged motor cortex. Thus it may be that a low dose of amytal (which 100 mg is) does impair a partially damaged motor cortex when language areas still maintain sufficient function to solve the tasks tested during the Wada procedure. In our experience, higher doses (140 to 200 mg) are often needed in adults to induce a complete contralateral hemiplegia. In order to avoid a possible risk of incomplete inactivation of the middle cerebral artery (MCA) territory and of language areas in particular, it may be advantageous to choose higher injection dosages.

(2) There is a striking discrepancy between well preserved proximal arm power (4-/5) after hemispherectomy as compared with …