Abstracts

The vagus nerve stimulator (VNS) has been FDA approved for adjunctive use in refractory partial epilepsy in patients [gt]12-years-old. Post-approval experience has included patients with broader epileptic syndromes, ages [amp] general levels of function. Guardians [amp] caregivers of mentally retarded (MR) patients have hesitated to utilize VNS fearing increased complications [amp] less successful outcomes. We determined to evaluate our 8-year experience with the VNS in patients with refractory epilepsy, comparing patients with normal IQs [amp] those with MR for efficacy [amp] safety. A retrospective chart review was conducted of all patients with VNS implants with at least 1-year follow-up at Minnespota Epilepsy Group since 1997. Also, patient/guardian input was solicited via a mail survey that included questions of their subjective experience of safety [amp] efficacy with the VNS. 257 charts were reviewed: 157 adults (A), 100 children (P), ages 2 to 66-years-old. Nine were deceased. IQ was [gt]75 in 75 patients [amp] [lt]75 in 138 (MR) [amp] unknown (U) in 54. Twenty-five were lost to recent follow-up. Seizure (SZ) freedom occurred in 6% A, 13% P. [gt]75% SZ reduction occurred in 22% A, 35% P. [gt]50% SZ reduction occurred in an additional 21% A [amp] 27% P. SZs were worse in 9% A, 10% P. MR-P did significantly better in efficacy thatn MR-A. Complications (CX) were mild to none in 75-87%; both MR-A and MR-P had fewer CXs than normal IQ patients. VNS was removed or turned off in 10% A [amp] 16% P. Duty cycles utilized were more often intermediate or rapid settings in the MR-P group.
151 (59%) returned surveys. 46% of the whole group were more alert: 63% of normal groups, 47% MR with MR-P doing less well than the other groups. VNS was helpful in 78% of normals, 67% of MR, less often in MR-P. The magnet helped 76% of normals, 64% of MR, but less so in MR-P Both MR-A [amp] MR-P do well with VNS. 79% P (100% MR-P) [amp] 62% A (20% MR-A) achieve 50% or greater seizure reduction. MR populations also received marked benefit in subjective alertness [amp] overall improvement. Additional benefits were reported from magnet use. CXs were mild in all groups. Neither age nor IQ status predicts response. Refractory epilepsy patients can be considered good candidates for successful treatment no matter what IQ status or age. Other associated indications of patient satisfaction and function will be reported. (Supported by a grant from Cyberonics, Inc.)