Vagus nerve stimulation does not lead to significant changes in body weight in patients with epilepsy

Vagus nerve stimulation (VNS) is an FDA-approved treatment for medically intractable epilepsy. The effect of this therapy on body weight is unclear. VNS could cause weight loss by engaging vagal afferents from the gastrointestinal tract mediating satiety.

We performed a retrospective analysis of body weight changes over a period up to 2 years following VNS implantation. We studied 21 patients (13 M/8 F) 35 +/- 12 years old, who received a Cyberonics VNS Therapy System for medically intractable epilepsy between April 1998 and May 2004. The mean +/- SD duration of follow-up was 613.1 +/- 389.1 days. The study had 80% power with a type I error of 0.05 to detect a 5% weight change. Data were analyzed with repeated-measures ANOVA.

Weight changes relative to baseline at 30, 60, 120, 360, 480, and 720 days were -0.17 +/- 2.33, +0.33 +/- 2.64, -0.32 +/- 3.56, +1.09 +/- 5.97, +1.06 +/- 7.47, and +0.33 +/- 3.69%, respectively. At all time points these differences failed to reach statistical significance.

Vagus nerve stimulation with parameters typically used in the treatment of patients with epilepsy was not associated with clinically significant weight changes. A well-controlled prospective study is necessary for more precise evaluation of the effect of VNS therapy on body weight.