The effect of vagus nerve stimulation therapy on body mass index in children.

The effects of vagus nerve stimulation on weight in individuals with epilepsy are not fully characterized. A retrospective review was performed of all pediatric patients who underwent placement of a vagus nerve stimulator at Duke University Medical Center. Baseline body mass index (BMI) percentile was compared with percentile on follow-up visits. We studied 23 patients who had undergone VNS placement during the period 2001-2009. Baseline BMI percentile was 61.7 ± 34.3. We had a power of 81% to detect a difference of 20 in BMI percentile from baseline to last follow-up. At the 1-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 and 56.09 ± 30.83, respectively. There was no significant difference in BMI percentile as compared with baseline at the 1-year and last follow-up visits (P=0.992 and 0.681, respectively). Long-term pediatric VNS therapy did not have a major clinically significant effect on BMI percentile during an average follow-up of more than 4 years.