For many years, gastric electrical stimulation (GES) has been under investigation as a treatment for obesity and overeating, but until last week, it has only been experimental. After 12 years, the FDA finally approved EnteroMedics device for treatment of obesity, making it the first “gastric pacemaker” to be approved for obesity treatment.
About the size of a pacemaker and implanted into the person’s abdomen, the EnteroMedics’ Maestro™ device is intended to offer potential weight loss for those struggling with obesity. Called VBLOC™ for vagal blocking therapy, its electrode touches the vagus nerve at a point between the esophagus and the stomach, and it works by intermittently down-regulating or blocking input from the stomach’s vagal nerve to part of the brain linked to appetite in people who have issues with obesity and metabolism.
Historically, the independent research of such devices has not been earth shattering. Both SBU (’04) and Buchwald (’02) felt that the results were not conclusive and that EGS did not provide satisfactory results. This discouraged them from carrying on with the study (Salvi ’09).
In a 2009 study, Shikora et al compared implantable gastric stimulation therapy to a standard diet and therapy regimen. Within their group of obese subjects, the team evaluated differences in weight loss and found that the control group lost 11.7% and the IGS group also lost 17.6% of excess body weight. The difference in results between the two groups was less than a high recommendation of the treatment.
In a more recent study, after 12 months with the EnteroMedics device, those with the device fitted lost an average of 24 per cent of their excess weight, while those in the control group without the device fitted lost only 16 per cent. The device produced an overall difference in total body weight of only 3% over the sham device, which did nothing (Ikamuddin’14). Therefore, though there was certainly clinically significant weight loss with this device, the procedure fell short of being as effective as the researchers had hoped.
Repeated evidenced-based failures to support the “stomach fullness theory” suggest seeking alternative signals to relay cessation of eating. This adds credibility to the idea that the primary feedback may be dictated by satisfaction rather than fullness. This suggests placing more emphasis on hedonic (pleasure) messages in research and potential therapy.
While this FDA approval may show some promise, who will it work for, what will it work with?
There are still several important under-researched questions to consider coming out of the trials to date:
- How useful is it to rely solely on stomach hunger and fullness to create eating cessation? (Ikamuddin’14)
- How will gastric stimulation stack up in more comprehensive comparisons to other treatments – such as diet, behavioral therapy, exercise? (Ikamuddin ’14; Dixon ’11).
- We should be looking at response systems other than fullness, such as hedonic (pleasure) messages, for which treatment would be entirely different, less invasive, and possibly more long-lasting.
- Cross-study between the medical mechanisms of obesity and the psychological/behavioral components is needed for optimum diagnoses – that is, which patients will benefit from which treatments – surgical, pharmaceutical, psychotherapeutic, and implant – or treatment combinations.
Buchwald H and Buchwald JN Evolution of operative procedures for the management of morbid obesity 1950-2000 Obes Surg (2002) 12: 705 – 717.
Salvi PF et al Gastric pacing to treat morbid obesity: Two years’ experience in four patients Ann Ital Chir (2009) 80: 25 – 28.
Shikora SA et al Implantable gastric stimulation for the treatment of clinically severe obesity: Results of the SHAPE trial Surg Obes Relat Dis (2009) 5: 31 – 37.
Swedish Council on Technology Assessment in Healthcare (SBU)n Gastric pacing (gastric electrical stimulation) for the treatment of obesity — early assessment briefs (Alert) Stockholm, Sweden: SBU (2004).
Yao S et al Retrograde gastric pacing reduces food intake and delays gastric emptying in humans: A potential therapy for obesity? Dig Dis Sci (2005) 50: 1569 – 1575.
Dixon JB et al Surgical approaches to the treatment of obesity Nature Reviews Gastroenterology and Hepatology (2011) : 429 – 437.
Ikamuddin S et al Effect of reversible intermittent intra-abdominal vagal nerve blockade on morbid obesity: the ReCharge randomized clinical trial JAMA (2014) 312: 915 – 922 [VBLOC-DM2 ENABLE Trial].