WASHINGTON – Loud snoring may do more than irritate a spouse: It can signal sleep apnoea, depriving a person of enough sleep to trigger a car crash, even a heart attack.
Now scientists are beginning to test if an implanted pacemaker-like device might help certain sufferers, keeping their airways open by zapping the tongue during sleep.
One of the main causes of obstructive sleep apnoea is that the tongue and throat muscles relax too much during sleep, enough to temporarily collapse and block breathing for 30 seconds or so at a time. The person jerks awake and gasps, a cycle that can repeat itself 30 or more times an hour, depriving patients of crucial deep sleep.
The idea behind the experimental implant: Stimulate the nerve that controls the base of the tongue with a mild electrical current during sleep, and maybe it will stay toned and in place like it does during the day rather than becoming floppy.
By the end of January, Minneapolis-based Inspire Medical Systems plans to begin enrolling 100 apnoea patients in a key study in the US and Europe to see if so-called hypoglossal nerve stimulation really could work. Two competitors are developing similar implants: ImThera Medical of San Diego says it hopes to begin US studies later next year, and Apnex Medical of St.
Paul, Minnesota, has announced some small-scale testing.
“In this kind of research, we’re not looking for little changes,” says Dr Meir Kryger, a sleep medicine specialist at Gaylord Hospital in Connecticut, who is helping to lead Inspire’s study. “What we’re looking for is actually cure.”
With Inspire’s system, doctors implant a small pacemaker-like generator under the skin near the collarbone, and snake a wire up under the jaw to that tongue-controlling nerve. A sensor at the diaphragm detects when a patient takes a breath, signalling the implant to zap the nerve. Researchers adjust the power so that the nerve is stimulated just enough to keep the tongue from falling backward during sleep but not to stick out. Patients turn on the device at bedtime with a remote control, complete with a timer they can set so they fall asleep before the pulses begin.
“I don’t have any idea while I’m sleeping that it’s on,” says Krohn, the Minnesota man who’d given up on apnoea treatment until volunteering for an early Inspire study last year – and says he now gets a good night’s sleep. “It’s a game-changer for me.”
Obstructive sleep apnoea is particularly common in people who are overweight and in middle-aged men, but anyone can have it.
The condition stresses the body in ways that increase the risk of high blood pressure, heart attack, stroke and diabetes. More immediately, severe apnoea increases the chance of a car crash sevenfold.
Today’s most successful treatment, called CPAP, uses special bedtime masks to gently blow air through the nose to keep airways open. But studies suggest at least 30 percent of diagnosed apnoea patients won’t or can’t use CPAP. They cite masks that fit poorly and leak, or say they feel claustrophobic, or rip them off while tossing and turning during the night.
Surgeons sometimes try removing part of the roof of the mouth or other soft tissues to treat apnoea by widening airways. But it’s hard to predict when these difficult operations will help, so they’re usually reserved for the most severe cases.