Research Highlights: Temporary Blocking of the Intra-Abdominal Vagal Nerve Not Effective Enough to Replace Bariatric Surgery as a Treatment for Obesity

Temporary Blocking of the Intra-Abdominal Vagal Nerve Not Effective Enough to Replace Bariatric Surgery as a Treatment for Obesity

Bariatric surgery is a common treatment for weight loss in obese patients, but it can carry significant risks such as increased morbidity and an unappealing distortion of the body. Researchers have been investigating the efficacy of reversibly blocking the vagal nerve as a possible alternative treatment, as this treatment would be less invasive and come with fewer risks than bariatric surgery. The intra-abdominal vagal nerve controls metabolism, GI tract function and feelings of hunger. Previous studies have shown that temporarily blocking this nerve can result in substantial weight loss, but the results have only been significant in patients who had received the treatment for at least 12 hours a day.
239 people from Australia and the United States participated in this study. Participants were eligible if they could be classified as obese by their BMI and if they had an obesity-linked condition such as hypertension, type II diabetes, or sleep apnea. Researchers used an implanted device to block the vagal nerve. Two thirds of participants received an active device while the remaining third had a sham device implanted in order to act as a control group. For the experimental group, devices blocked the vagal nerve for 12 hours daily over a period of one year with occasional follow-up visits to monitor experiment progress and patient safety. For the sake of consistency within results, researchers did not encourage or prescribe any diet or exercise regimen for the participants.
Overall, 24.4% of participants with active devices lost excess weight while only 15.9% of sham participants (the control group) lost excess weight, a statistically significant result. Despite this difference, the weight lost by experimental participants did not meet the weight loss objectives set by the researchers to measure treatment efficacy. Researchers had hoped for at least a 10% difference between treatments, but results showed only an 8.5% difference. Therefore, blockage of the vagal nerve, while shown to result in some patient weight loss, was not deemed effective enough to be a treatment option under these experimental circumstances. 

JAMA. 2014; 312(9): 915-922


Caroline Russell-Troutman is the 2014-2015 Research Highlights Editor