Abstracts

RATIONALE: The Vagal Nerve Stimulator is an efficacious therapy that was approved in 1997 for intractable partial and secondarily generalized seizure disorders. Fifty-six patients have been newly implanted at our center since February 1998. Due to the high parameters that were set, the generators lasted an average of two to three years. the patients were then given the option at the end of service to have the device replaced.
METHODS: At our center we evaluated the VNS device at each office visit. We considered replacement when there was high lead impedance with a DC-DC code of 7 on the normal mode diagnostics or when the divice would not interrogate or showed high lead impedance on lead diagnostic testing. The decision for replacement was based on seizure reduction, seizure intensity, and efficacy of magnet.
RESULTS: 22 (78.5%) of 28 patients elected to have their stimulators replaced. 20 patients elected to have their device re-implanted due to end of service. Two patients were re-implanted because of lead dysfunction. 3 (14%) of the patients who were re-implanted reported an overall greater than 75% reduction in seizures and 5 (28%) of the patients had a greater than 50% reduction in the number of seizures reported. 9(40%) reported that the intensity of their seizures was lighter. 5(22%) of the patients reported that the magnet either decreased the intensity or aborted the episodes. Two patients reported that the post-ictal phase was not as intense. 4 (18%) of the patients had sufficient improvement to warrant re-implantation. One adolescent became more verbal.
CONCLUSIONS: 22 (78.5%) of 28 patients elected to have their stimulator re-implanted for various reasons including seizure reduction, lessening of seizure intensity, decreasing post-ictal phase and or/ magnet efficacy.
[Supported by: The comprehensive Epilepsy Care Center for Children and Adults St. Louis, Missouri]