Sleep Apnea Diagnosis

If your doctor suspects that you have sleep apnea, you will need a thorough examination of your mouth, nose, throat, and neck to make sure that there are no problems with those tissues or structures.

Your doctor will ask you about sleep habits—if you snore and if your bed partner witnesses that you stop breathing. You will also be asked about daytime sleepiness, fatigue, and if you easily fall asleep. The doctor may complete a screening form such as the Epworth Sleepiness Scale (ESS).

There are two tests that can help in the diagnosis of sleep apnea: the polysomnogram and the multiple sleep latency test. A sleep specialist usually administers both of these tests in an overnight sleep laboratory.

Polysomnogram Test (Sleep Study)

For this test, you spend the night in a sleep center. Tiny electrodes are attached to various areas of your body in order to closely monitor your heart rate, eye movements, brain waves, and muscle activity throughout the night. Monitors also record your pulse rate, information about your breathing, changes in the concentration of oxygen in your blood, and your body position. An EKG machine keeps track of whether you have any changes in your heart’s rhythm during sleep. The number of apnea events is recorded.

Read more about Polysomnography.

Multiple Sleep Latency Test

This test is usually done the day after the polysomnogram. With the same set of electrodes still attached, you are asked to take a series of 20-minute naps, every two hours throughout the day. The electrodes provide information about how quickly you fall asleep and how quickly you reach various levels of sleep, particularly the level called REM (rapid eye movement) sleep. This test can help determine your level of daytime sleepiness, which is a result of apnea episodes causing insomnia. If you fall asleep in five or fewer minutes, it may be an indication of extreme sleepiness due to sleep apnea. This test is most often performed to evaluate for other sleep disorders such as narcolepsy, and is often not necessary in the evaluation of sleep apnea.

If you have obstructive sleep apnea, you may undergo the same test again, while wearing a face mask that provides positive pressure. This is called continuous positive airway pressure (CPAP). This mask is supposed to prevent the collapse of your airway and maintain your breathing during the night. At times, evaluation with CPAP can occur during the second half of the night after evaluation without CPAP. This is called a split-night study.

Other Tests

If you’re suspected of having central sleep apnea (which is much less common than obstructive sleep apnea), you may need a variety of other tests to diagnose an underlying medical condition. Your doctor will have to determine what other symptoms you have and use these symptoms to guide his choice of further studies.

Possible other tests include:

• Blood tests
• Echocardiogram
• MRI or CT scans of your brain
• Electroencephalogram (EEG) studies—brain wave studies
• Electromyogram (EMG) studies—studies of electrical conduction along nerves

• Screening for Sleep Apnea

References:

American Academy of Otolaryngology-Head and Neck Surgery website. Available at: http://www.entnet.org/ . Accessed September 17, 2008.

American Sleep Apnea Association website. Available at: http://www.sleepapnea.org/resources/pubs/evaluated.html . Published May 2005. Accessed September 17, 2008.

Cecil R, Goldman L, Benett JC. Cecil Textbook of Medicine.21st ed. Philadelphia, PA: WB Saunders Company; 2000.

NINDS sleep apnea information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/sleepapnea/sleepapnea.htm . Updated June 2008. Accessed September 17, 2008.

What is sleep apnea? National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/dci/Diseases/SleepApnea/SleepApnea_WhatIs.html . Updated February 2008. Accessed September 17, 2008.