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 [1]. The situation is similar in Japan, as it is not commercially available any more. Initial comparative study of Wada test with propofol against amobarbital has already been reported [2, 3] in another institute. In order to confirm clinical safety and practical usefulness, we applied the same protocol the following series of cases who underwent bilateral Wada test with propofol in our institute. 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 the first verbal/non-verbal response was regarded as relatively unilateral language dominance. 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. Functional evaluation was regarded as inconclusive in case of poor memory score in pre-Wada test and/or unstable condition of the patient.  Results: 5 patients (4 male), who underwent bilateral Wada test between 2016 and 2017, were enrolled in this study. All of them are right-handed. The etiology of each patient are 4 tumor and 1 cerebrovascular disease cases. Number of patients with definite language dominance as left and right was 4 and 0, 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. In addition, with induction of prior steroid administration, we have no case who showed minor temporary complication, interfering the evaluation of test. 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. 1.       Grote, C.L. and K. Meador, Has amobarbital expired? Considering the future of the Wada. Neurology, 2005. 65(11): p. 1692-3.2.       Mikuni, N., et al., Evaluation of adverse effects in intracarotid propofol injection for Wada test. Neurology, 2005. 65(11): p. 1813-6.3.       Takayama, M., et al., Intracarotid propofol test for speech and memory dominance in man. Neurology, 2004. 63(3): p. 510-5. Funding: The authors declare no conflicts of interest associated with this manuscript.