Good Results for Less Invasive Obesity Surgery In Small Study
Tuesday, July 03, 2007
Vagotomy involves snipping vagus nerves at the bottom of the esophagus/top of the stomach.
An operation once popular for the treatment of ulcers may prove to be an overlooked weight-loss solution for the newly obese. The surgery, which removes part of the vagus nerve in the esophagus, resulted in
significant weight loss with few lasting side effects and same-day recovery, according to early data presented recently at a plenary session of the annual meeting of the American Society for Bariatric Surgery (ASBS) in San Diego. Researchers believe new high-tech versions of the procedure could offer a middle-of-the-road option to millions of obese patients who are not helped by drugs nor ready to undergo major surgery, and for whom the weight loss seen in the study would reduce their immediate risk for obesity-driven heart disease and diabetes.
In the 1980s, an older version of the study procedure, called truncal vagotomy, was found to reduce weight in patients that underwent the procedure to treat their ulcers (the same nerve pathway controls stomach acid). It never took off for weight loss, however, because surgery at the time was used only for the most severe cases, and the open-abdomen version used then was not that much less invasive then more efficacious bariatric surgeries just stepping into the limelight (e.g. gastric bypass). Obesity was not taken as seriously then, and vagotomy was set aside until recent technical innovations, and the fact that 15 million Americans are now morbidly obese, rekindled interest. In addition, surgery for weight loss has become more popular, with 10 times as many procedures performed in 2005 as in 1998.
Researchers at the University of Rochester Medical Center, and at the University of California at San Francisco, together enrolled 30 obese patients for the current study, the first to specifically examine the effectiveness of laparoscopic vagotomy for the treatment of obesity. By the time of the meeting, just 11 patients had completed a six-month post-surgery follow-up period, but early results were strong enough to be included in an ASBS plenary session titled “Emerging Medicine/Research.” The study found that 10 of the 11 patients responded to the procedure and that they lost an average of 18.4 percent (Range 7.0 to 44.1) of their excess body weight. These results are in line with the results of older, ulcer treatment studies, which found about 20 percent excess weight loss.
Current bariatric (weight-reducing) treatments include surgical procedures like “lap-band” and gastric bypass and drugs like sibutramine (Meridia) and orlistat (Xenical). A third, much-touted experimental drug, rimonabant (Acomplia), just failed to receive the recommendation of a U.S. Food and Drug Administration advisory panel because of reports that it increases suicidal thoughts. Even approved drugs, however, are meant for short-term treatment only and are of limited use to severely obese patients. Current surgical options, while bringing about higher percentage weight loss (30 to 50 percent in first six months), may involve implants that breakdown over time or require a month of painful recovery time.
“More treatment options are clearly needed as this epidemic continues to grow, options that can be mixed and matched for better effect,” said Thad J. Boss, M.D., assistant professor for General Surgery within the Department of Surgery at the Medical Center in Rochester, a surgeon within the Bariatric Surgery Center at Highland Hospital and a principal investigator for the study. “Our study confirms that laparoscopic vagotomy is a very quick, safe and effective treatment for obese patients, especially for those whose weight gain is just getting to the point where it’s driving other diseases.”
Joining Boss as authors from the Medical Center were Thadeus L. Trus, M.D., associate professor of Surgery within the Minimally Invasive Surgery Program, and Jeffrey H. Peters, M.D., Chair of the Department of Surgery. The lead author for the study, also published in the May-June edition of the ASBS journal Surgery for Obesity and Related Diseases, was Robert H. Lustig, M.D., professor of Clinical Pediatrics in the Division of Endocrinology at UCSF. Also leading the study from UCSF was Marco G. Patti, M.D., associate professor of Surgery in Residence. The work is based on an unrestricted grant from EndoVx Inc., a private medical device company developing a system with the goal of making outpatient vagotomy easier on patients.
The two vagus nerves that run from the brain stem along the esophagus and into the stomach play a central role in passing on the “hunger message.” During a vagotomy, the surgeon clips out a one-centimeter piece of each nerve, interrupting their ability to send messages. In the laparoscopic version of the surgery used in the current study, the surgeons made small incisions through which a viewing tube (laparoscope) and surgical tools were inserted to clip the nerves. It involves less pain, risk and scarring and faster recovery than open-abdomen surgery, Boss said. The next step will be to see whether the procedure can be done with no incision whatsoever by going down the esophagus to interrupt the vagus nerves with an ultrasound burst, the goal of the EndoVx system.
In the current study, vagotomy was performed on 26 female and four male obese patients with an average weight of 240 pounds, plus or minus 30 pounds, who were mostly in their early 40s. Women are more likely nationwide to seek out this form of surgery, despite recruiting efforts to get men interested. Patients had an average score of between 35 and 45 for Body Mass Index (BMI), a measure of adiposity (bodily fat content) that takes into account a person’s height. A BMI of 30 or more signals the onset of obesity.
In terms of side effects, past studies had shown that vagotomy was associated with gastoparesis, where food moves through the stomach so slowly that it causes belching, stomach upset, diarrhea, vomiting, etc. One of the key, current findings is that, while the procedure does cause decreased motility (the speed which food moves through the stomach), that can be a tremendous positive if patients combine the procedure with a low calorie diet. In a low-calorie scenario, decreased motility makes people feel full with less. Anecdotally, many patients report eating one-third less food due to this effect, Boss said.
In addition, the study results will also be used to confirm whether or not vagotomy alters neurochemical pathways related to appetite and the onset of diabetes. Hunger hormones like ghrelin, for example, and other compounds that control appetite converge on a key part of the brain, the arcuate nucleus. Connecting this appetite control center in the brain to the stomach are the vagus nerves clipped during vagotomy, offering a potential explanation for weight loss beyond changes in motility. Past studies also show that glucose tolerance, a measure of diabetes risk, on average reverted to normal after the procedure. Thus, the current study collected data to be analyzed in the coming months, not just on obesity markers like ghrelin, but also on diabetes-related markers like blood glucose and insulin.
Also to begin in Rochester, perhaps in six months, is a study where as many as 60 patients will undergo vagotomy to confirm its effects and to explore the benefits of combining it with lap-band surgery. One previous study found the combination to offer efficacy closer to gastric bypass, but with quicker recovery.
“Beyond learning more about the basic biochemical mechanisms that create hunger, we hope this line of work will help us to intervene earlier to keep patients from becoming obese in the first place, or to chose which patients will be most helped be each treatment option,” Peters said. “Furthermore, these surgery studies could help design better drugs, and perhaps further the understanding of diabetes.”
"It's very clear that the use of drugs to treat obesity is limited by their modest efficacy, while gastric bypass surgery is limited by its invasiveness and expense," Lustig said. "The procedure used in this study appears to demonstrate reasonable efficacy and safety in our pilot trial, as well as the potential to for greatly reduced expense over other common surgeries. However, further studies will be needed to determine who can most benefit from vagotomy."