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Tongue fat may become key in treating sleep apnea

Does my tongue look fat? Goofy as that query may sound, it could become an important part of the diagnosis, and maybe even the treatment, of sleep apnea in fat people, suggests a new study by University of Pennsylvania researchers.

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Does my tongue look fat?

Goofy as that query may sound, it could become an important part of the diagnosis, and maybe even the treatment, of sleep apnea in fat people, suggests a new study by University of Pennsylvania researchers.

Obesity has long been recognized as a risk factor for sleep apnea, but the study is the first to point to the tongue as a likely culprit. It found that obese adults with the sleep disorder had bigger and fattier tongues than obese people without apnea.

"When you talk to patients, they're like, 'Wow, I didn't know there was so much fat in the tongue,' " said Penn sleep medicine physician Richard J. Schwab, senior author of the study in the current issue of the journal Sleep. "Most physicians have no idea."

Indeed, the tongue is not high on the list of body parts that the obesity epidemic makes people worry about.

That should change, said American Academy of Sleep Medicine president Timothy Morgenthaler.

"Tongue size is one of the physical features that should be evaluated by a physician when screening obese patients to determine their risk for obstructive sleep apnea," he said.

Apnea - dangerous pauses in breathing during sleep, caused when the airway collapses or becomes blocked - afflicts 15 million Americans, and it is linked to high blood pressure, heart disease, diabetes, stroke, and depression, not to mention daytime sleepiness.

For 20 years, sleep scientists at Penn and elsewhere have studied the anatomy of the upper airway and throat to try to understand the disorder.

Schwab's team turned its focus to the tongue - the only bodily muscle that is anchored to bone at just one end - for several reasons. A study of mutant obese mice found that those with fat tongues had narrowed upper airways. A California autopsy study found that human tongue weight and fattiness increased in relation to obesity.

But that study "harvested" and weighed tongues outside the body.

The Penn researchers, in contrast, did specialized MRI scans and sophisticated three-dimensional reconstructions to compare the tongues of 90 obese apnea sufferers with the tongues of 31 obese controls who had no apnea.

On average, the apneics' tongues were six cubic inches, and 33 percent of that volume was fat. The controls' tongues were about five cubic inches and 28 percent fat.

The apneics' extra tongue fat was also concentrated at the base of the organ, close to the throat airway.

Although family doctors could not make such high-tech measurements, they wouldn't have to, Schwab said. They could be taught to recognize signs of a fat tongue.

"Most doctors look at the tongue for redness or signs of infection," Schwab said. "But once you start looking [at size], it's easy."

Therapies - which are yet to be tested - could be as obvious as losing weight or doing exercises to strengthen airway muscles, or as radical as surgery to remove a hunk of the tongue, Schwab said. (A recent study found that cutting away part of the tongue base did indeed help apneics who had not responded to standard treatments such as air pressure machines during sleep.)

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