Abstracts

Rationale: Wada test has been widely used to determine the dominant hemisphere in terms of speech and memory function, since it was introduced in 1949. While, for this purpose, amobarbital has been commonly used, it has not been commercially available in Japan from 2001. We reported first comparison of Wada test performed with propofol against with amobarbital. In this study, we retrospectively examined the following cases which underwent the Wada test with propofol in our institute. Methods: Actual procedure of the Wada test has been written in detail elsewhere. In summary, diluted solution of 10mg propofol as 1 mg/mL was used in 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. Total 14 items with four sets were presented, one minute after injection of propofol. Memory function was tested, usually10 minutes after the injection, through free recall and recognition by multiple choice for each item. The dominant hemisphere for language was determined if any language impairment were observed immediately following drug injection. In case bilateral language impairment was observed, time difference > 30 seconds for first verbal/non-verbal response was regarded as relatively unilateral language dominance. The dominant hemisphere for memory was determined if the difference in the number of correctly recalled items was more than 5. If the difference was between 2 and 5, both hemispheres were judged relevant to memory function, although larger number suggests relatively dominant side. If the difference was less than 2, the memory function was present equally on both sides. Functional evaluation was regarded as inconclusive in case of poor memory score in pre-Wada test and/or unstable condition of the patient. Results: 242 patients (140 male), who underwent Wada test between 2005 and 2014, were enrolled in this study. They are 222 right handed, 16 left handed, and 4 ambidextrous. 47 out of 242 patients were candidates for epilepsy surgery, 167 had brain tumors, and the remaining 28 had cerebral vascular disease. The number of patients with definite language dominance as left and right was 178 and 9, respectively. The evaluation of language function was inconclusive in 14 cases (5.7%). The remaining 41 cases (16.9%) resulted in bilaterally functional hemispheres to varying degrees. On the other hand, the number of patients with definite memory dominance as left and right was 92 and 8, respectively. The evaluation of memory function was inconclusive in 30 cases (12.4%). The remaining 112 cases (46.2%) resulted in bilaterally functional hemispheres to varying degrees. Conclusions: The Wada test with propofol was indicated clinically useful enough, especially for preoperative language evaluation. On contrary to this, memory evaluation tended to be inconclusive or show bilateral dominance. The optimal task and/or protocol of the Wada test need to be further refined in terms of memory function.