Nerve signal–blocking device studied as an alternative to bariatric surgery

Follow-up trials needed to determine if this is a viable weight-loss option.

A new implantable device is being touted as a promising, less extreme alternative to bariatric surgery: vagal blocking therapy.

The newly published results of a six-month, open-label trial of 31 morbidly obese participants (BMI >35) indicated that those participants implanted with the vagal blocking therapy device lost an average of 15% excess weight. One-quarter of the participants lost greater than 25% excess weight, and three participants lost greater than 30%, according to a press release. The study was published in Surgery and was presented at the 25th Annual Meeting of the American Society for Metabolic and Bariatric Surgery, held recently in Washington, D.C.

Michael Camilleri, MD, gastroenterologist at the Mayo Clinic, Rochester, Minn, said that intermittent blocking of the vagal nerves was associated with significant excess weight loss and a desirable safety profile. Vagal blocking therapy is delivered through laparoscopically implanted leads that stimulate electrical impulses to block vagal nerve trunks. Patients can flip a switch on a subcutaneous neuroregulator to activate the device and influence how the stomach digests food, according to EnteroMedics, which funded the research.

Over six months, mean excess weight loss was 7.5% at four weeks, 11.6% at 12 weeks and 14.2% at six months (P<.001). Caloric intake decreased by greater than 30%; participants experienced earlier satiation, reduced hunger and suppressed plasma pancreatic polypeptide responses. Three participants had severe adverse events that required hospitalization for lower respiratory tract problems, subcutaneous implant site seroma and diarrhea.

Tantalus (Metacure) is a similar laparoscopically implanted device approved for sale in Europe that applies electrical stimulation to the stomach during food intake. According to results of another study published in Obesity Surgery, 20-week data in 12 obese patients showed reductions in hunger and body weight (17.6%), and one-year data (n=9) revealed even greater reductions in body weight (26.6%) and BP.

Data on vagal blocking therapy “are promising, but the next study will tell us whether VBLOC therapy is a viable alternative to gastric bypass or gastric banding and for which patients,” Camilleri said in a press release. A follow-up, double blind, “sham” study involving 300 patients at multiple centers is underway.

In contrast to bariatric procedures, vagal blocking therapy can be removed. Animal data have revealed no permanent damage to the vagal nerves. Vagal blocking therapy is not currently available or approved for use in the United States. – by Katie Kalvaitis

Obes Surg. 2006;16:627-634.

Surgery. 2008;143:723-731.

This is potentially interesting but highly preliminary. There are approved similar devices in Europe. The principal problem here is the lack of a control group. The weight loss reported is potentially the result of study intervention and the procedure itself, not the device. A blinded study is necessary to evaluate the device.

– Alan J. Garber, MD, PhD

Endocrine Today Chief Medical Editor