Abstracts

Rationale: The Wada test (intracarotid amobarbital procedure) has been used as a standard method for assessment of the risk of postoperative amnesia and milder forms of memory change following epilepsy surgery (Baxendale and Duncan, 2008). Shortages of amobarbital have caused some epilepsy surgery centers to use alternative anesthetic agents (Grote and Meador, 2005). In this study, we report our experience in Wada testing using three different drugs: amobarbital, brevital and etomidate. Methods: 136 temporal lobe epilepsy surgery candidates underwent Wada testing: amobarbital was used in the first 94 patients, brevital was used in the next 36 patients and etomidate was used in the last 6 patients. Results of the Wada memory scores were analyzed and compared, as well as differences in neurological status during the action of the drugs. Multiple regression analysis with backward elimination was performed, with memory asymmetry score being a dependent variable. Results: After adjusting for other variables, drug was found to be the most significant factor explaining the level of memory asymmetry (p<0.0001). The brevital mean memory asymmetry score (29.28%) was significantly smaller, compared to amytal (49.75%) and etomidate (62.5%) scores. Conclusions: Significant differences in memory asymmetry scores may reflect differences in the length of anesthetization during stimuli presentation. Variability in the test results raises the question of validity of the Wada memory test and its predictive value. The findings of this study call for a standardization of the procedure, particularly in light of current tendencies towards a noninvasive approach in prediction of postoperative memory risk.