Functional location of the language cortical areas in focal refractory epilepsy using the conventional, selective, and supraselective Wada test

Abstract

In refractory focal epilepsy, resective surgery offers an alternative for seizure control. However, there is a risk of language deterioration when the epileptogenic zone involves an eloquent cortical region. The Wada test involves the insertion of a catheter through the internal carotid artery and the injection of a short-acting anesthetic, resulting in transient loss of hemisphere function. While its specificity is high, its sensitivity is reduced, despite its limited or absent spatial resolution. Additionally, the generalized action of the anesthetic may lead to misinterpretations due to global cognitive arrest, particularly in patients with baseline deficits. The aim of this report was to prove the refinement of the selective and supraselective protocols, as well as their contribution to overcoming these disadvantages. The procedure began by placing a microcatheter in progressively more distal irrigation sites, according to the required technique, gradually performing angiography with contrast medium. Tissue perfusion allowed the identification of the cerebral parenchyma where the anesthetic would act. After injection, the assessment of neurocognitive changes was conducted. The characterization of language patterns was performed, delineating indispensable eloquent zones and dispensable eloquent zones, irrespective of the patients’ cognitive condition. There was concordance between the findings and post-surgical results. The selective and supraselective Wada test surpasses the disadvantages of the conventional method and proves decisive in surgical planning and decision-making.