What are the causes of Obstructive Sleep Apnea?

I often have patients asking me why he/she has Obstructive Sleep Apnea(OSA), the disease where breathing stops intermittently (apnea) during sleep. Well, my answer to most of them is – its because of the weight you have gained. They are then advised to lose weight and it does help, besides the mainstay of therapy – the PAP device. Yet, some other times, I have younger patients who are not obese and have good physique, still get diagnosed to have OSA. The explanation to them is slightly different. Today I want to list to you all the possible reasons which alone or together lead to OSA. But, first – some lessons on the upper airway structure in an extremely simplified way.

Our upper airway from the mouth and nose to the Adam’s apple in the throat is a soft collapsible muscular tube. During sleep, our muscles tend to relax, thus narrowing the tube. This narrowing increases considerably in some, causing OSA . The important reasons are :

Weight Gain:
- With weight gain, fat gets deposited around the airway . This presses upon the airway tube and closes it.
- With extra fat in your belly, lungs in your chest are pushed up, so the body’s pull on the upper airway is decreased, increasing the collapse.
Structural abnormality of facial bones :
- There are quite a few things that are genetically determined which can predispose to narrowing our upper airway, for example, the size and position of the upper and lower jaw. If you have a short mandible or there is too little space between the upper and lower jaw , it can compress upon your airway tube, causing OSA.

Tongue Abnormalities: Similarly, if you have a slightly large or a lax tongue, it can impinge upon airway, leading to OSA. Similarly, large uvula and enlarged tonsils also add to compress the airway at times.
Muscle disorders: Sometimes, genetic disorders causing muscular weakness or some change in quality of muscles of the airway ( due to vibration by snoring, low oxygen due to OSA, etc) lead to apneas.
Nasal Obstruction: Trauma, injury to the nose especially in childhood, allergies or deviated septum of nose lead to mouth breathing, which also predisposes to airway closure .
Others: There can be other complex causes like abnormal breathing response to blood oxygen and carbondioxide levels from brain, racial predisposition to airway collapse, etc which can cause sleep apnea. As a patient it is also important to know that use of alcohol and sleeping pills aggravate your apneas by acting on your brain and muscles of throat .

I believe you now have a fair idea of what it takes to cause OSA and that it is a disease with multiple contributing causes. PAP therapy works well in most patients regardless of the causes. Weight loss, exercises and certain types of airway surgery also help in addition to PAP therapy. Scientists are actively engaged in developing new methods to treat OSA based on the above information on its causes. Hope in near future we will have an individualized treatment scheme available for managing OSA.