Implanted Gastric Stimulation

Many weight loss surgeries are based on deception. The modus operandi of restrictive weight loss surgeries is to fool or trick the brain into thinking that the stomach is full. Some surgeries accomplish this by actually removing a large portion of the stomach while others go about their deceit through the formation of sleeves or by placing artificial bands around the stomach. The general principle is that if obese patients feel full, they will stop eating and if the sensation of fullness occurs after a small amount of food, patients will eat far less than they usually do and will, in turn, lose weight.

 

One device takes this deceit to a new level, by using the brains own language directly, electrical signals. There have been two major approaches that use electrical signals to influence the digestive system. The first approach was to disrupt gastric emptying. The idea in this approach is to delay food from leaving the stomach and moving into the duodenum so that patients will feel full longer. This approach has not been very effective.

The second approach is a bit more sophisticated. The current implanted gastric stimulation approach a involves the placement of a device, similar to a pacemaker, into the patient’s abdomen. The device sends tiny electrical signals into the belly’s nervous system (yes, the gastrointestinal tract has its own nervous system). The electrical signals are painless and do not seem to interfere with other systems of the body. The electrical stimulations travel up the vagus nerve, to the brain, and are apparently detected by the brain as a sensation of fullness.

One company, Medtronix, is pioneering this work and has recently finished Phase II clinical trials on a device called the Transcend II. Unfortunately, the most recent studies have not been very promising but makers of the device remain hopeful. Improvements may involve varying the intensity and frequency of signals that are delivered by the device.

A similar device has been used to treat patients that experience problems with stomach emptying, a consequence of certain diseases such as longstanding diabetes and Parkinson’s disease. In the case of gastric emptying, the electrical signals stimulate the stomach to contract and propel its contents into the duodenum (small intestine) and along the digestive tract.

Since the same company developed and markets the gastric stimulator for problems of stomach emptying it is hoped that information gleaned from that application will be successfully applied to weight loss. From a mechanistic perspective the approach makes sense. Since the brain uses tiny electrical impulses from nerves to detect when the stomach is full, once scientists determine how to precisely mimic these signals, they should be able to tell the brain “the stomach is full” when in actuality it is nearly empty. Thus implantable gastric stimulation will one day be able to “fool” the brain into thinking that the stomach is full.