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, it is not commercially available any more in Japan. In addition, there was a shortage of amobarbital supply on a world basis around 2003, due to ownership rights [1]. Initial comparison study of Wada test with propofol against amobarbital has already been reported [2, 3]. Informed consent was obtained from all the patients, according to the Clinical Research Protocol No. 358 approved by the Committee of Medical Ethics, Kyoto University. In this study, we retrospectively examined the following series of cases who underwent bilateral Wada test with propofol in our institute. 1. Grote, C.L. and K. Meador, Neurology, 2005. 65(11): p. 1692-3. 2. Mikuni, N., et al., Neurology, 2005. 65(11): p. 1813-6. 3. Takayama, M., et al., Neurology, 2004. 63(3): p. 510-5.Methods: As for practical procedures, diluted solution of 10mg 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. If the bilateral language impairment was observed, time difference > 30 seconds for first verbal/non-verbal response was regarded as relatively unilateral language dominance. Memory function was evaluated quantitatively through the 14 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. Functional evaluation was regarded as inconclusive in case of poor memory score in pre-Wada test and/or unstable condition of the patient.Results: 352 patients (209 male), who underwent bilateral Wada test between 2005 and 2015, were enrolled in this study. They are 312 right-handed, 30 left-handed, and 10 ambidextrous. The number of patients with definite language dominance as left and right was 255 and 14, respectively. The evaluation of language function was inconclusive in 21 cases (5.9%). The remaining 62 cases (17.6%) 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 117 and 16, respectively. The evaluation of memory function was inconclusive in 41 cases (11.6%). The remaining 178 cases (50.6%) resulted in bilaterally dominant to varying degrees. There was no major complication, which leads to permanent deficit.Conclusions: Wada test with propofol was indicated clinically useful enough, especially for preoperative evaluation of language function. On the contrary, memory evaluation tended to show bilateral dominance or became inconclusive. With intra- and/or inter-individual variations of cerebral circulation taken into account, the optimal task and protocol of Wada test need to be further refined in terms of memory function.