Abstracts

Rationale: In animal studies, vagotomy leads to diminished satiety, while stimulation of the vagus nerve has the opposite effect with consequent decreased weight in canine and rat models. Therefore, the vagus nerve is thought to play a role in mediating hunger. The effects of vagus nerve stimulation (VNS) on weight in individuals being treated for epilepsy have yet to be fully characterized. Prior studies have examined changes in weight for patients with VNS as opposed to the more informative measure of body mass index (BMI) percentile. Methods: We performed an IRB-approved, retrospective, observational, cohort study on pediatric patients that underwent VNS placement at Duke University Medical Center from 2001 to 2009. The following were obtained prior to surgery and at follow-up visits: age, gender, weight, height, and seizure type. In addition, the number of anti-epileptic drugs (AEDs) which reduce and increase weight were recorded at baseline and last follow-up appointment. Baseline BMI percentile was compared to percentile on follow-up visits using a paired sample t-test. Bivariate analysis was performed to find variables that were significantly associated with change in BMI percentile at follow-up. Results: We studied 23 patients who had undergone VNS placement. Baseline BMI percentile was 61.7 34.3 (n=23). At one year follow-up (mean 345 112 days), and last follow-up (mean 4.2 2.4 years) the average BMI percentile was 61.6 31.88 (n=20) and 56.09 30.83 (n=23), respectively. There was no significant difference in BMI percentile as compared to baseline at 1 year and at last follow-up visit (p= 0.992 and 0.681, respectively). On bivariate analysis, change in BMI percentile was negatively correlated with the BMI at baseline (p=0.035), but had no correlation with age, gender, number of days to last follow-up visit, number of AEDs which reduce weight at baseline and follow-up, number of AEDs that increase weight at baseline and follow-up, and seizure type (p?0.058 for all). Conclusions: Long term pediatric VNS therapy does not have clinically significant effects on BMI percentile during follow-up for up to an average of over four years.