Abstracts

A recent report (Bookheimer, et al. 2005) suggested that patients taking carbonic anhydrase inhibiting drugs have an increased rate of anesthesia failures during the Intracarotid Amobarbital Procedure (IAP). This study aims to clarify the interaction between the carbonic anhydrase inhibiting drugs topiramate (TPM) and zonisamide (ZNS), and sodium amobarbital during the IAP in pediatric patients. A retrospective chart review was performed on pediatric patients with intractable epilepsy who underwent the IAP between 2002 and the present at the Minnesota Epilepsy Group. Fifteen patients were identified who were taking TPM or ZNS at the time of the IAP and 20 were identified who were on other anticonvulsants at the time of the procedure. Independent samples t-tests were conducted to determine whether the groups differed with respect to amobarbital dose, time to first motor return, and time to first verbalization. The two groups did not differ with respect to age (mean age = 13.07 for TPM/ZNS patients and 12.15 for patients taking other drugs), IQ (mean IQ = 81.5 for TPM/ZNS patients and 87.8 for patients taking other drugs), or total number of AEDs (mean number of AEDs = 2.5 for TPM/ZNS patients and 2.1 for patients taking other drugs). Patients taking TPM or ZNS were up to 10 times more likely to require an additional bolus of amobarbital to achieve sufficient motor loss and required a statistically significantly higher total dose of amobarbital to achieve complete anesthetization for both left (p[lt]0.02) and right (p[lt]0.01) injections than patients taking other AEDs. Six patients (40%) taking TPM or ZNS did not achieve complete motor loss despite additional Amytal, while only one patient (5%) taking other AEDs experienced anesthesia failure. Following left injection, patients taking TPM or ZNS experienced a significantly shorter recovery time for both motor (p[lt]0.01) and verbal (p=0.04) functions. For the right injection, the differences on these variables did not reach statistical significance. Language lateralization and hemispheric memory capacity findings were similar between the two groups. These results suggest reduced anesthesia effect of sodium amobarbital during the IAP in pediatric patients taking TPM or ZNS. Pediatric patients taking these drugs were more likely to require an additional bolus of amobarbital, received a greater total dose of amobarbital, were more likely to experience anesthesia failure despite the increased dose, and had shorter recovery times for both motor and verbal functions. While language and memory findings were similar between the two groups in this study, additional research is necessary to clarify the effect of reduced anesthesia on interpretation of language and memory performance during the IAP.