Abstracts

Rationale: This study was designed to determine if there is good evidence that patients undergoing a Wada test before epilepsy surgery should not be taking topiramate at the time of the procedure. One method to document a valid Wada test is to time the duration of hemiparesis after intracarotid amobarbital. Bookheimer et al. reported in 10 cases and 46 controls, that topiramate and other carbonic anhydrase inhibitors reduce the duration of hemiparesis during the Wada test and recommended that patients be off the medication for 8 weeks before testing (Epilepsia, 46:236-243, 2005). We reviewed Wada tests in 462 intracarotid amobarbital injections and rated the duration of hemiparesis for comparison. Methods: Wada tests performed from 1997 to 2006 were included in this retrospective analysis. Medications during the test and duration of hemiplegia and hemiparesis were recorded with motor strength graded at baseline and during regular intervals while memory items were presented after 120 mg intracarotid amobarbital. 26 patients on topiramate had 60 intracarotid amobarbital injections. The control group of 190 patients was not taking topiramate or zonisamide; this group included 402 amobarbital injections. Results: In the topiramate group, in 51 intracarotid amobarbital injections, the recovery of hemiparesis from time of injection to 3/5 strength ranged from 0-713 seconds with a mean ± SD of 291 ± 155 seconds Recovery to 5/5 strength ranged from 0-1050 sec with a mean of 398 ± 176 seconds Patients not taking topiramate or zonisamide recovered 3/5 strength with a range of 0-2506 seconds with a mean ± SD of 334 ± 175. Recovery in this group to 5/5 strength had a range of 0-2577 seconds with a mean ± SD of 428 ± 183. Relevant statistical comparisons had p>0.05 using t-tests with two-sided P value. Conclusions: While nonsignificantly shorter weakness duration was noted in patients taking topiramate compared to patients not on topiramate or zonisamide, these data indicate a wide range of paresis duration during the Wada test independent of therapy and do not support the routine discontinuation of topiramate in presurgical epilepsy surgery candidates having a Wada test. We feel it is unnecessary to risk the adverse consequences of medication changes or delay presurgical testing when patients are medicated with topiramate.