Abnormal Wada and Neuropsychological Testing Results Due to Topiramate Therapy

Abstract

Summary:A 46-year-old man experienced intractable seizures since childhood. Due to lack of response to antiepilepsy drugs (AEDs), he underwent a surgical evaluation that was consistent with seizure onset in the left medial temporal lobe. While on topiramate and carbamazepine, his preoperative neuropsychological scores and sodium amytal (Wada) scores were low and may have excluded him from surgery. Repeat testing on lamotrigine and carbamazepine showed improvement in his scores, allowing him to undergo surgery. Physicians must therefore be cautious in evaluating such test scores while a patient is on topiramate. Key Words: Topiramate-WddaNeuropsychological-Surgery-Temporal.Although topiramate (TPM) is a potent antiepilepsy drug, cognitive side effects must be considered when choosing this new antiepilepsy drug. One particular concern would be if the drug interfered with the accuracy of neuropsychological testing, particularly in the case of surgical evaluation. We present a case where topiramate therapy caused significantly altered memory scores during standardized neuropsychological testing and in memory assessment during intracarotid sodium amytal (Wada) procedure. CASE REPORTR.K. is a 46-year-old right-handed male with a history of epilepsy since childhood, including febrile seizures. He is a college graduate with a degree in architectural engineering and serves as the manager of design/ construction at a major hospital. His seizures consist of staring, loss of awareness, and mild oral automatisms. They last from 30 to 45 s. He averaged 10-15 seizures per month. On at least one occasion, he was admitted Accepted March 10, 2000. Address correspondence and reprint requests to Dr. P. McCabe at Section of Neurology, Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA 17033, U.S.A. E-mail: pmccabe@psghs.edu with nonconvulsive status. Past medical management consisted of phenobarbital, mephobarbital, primidone, valproic acid, phenytoin, lamotrigine, and carbamazepine. Due to the intractability of his seizures, he underwent surgical evaluation. At the time, he was on carbamazepine (1,800 mg of extended releaselday) and topiramate (500 nig/day). While on this combination, his performance at work decreased, and he required a temporary leave of absence. He complained of decreased memory and concentration. Magnetic resonance imaging revealed left mesial temporal sclerosis and interictal electroencephalogram (EEG) showed frequent left-sided spikes with phase reversal at F7-T3 (ictal EEG was not obtained). R.K. then underwent neuropsychological testing andWada testing to complete his surgical evaluation. WMS-R general memory index was 66 (1st percentile), with verbal memory being 61 (<lst percentile) and visual memory being 97 (42nd percentile). Attention/ Concentration index was 99 (47th percentile), and delayed memory was 80 (9th percentile). Difficulties were also evident in verbal associative fluency and executive function tasks. Wada testing consisted of showing 8 items (3 objects, 2 words, 2 designs, ...

Language Disturbances as Side Effects of Topiramate and Zonisamide Therapy

“…A patient taking TPM and CBZ during a presurgical evaluation had scores so low on neuropsychological testing and a WADA test as to exclude him for consideration for surgical therapy, according to the authors (14). His scores improved when TPM was discontinued and he was maintained on LTG and CBZ.…”

Reduced Anesthetization during the Intracarotid Amobarbital (Wada) Test in Patients Taking Carbonic Anhydrase–Inhibiting Medications

“…The apparent drugdrug interactions may last for weeks after the last dose of CAI medication. In addition to the potential for reduced anesthetization during the IAP, these drugs also may affect neuropsychological and IAP memory scores (11,(23)(24)(25)29,30). Because the IAP is not without risk, everything should be done to ensure the most reliable results with the first test.…”

“…A recent report described an IAP memory examination failure in a patient taking TPM who had later passed the examination after TPM was discontinued (11). To explore whether the IAP memory examinations at our institution had been similarly affected by TPM, we compared memory performance among three groups of patients: the no-CAI group, the CAI group, and a separate group for those taking TPM.…”

“…One case study reported a memory failure during the IAP in a patient taking TPM who later passed the IAP when off the drug (11). A retrospective study on a small group of patients demonstrated that after ipsilateral injection, TPM patients had significantly lower percentage memory scores compared with non-TPM patients (30).…”

“…Because the amount of time that elapsed between the last TPM dose and the date of the IAP varied from 0 to 16 weeks, we were able to estimate the length of time off TPM required to obtain adequate anesthetization during the IAP. Last, we compared the IAP memory performance of patients taking TPM and other CAIs with that of patients taking other drugs to verify the prior case report of McCabe et al (11) describing reduced IAP memory performance due to TPM therapy.…”