Sleep Apnea and Spinal Cord Injury

If you’re constantly tired, sleep apnea may be to blame.

By Earline Gilley

When your overwhelming desire to sleep during the day becomes a prolonged problem, then it’s time to seek some help from your doctor. If you have sustained a spinal cord injury (SCI), diagnosing and treating your dilemma of daytime drowsiness will be more complicated than for someone without SCI.

Causes of Drowsiness

People with SCI tend to take medications like opioids for pain or baclofen for muscle spasms, and those medications have a tendency to cause drowsiness. They can also reduce the rate and depth of respiration, which can impact the quality of your sleep. Discuss your medications with your doctor before assuming that sleep apnea is causing your lack of energy.

Weakened respiratory muscles may cause a person with SCI to hypoventilate, and this form of shallow breathing could be a factor in daytime sleepiness. The higher the level of your spinal cord lesion, the more likely you are to have a problem with hypoventilation. Shallow breathing occurs when a person does not take deep enough breaths to properly saturate their blood with oxygen. Typically, this will occur in people with a spinal cord injury at the C-5 (fifth cervical vertebrae) level or above.

Hypoventilation and sleep apnea are not the same condition. If hypoventilation may be contributing to your drowsiness, your physician may order a pulmonary lung function test, which will assess your lung volume.

If medications or weakened respiratory muscles are not your problem, then either obstructive sleep apnea, central sleep apnea, or a combination of both types of apnea (mixed sleep apnea) may be the culprit.

Types of Apnea

Sleep apnea comes in a few flavors. The more common form, known as obstructive sleep apnea, is caused by a collapsed airway that blocks the flow of air from the mouth, into the trachea, and eventually into the lungs. If you have obstructive sleep apnea, loose tissues in the throat are completely blocking the path of air in and out of the lungs. You will struggle to breathe while the collapsed throat tissues trap carbon dioxide in the lungs and prevent oxygen from getting into the bloodstream.

The less common form, central sleep apnea, is caused by a disturbance in the area of the brain that controls the breathing muscles. In this kind of apnea, the brain fails to send the signals that would cause you to inhale and exhale in a normal, rhythmic pattern. Of those SCI patients with sleep apnea, up to 25% have central sleep apnea. In the general population, only 2% of those with apnea have a purely central pattern.

“It’s not clear why central sleep apnea is so common in the SCI population,” states Stephen P. Burns, MD, from the VA Puget Sound Health Care System, “It may involve feedback from the chest wall. Somehow the brain stem is not getting all of the information it needs to prompt breathing.”

The third form of sleep apnea is a mixture of both obstructive and central sleep apnea. Recent studies show that mixed sleep apnea is more common than previously thought. Often people with central sleep apnea also have some degree of obstruction. “The term ‘mixed sleep apnea’ can be used in a couple of different ways,” states Dr. Burns, “It could be that the study results show episodes that are obstructive apneas and episodes that are central apneas. There are also individual episodes of apneas that start as central, with no effort to breathe. As the seconds tick by, the person starts an effort to breathe, but there is an obstruction in airflow until the person wakes up.”

Diagnostic Difficulties

There are a variety of reasons that diagnosing sleep apnea in the SCI population is so difficult. The typical path to diagnosing sleep apnea is to visit a clinic for a polysomnography, also known as a sleep study.

Forewarning the sleep lab that you are a patient with SCI and that you will need assistance, extra time, and position changes in the night is important for both you and the personnel at the lab.

Since visiting a sleep lab may prove difficult for people with SCI, there are some alternatives to the traditional polysomnography lab. Portable sleep testing is performed in the patient’s home; it measures blood oxygen levels, airflow through the mouth and nose, and breathing effort. Unfortunately, it does not measure brain waves. Portable polysomnography adds the extra component of brain wave measurement and, thus, can provide far more information about the patient’s sleep staging.

Although these options are not common, they may be available in some areas, and they may prove to be much more convenient for people with SCI than a traditional sleep lab visit.

In a hospital or rehabilitation center, there may be an option to perform a limited sleep study, also known as a cardiopulmonary sleep study. The limited study does not include a reading of the brain waves. People who are not sleep technicians, such as respiratory therapists and nurses, are able to set up the necessary equipment easily, and the study results are easier to interpret than those from a full polysomnography.

Treatment

Treatment of sleep apnea varies depending upon the severity of the condition. For the mildest of cases, there are a few proactive steps you can take to decrease the number of apnea episodes.

First, weight loss is a great place to start. If you have SCI, you may be limited in the amount of physical activity you can take on, but for most SCI levels there are some exercise options. Chris Smith, a C-4 quadriplegic, is able to use his deltoids to move his upper arms, so an exercise he likes to do is to tap a balloon back and forth with his niece. This seemingly minimal exercise provides him with some aerobic activity, which, in conjunction with a healthy diet, can assist with weight loss.

If weight loss is not an option, or if excessive weight is not an issue with your sleep apnea, then changing your sleeping position may reduce the number of disturbed breathing episodes. According to Dr. Burns, about two thirds of all people with SCI prefer to sleep on their backs, but sleeping on your side can significantly improve the quality of your sleep. By simply rolling to the left or right side and placing wedges behind the back for stability, a person with mild apnea can dramatically reduce the periods of breathing obstruction.

CPAP and BiPAP

If you have a moderate to severe case of sleep apnea, then you will most likely be fitted with a mask and a CPAP or BiPAP—continuous vs. bi-level positive airway pressure— machine. These machines are medical-grade air compressors that force air into a person’s mouth and throat. The goal of CPAP and BIPAP is to mechanically open an obstructed airway so that air can pass easily in and out of the lungs.

The difference between a CPAP and BiPAP is in the pressure of air delivered to the patient. CPAP forces air at a constant pressure, whether the patient is inhaling or exhaling. BiPAP has two levels of pressure: a higher one for inhalation and a lower one for exhalation. If you have limited use of your diaphragm or chest wall muscles, BiPAP may be a better alternative. Upon exhaling, you won’t have to struggle against a high pressured blast of air, and when you inhale you will have some breathing assistance.

One of the hardest things to contend with during treatment of sleep apnea is the facial mask or nasal pillows you will wear nightly. Whether you are using CPAP or BiPAP, it is essential that the mask or pillows be sealed tightly to avoid air leaks. Finding the right mask for you may be a challenge, but it is important not to give up on the treatment altogether just because a particular mask isn’t working. There are masks which cover only the nose; full face masks which cover the nose and mouth; nasal pillows; nasal prongs; an oral mask that delivers air through a mouthpiece only; and a total face mask the extends from the forehead to the chin.

If you have a higher level of SCI that limits your ability to move the mask in the night, then you may have to try several different types of masks or dental appliances before you find the one that works for you. You may also need to work with an occupational therapist to help you modify the strap system of the mask.

Conclusion

Getting a proper diagnosis of sleep apnea can be time-consuming for any person, but it comes with some extra obstacles for people with SCI. Educating yourself about the diagnostic process, providing care providers with as much information about your condition as possible, and obtaining assistance prior to your visit to the sleep lab or requesting an at-home sleep test may increase your chances for getting an accurate diagnosis.

Once you have been diagnosed, you should probably expect to have some issues with your mask. It’s important to investigate the variety of mask options, and if your first mask doesn’t work, don’t get discouraged. Keep trying until you find something that works for you. Once you get the right combination, daytime drowsiness may become a thing of the past.

Earline Gilley is a freelance writer based in Jacksonville, Florida.