Freezing Hunger-Signaling Nerve May Spur Weight Loss

Pam Harrison

March 21, 2018

Freezing the posterior vagal trunk nerve using a minimally invasive, percutaneous technique significantly reduces appetite and results in substantial weight loss at 90 days, a small pilot study suggests.

"We wanted to address the phenomenon of diet attrition, as it is well known that 95% of patients who embark on their own weight loss attempts end up quitting," J David Prologo, MD, assistant professor of radiology and imaging studies, Emory University School of Medicine, Atlanta, Georgia, told the press during a webinar preceding presentation of the results on March 21 at the Society of International Radiology (SIR) 2018 annual scientific meeting in Los Angeles, California.

"In addition to cutting off the hunger signal from an empty stomach to the brain, freezing this hunger nerve also slows down the transit of food through the stomach so patients who have had this procedure get full faster and feel hungry less often," he added.

"So by using these 2 effects, we are making diets easier for patients — that's the goal and that's what we are seeing," Prologo observed.

So far 10 patients have undergone percutaneous CT-guided cryoablation of the posterior vagal trunk along the distal esophagus on the right, although more have subsequently been enrolled in the study.

Patients had a body mass index (BMI) of 30 to 37 kg/m2, "above normal but below the threshold for gastric bypass surgery and other bariatric interventions," Prologo noted.

For the first 90 days following the procedure, all patients reported having a decreased appetite. Over half the group reported that they had "very much less appetite" compared with baseline.

Moreover, excess BMI loss, as well as total weight loss, were comparable with other successful weight loss interventions followed over the same trajectory, as Prologo pointed out.

Endpoint Day 7 Day 45 Day 90
Average excess BMI lost, % 4.5 9.7 12.9
Average total weight loss, % 1.1 2.5 3.6
Patients reporting decreased appetite, % 100 100 100

There were no procedure-related complications or adverse events during follow-up.

Asked how long the freezing effect might last by Medscape Medical News, Prologo noted that when interventional radiologists freeze nerves in the periphery, usually to treat pain, nerves grow back at a rate of about 1 mm/day.

"So it would take about 12 months to regenerate from the distance of our cryoablation back to the connection in the brain," he elaborated.

The advantage of interventional radiology, which is illustrated particularly well with this procedure, is that the intervention can be done quickly and patients don't usually require substantial amounts of radiation.

"Patients come in the morning, we give them moderate sedation, and we numb the area through which we advance a needle probe about the size of a pen tip," Prologo explained.

The operator then freezes the target area for about 2 minutes, and the whole procedure takes about 35 minutes to complete.

"We simply put a Band-Aid over the puncture site and send the patient home an hour or 2 later," Prologo emphasized.

Millions Affected by Obesity: Better Weight Loss Methods Needed

Commenting on the need to find better ways to treat obesity, SIR president Suresh Vedantham, MD, professor of radiology and surgery, Washington University School of Medicine in St Louis, Missouri, reminded the press that obesity affects millions of people around the world, especially in the United States, and leads to a number of secondary conditions, "so it has a huge impact on our healthcare system and patients' lives," he noted.

Indeed, obesity has been a major area of interest to the SIR, he noted.

For example, another procedure, bariatric embolization, is also being used to treat obesity. Bariatric embolization blocks blood flow to the stomach using a minimally invasive procedure.  

"This is done to affect the secretion of hormones from the stomach that may trigger hunger," Vedantham explained, "so that's another mechanism we are looking at to try and help the medical community stem the tide of obesity."

Prologo reports receiving a research grant from Galil Medical, HealthTronics, and Cook Medical, and has served as a consultant to Galil Medical and Merit Medical. Vedantham reports receiving a research grant from Cook Medical.

SIR 2018 annual scientific meeting. Presented March 21, 2018. Abstract 2186.  

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