Nov. 9, 2005 -- Sleep apnea can cause fatal strokes, a new study shows.
As many as one in four men and one in 10 women have obstructive sleep apnea -- abnormal breathing in which the throat closes over and over again during sleep. In its mild forms, it causes industrial-strength snoring. As it becomes more serious, a person finds it very hard to stay awake during the day.
Sleep apnea is linked to heart disease. It's also linked to stroke. But it's never been clear whether sleep apnea causes stroke or the other way around. Now it is, report Yale researcher H. Klar Yaggi, MD, MPH, director of the VA Connecticut sleep laboratory, and colleagues.
Yaggi's team looked at more than 1,000 people seeking medical help for nighttime breathing problems. Two-thirds of these age-50-or-older people turned out to have sleep apnea; some, but not all, chose to be treated.
"Those patients with obstructive sleep apnea had about a twofold increased risk of stroke or dying compared to those without sleep apnea," Yaggi tells WebMD. "Those with more severe obstructive sleep apnea had threefold risk of stroke or death from any cause -- and that was after adjusting for other stroke risk factors."
The findings appear in the Nov. 10 issue of The New England Journal of Medicine. So does a commentary by Virend K. Somers, MD, PhD, professor of medicine and consultant in cardiovascular disease at the Mayo Clinic in Rochester, Minn.
"This is the best data so far implicating sleep apnea as a probable cause of stroke," Somers tells WebMD.
Can Sleep Apnea Treatment Save Lives?
The Yaggi study was not designed to test the effects of treatment. But it raises questions about how well doctors treat patients with obstructive sleep apnea.
"The problem is these patients were being treated in different ways. And even though they were treated, their risk of stroke was very high," Somers says. "This could mean, gosh, if they weren't being treated, their risk of stroke would have been even higher. Or it could mean that treatment was not as good as it could be in preventing stroke."
Yaggi says there's a strong suggestion that treatment did help.
"We think perhaps the risk would have been even greater if those people had not gotten treated," he says. "But the design of our study was not such that we could draw any conclusions about the impact of therapy. That is the next study that needs to be done."
There's no argument that sleep apnea treatment can get quick results in treating many of the symptoms of obstructive sleep apnea. Treatment not only helps snoring and daytime drowsiness, but it also reduces the high blood pressure caused by sleep apnea, says David M. Rapoport, MD, director of the sleep medicine program at New York University. Rapoport was not involved in the Yaggi study.
"Maybe it takes a long time to accumulate the effects of treatment, and even though patients get better they may not eliminate the stroke risk right away," Rapoport tells WebMD. "There is a cumulative effect of sleep apnea. It is like smoking. If you smoke for 20 years and then stop, you are at higher risk of lung cancer for a while."
Treating Sleep Apnea
Treatment for obstructive sleep apnea gets better all the time, experts tell WebMD. Which treatment is best? That depends on the severity of the problem.
Many people with sleep apnea are obese. Sleep apnea can cause weight gain. The good news is that relatively little weight loss has a huge effect on improving sleep apnea.
"Obstructive sleep apnea tends to melt away with weight loss," Yaggi says. "If patients are able to maintain weight loss, the obstructive sleep apnea gets better or goes away. Just 10% to 20% weight reduction cuts in half the severity of obstructive sleep apnea. Just that much -- it's not necessary to drop down to one's ideal weight."
For people with mild sleep apnea, treatment might be as simple as sleeping on one's side. If that sounds like a problem, try sleeping in a T-shirt with a tennis ball sewn into the middle of the back.
Paradoxically, surgery helps only the milder forms of obstructive sleep apnea.
"If there is an abnormal structure of the upper airway, then you can make a case for surgery," Somers says. "Tracheostomy is what we do. There are other kinds of surgery where we cut through the uvula, that little structure at the back of the throat, and the upper airway. That seems to work for a short while. Unfortunately, it does not appear to be a definitive treatment -- and if you have surgery, you want it to be curative. The trouble is that in six months to a year the airway gets flabby and apnea comes back."
"It is the patients with mild-to-moderate sleep apnea who respond to surgery," Yaggi says. "Patients who are not obese tend to respond better."
Mouthpieces and Masks
Another treatment for milder forms of obstructive sleep apnea is an oral appliance. This mouthpiece-like device brings the lower jaw forward and opens space in the back of the throat during sleep.
But all of the experts who spoke with WebMD agree that the best treatment for moderate to severe sleep apnea is continuous positive airway pressure or CPAP. With NYU, Rapoport holds two patents on these devices.
"We usually describe CPAP as a small mask, adjusted to fit over the nose, and connected to a source of slight air pressure -- like what you'd feel going up in an elevator," Rapoport says. "It is not a breathing machine. It only holds open the airway and keeps it from collapsing. The biggest problem for patients is getting used to it and finding a comfortable enough mask. Now there are some 200 kinds of masks, so that is becoming less of a problem."
Patients don't always use their CPAP devices as often as they should. But those who do have a good chance of relief.
"I have one patient who has been on it 24 years," Rapoport says. "Those who benefit know they do and become good about it. We have about a 75% success rate. We are up against human nature here. People, even when they know it helps, don't always use the treatment."
Central Sleep Apnea
There's another kind of sleep apnea. It's called central sleep apnea. Patients with this disorder have the same cycle of choking, waking, and overbreathing. But they don't have a blockage in their throats, says University of Toronto researcher T. Douglas Bradley, MD, director of the center for cardiopulmonary sleep disorders at Toronto General Hospital.
"Central sleep apnea is seen mainly in people with heart failure," Bradley tells WebMD. "It is the lack of a signal in the brain to activate breathing."
Bradley conducted a large study to see whether CPAP can prolong the lives of heart failure patients with central sleep apnea. Unfortunately, the results were inconclusive. The problem wasn't CPAP, Bradley says. It was that during the study there were major advances in the treatment of heart failure.
"There are central sleep apnea patients who would benefit from CPAP, but we cannot tell them their survival will improve," Bradley says. "We can say your heart function will improve. CPAP increases the amount of oxygen in the blood at night. In daytime, it improves the ability of the heart to contract and increases cardiac output. And it decreases central-nervous-system activity, which, in heart failure, is the last thing you want. And it increases exercise capacity. Those are things that are important to heart patients."