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Biomedicine

A Stimulating Treatment for Sleep Apnea

An implant stimulates the tongue to treat the disorder.

Unlike most researchers, the engineers at ImThera Medical just might consider it a compliment if someone called their product a “snooze.” The experimental device is designed to treat sleep apnea, a breathing disorder that can disrupt sleep and trigger serious complications, including an increased risk for heart disease and stroke, as well as daytime sleepiness so severe that sufferers often fall asleep at the wheel. The implant, which wraps around a nerve connected to the tongue, is now being tested in a small clinical trial in Europe.

Breathe easy: A new implantable device to treat sleep apnea wraps around the tongue’s large hypoglossal nerve, stimulating it in six different places to keep the tongue muscle toned and less likely to fall back and obstruct a person’s airway as he sleeps. It’s powered by a small rechargeable generator and computer, about the size of a Zippo lighter, implanted in the patient’s chest.

Sleep apnea is one of the most common kinks to the breathing process. It affects as much as 4 percent of the U.S. population, and occurs when something–usually a blockage, such as the tongue–stops a person’s breathing multiple times throughout the night. The resulting oxygen deprivation and sleep loss leads to fatigue in the short-term, but it can also cause serious long-term health problems.

The gold standard for sleep apnea treatment is a CPAP (Continuous Positive Airway Pressure) machine, which keeps the airway open by forcing air through a mask and down a person’s throat. But the device is loud and uncomfortable, and roughly half of CPAP users can’t tolerate it. Alternative therapies include everything from a device that changes the relative positions of the upper and lower jaw, to actually breaking the jaw and repositioning it, to something as invasive as cutting out a portion of the patient’s soft palate to increase the airway opening.

ImThera’s device takes a different tack, one that hasn’t yet been broadly explored. The neurostimulator wraps around the tongue’s large hypoglossal nerve, and delivers electric pulses to the nerve in up to six different spots. “The goal is to open the airway by not allowing the tongue to collapse,” says Marcelo Lima, the company’s president. It does that by creating muscle tone in the muscles on the side of and beneath the tongue–muscles that flatten, stiffen, and pull the tongue forward, preventing it from relaxing and falling back to block the airway. Power comes from a rechargeable pulse generator, about the size of a Zippo lighter, which is implanted beneath the skin above the pectoral muscle in the chest, and is connected to the stimulator with a small power wire that snakes up to the throat.

Lima first tested the device using external power on two hospitalized patients in Brazil. The results were so promising that the refined device is already the center of a small clinical trial of 12 patients in Europe; a larger trial is scheduled to begin in the U.S. in mid-2010.

However, not everyone thinks that targeting the tongue will provide a broad solution, largely because the anatomical causes of sleep apnea are not well understood. The physical obstructions–while they include the tongue–can be elsewhere and difficult to pinpoint in individual patients. “There are 16 other muscles that are possible culprits in sleep apnea,” says Lisa Shives, medical director of Northshore Sleep Medicine in Evanston, IL. “And in general, we don’t know exactly where each person’s obstruction is.”

However, other sleep specialists are interested to see what the trials show, especially given the dire need for new treatments. “I think it’s an intriguing concept and worth exploring,” says Susan Sprau, a sleep expert at the University of California at Los Angeles. “I applaud the effort of this company to work on a new and somewhat out-of-the-box treatment approach, and we’ll have to wait and see whether or not it pans out.”

Compared to the CPAP machine, ImThera’s device has better odds of reaching 100 percent compliance–once the device has been implanted, if it works, there’s little left for the patient to do. “It’s always nice to have other alternatives out there,” says neurologist Alon Avidan, associate director of the Sleep Disorders Center at UCLA. “We always see patients who have failed everything. And short of putting a hole in their throat with a surgical tracheostomy, this is another alternative that may improve sleep apnea without compromising or adversely affecting the patient’s quality of life.”

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