Abstracts

Rationale: Wada test has been widely used to determine the dominant hemisphere in terms of speech and memory function. While amobarbital has been commonly used for this purpose, there was a shortage of amobarbital supply on a world basis around 2003, due to ownership rights. Even though several drugs have been tried and reported in Wada test, any one of these drugs has not yet been established as replacement for amobarbital. In order to confirm clinical safety and practical usefulness, we applied propofol for this purpose in our institute. Methods: We checked PubMed database to find out any clinical reports of sedative drugs used for Wada test instead of amobarbital. As for practical procedures, diluted solution of 10 mg propofol as 1 mg/mL was used on one side, with additional injection as much as provoking contralateral hemiplegia up to the maximal dose of 15 mg. Language function was evaluated by symptoms of language impairment and onset time of the first verbal/non-verbal response after injection. Memory function was evaluated quantitatively through the 10 items, presented serially one minute after injection of propofol. The dominant hemisphere for memory was determined if the difference in the number of correctly recalled items was more than 5. Results: We finally found 75 clinical articles of Wada test without amobarbital. Propofol, Methohexital, Etomidate, Pentobarbital, and Thiamylal were actually used in 37, 22, 8, 5, 3 articles. 10 patients (6 male), who underwent bilateral Wada test between 2016 and 2018, were enrolled in this study. The etiology of each patient are 7 tumor, 2 cerebrovascular disease, and one epilepsy case. Number of patients with definite language dominance as left and right was 8 and 1, respectively. The remaining case resulted in bilaterally functional hemispheres to varying degrees. In contrary to this, the number of patients with definite memory dominance as left and right was 3 and 0, respectively. The evaluation of memory function was inconclusive in one case. The remaining case resulted in bilaterally dominant to varying degrees. There was no major complication, which leads to permanent deficits. Only 12% of centers continued a Wada test in 20081), while 85% of centers always performed in 1993. There has been an abrupt switch in role of Wada test, with coincidence of the worldwide shortage of sodium amytal. Curot et al. reported that the hemispheric dominance was determined in 72.4 % (propofol) and 77.7 % (amobarbital) for memory, while 96.5 % (propofol) and 94.4 % (amobarbital) for language. Several studies used wide variety of sedative agents instead of amobarbital. Most recent comparative study reported that propofol produced similar lateralization rates as amobarbital for both language and memory. In terms of safety, there were no differences found in average rate or severity of adverse effects (McCleary, 2018). Conclusions: Wada test with propofol was indicated clinically safe and useful enough, especially for preoperative evaluation of language function. The optimal task and protocol of Wada test need to be further refined, especially for memory function. Funding: We have no COI disclosure related with this abstract.