sleep apnea and cardiovascuar disease

The evidence linking obstructive sleep apnea to cardiovascular disease continues to grow. Obstructive sleep apnea (OSA) is a thought to be a risk factor for the development of hypertension, stroke, coronary artery disease, and congestive heart failure. The evidence is strongest for hypertension. A recent study adds to the evidence linking OSA to stroke:

But the real question, Dr. Mohsenin said, is whether there is an independent association between sleep apnea and stroke, and a recent study on which he was an author shows that there is indeed such an association.
In the observational cohort study of 697 patients with obstructive sleep apnea and 325 controls (mean apnea-hypopnea index of 35 vs. 2 in the patients and controls, respectively), obstructive sleep apnea was found to have a statistically significant association with stroke or death (hazard ratio of 1.91) after adjustment for numerous factors, including age, sex, race, smoking status, alcohol consumption, body mass index, diabetes, hyperlipidemia, atrial fibrillation, and hypertension.
A trend analysis also showed a significant dose-response relationship between sleep apnea severity at baseline and development of a composite end point of stroke or death from any cause (N. Engl. J. Med. 2005;353:2034–41).
While randomized controlled trials are needed to firmly establish a causal link between sleep apnea and stroke—to “put the last nail in the coffin and say, ‘ok, sleep apnea is indeed a cause of stroke in a high-risk patient population,’” as Dr. Mohsenin put it, the findings increasingly suggest this is the case. Also, sleep apnea occurs as commonly in transient ischemic attack as it does in stroke, further underscoring the need for sleep apnea treatment in affected patients, he noted.
Additionally, a number of studies have shown that sleep apnea is associated with worse functional outcomes in stroke patients, Dr. Mohsenin said.
Patients with stroke who have sleep apnea have been shown to have more delirium, depression, impaired functional capacity, longer rehabilitation time, and longer hospitalization, he said.
“Sleep apnea does affect the outcome of stroke,” he said, noting that in some studies these effects lasted out to 12 months.
Patients who have had a stroke should be evaluated for sleep disordered breathing, he advised.

That the treatment of OSA improves cardiovascular outcomes is an unproven assumption. We know that in sleep apnea patients, CPAP can improve cardiac functioning (ejection fraction) and reduce blood pressure. However, it has not been proven that CPAP improves mortality or decreases the rate of myocardial infarction. A randomized controlled trial looking at this question would be difficult to carry out.

Kleine-Levin Syndrome

A British newspaper reports on a woman with Kleine-Levin Syndrome (via Kevin MD):

Miss Hoyland, a 26-year-old youth charity worker, is one of only a handful of Britons to suffer a rare sleep disorder which can cause her to stay in bed for up to a week at a time.

She wakes only to snack on whatever food is available and visit the bathroom before relapsing into a dream-like state.

The attacks started when she was 17 and studying for her A-levels - forcing her to take weeks off school to sleep.

After graduating she was working as a sales assistant when one day she became woozy and had to sit down, then minutes later she was snoozing in the staff room.
Since then she has suffered 'sleeping episodes' for a week every two months.

It took a further eight years until specialists correctly diagnosed her with Kleine-Levin Syndrome, known more commonly as sleeping beauty disease.
Thought to be caused by a chemical abnormality in the base of the brain where sleep and appetite is governed, the incurable neurological disorder affects fewer than 1,000 victims worldwide.
Sufferers are often uncontrollably hungry when they awake and it can affect sex drive as well as behaviour.
There is no cure, but the condition can be treated by a combination of behavioural therapy and stimulant drugs to stay awake.

Kleine-Levin Syndrome is a rare disorder (less than 200 cases reported in the literature, according to The International Classification of Sleep Disorders, 2nd edition, 2005). Episodes of sleepiness last several days to several weeks, and occur 1-10 times per year. During sleep episodes, patients sleep as much as 18 hours a day, waking or getting up only to eat and void. During episodes, binge-eating, confusion, aggression, and hypersexuality may be present.

The NINDS website has a good summary of the disorder.

I hope this patient's doctors are writing up the case and studying her polysomnographically both during and between episodes to add to the limited scientific literature about this disorder.

New Sleep Textbook

Sleep Disorders and Neurologic Diseases, Second Edition has just been published.
Here is a description:
"Entirely devoted to the relationship between sleep and brain function, and the improved management of sleep in patients with neurologic diseases, this completely updated Second Edition includes new sections on the role of hypothalamic dysfunction in narcolepsy and the emerging relationship between sleep apnea and hypertension, heart disease, and stroke. With chapters analyzing the treatment of specific disease states, this convenient guide offers recommendations for the management of primary sleep disorders, sleep disorders secondary to well-established neurological disorders, and the neurological consequences of uncontrolled sleep conditions."
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I received an advance copy a few days ago and highly recommend it to sleep physicians and trainees.

Sleep Apnea in football players

The New York times discusses the health problems of football players, including obstructive sleep apnea:
According to a 2003 study published in The New England Journal of Medicine, 14 percent of N.F.L. players had obstructive sleep apnea, a disease that impairs breathing and is known to affect large, muscular individuals like football linemen more often than people of average size. Reggie White, a Hall of Fame defensive lineman, died at 43 in 2004 after having cardiac arrhythmia, but he also had sleep apnea, which may have contributed to his death.
With more football linemen weighing much more than 300 pounds, doctors said they expected sleep apnea to become more prevalent .
“The primary treatment for sleep apnea is to lose weight, and they can’t,” said Dr. Allan Levy, an associate team physician with the Giants, who is assisting with this week’s screening. “There’s no such thing as a 225-pound offensive lineman. We try to make certain that they understand that they’ve got to come down in weight when they retire. All of my offensive lineman from the Giants’ two Super Bowl wins have all lost at least 50 pounds. They’re all in excellent health. You see some of the other guys, and they’re just huge. They’ve got all kinds of problems.
“The problem with sleep apnea is in the neck. A 17½-inch neck is usually where the problem begins. When they sleep, the muscles relax in the body. Now the weight of their neck clasps down on their airway. They stop breathing. They momentarily wake up, then the cycle starts over again, and they never get into deep sleep. They develop heart disease and hypertension. Sleep apnea is a killer. One of the kids that played for us, we did a sleep study on, had 440 awakenings during the night.”
The most common treatment for sleep apnea involves wearing a mask that supplies a stream of air through the nose during sleep.
Increased neck size and obesity are 2 major risk factors for obstructive sleep apnea.