Vagus Nerve Stimulation Duty Cycles of Pediatric Patients: Distribution over 12 Months.
Abstract number :
2.218
Submission category :
Year :
2001
Submission ID :
2319
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
J.R. Flamini, MD, Child Neurology Associates, PC, Children[ssquote]s Hospital of Atlanta, Atlanta, GA
RATIONALE: Vagus nerve stimulation, a treatment with proven efficacy in reducing the frequency of seizures, can be delivered at a variety of duty cycles (DCs). Most physicians begin VNS therapy at the slower cycles and ramp up to higher cycles as the patient[scquote]s tolerance for the therapy increases. However, little information is available regarding optimal duty cycles. The goal of this study was to identify the DCs that produced seizure reduction equal to or greater than the median seizure reduction of all patients at 3 and 12 months.
METHODS: We queried the VNS patient outcome registry for a constant cohort of patients younger than 18 years and with DC and seizure frequency data available at baseline and 3- and 12-month follow-up. We stratified DC data into six levels: [lt]10%, 10% through 19%, 20% through 29%, 30% through 39%, 40 through 49%, and [gt]=50%, and noted the number and percentage of patients with DCs in each category at each time point. We computed the median seizure reductions of the respective DC categories and compared them with the median seizure reductions of all patients in the constant cohort at both follow-up time points.
RESULTS: The constant cohort comprised 338 patients.[table]Median seizure reductions for the entire constant cohort were 50% after 3 months of VNS therapy and 62.5% after 12 months. With the exception of the [gt]=50% category at 12 months, all categories with 20 or more patients equaled or surpassed the median seizure reduction of the constant cohort at both time points.
CONCLUSIONS: These data show that most physicians begin VNS at slower DCs and move to more rapid DCs over time. Although median seizure reductions at more rapid DCs ([gt]=50%) were not as large as those at slower cycles ([lt]=49%), increased seizure reduction seems to be associated with the duration of the VNS (3 versus 12 months) rather than DC. Nevertheless, these findings do not preclude the possibility that adjusting DC could influence the response of an individual patient.
Support: Cyberonics, Inc.
Disclosure: Honoraria - Speakers[ssquote] Bureau