February 15, 2014
Sleep Apnea May Contribute To Fatigue In Multiple Sclerosis
April Flowers for redOrbit.com - Your Universe Online
The fatigue that many people with multiple sclerosis (MS) feel is often written off as just being part of the territory of their chronic neurological condition.
A new study from the University of Michigan, published in the Journal of Clinical Sleep Medicine, suggests that a large number of MS patients might have an undiagnosed — and treatable — sleep disorder, known to cause fatigue: obstructive sleep apnea, or OSA.
The research team, from the U-M Health System's Sleep Disorders Center, conducted a study involving 195 patients at the U-M Multiple Sclerosis Center. Based on a method of screening for the condition known as the STOP-Bang questionnaire, they found that 56 percent were at an increased risk for OSA. Most of those had never had a formal diagnosis, however, and less than half who had been told they had sleep apnea were using standard treatment for it.
The results also showed that patients who were more fatigued were more likely to have an increased risk for sleep apnea. This was true even factoring in other aspects that might have contributed to feelings of fatigue, such as age, gender, body mass index (BMI), sleep duration, depression, and other nighttime symptoms.
The results are based on data gathered from one questionnaire designed by the authors, and four validated instruments designed to assess daytime sleepiness, fatigue severity, insomnia severity and obstructive sleep apnea risk. The researchers also accessed the patients' medical records to examine clinical characteristics that may predict fatigue or obstructive sleep apnea risk.
"We were particularly surprised by the difference between the proportion of patients who carried an established diagnosis of obstructive sleep apnea – 21 percent - and the proportion at risk for obstructive sleep apnea based on their STOP-Bang scores, which was 56 percent," says Tiffany Braley, MD, MS.
"These findings suggest that OSA may be a highly prevalent and yet under-recognized contributor to fatigue in persons with MS. Our study suggests that clinicians should have a low threshold to evaluate MS patients for underlying sleep disturbances."
The research team consisted of Braley, who is an assistant professor of Neurology and multiple sclerosis specialist at the U-M Medical School; Ronald Chervin, MD, MS, director of the U-M Sleep Disorders Center; and Benjamin Segal, MD, director of the U-M MS Center.
MS is an immune-mediated disease of the central nervous system. It causes inflammation and damage of the brain and spinal cord, as well as a number of chronic symptoms. For MS patients, fatigue is one of the most disabling of the chronic symptoms.
"Obstructive sleep apnea is a chronic illness that can have a destructive impact on your health and quality of life," said American Academy of Sleep Medicine President Dr. M. Safwan Badr. "People with multiple sclerosis who are found to have a high risk of OSA should be referred to a board certified sleep medicine physician for a comprehensive sleep evaluation."
Braley cautions that the researchers can't prove that the patients felt more fatigued because they had a high score on a sleep apnea risk survey simply based on survey results. However, she notes, "the findings should prompt doctors who treat MS patients to consider sleep apnea as a possible contributor to their patients' fatigue, and recommend appropriate testing and treatment."
Traditionally, sleep apnea is treated with a CPAP, or continuous positive airway pressure, machine. The CPAP machine has a mask device that applies a stream of air to the upper airway to keep it open during sleep.
The study participants had an average age of 47 and, on average, had lived with MS for 10 years. Consistent with the prevalence of MS in the United States, two-thirds of the participants were female and two-thirds were taking a medication to treat their MS, while three-quarters had the relapsing-remitting form of the disease.
MS is the most common disabling neurological disease among young adults, with approximately 400,000 people in the US affected, according to the National Multiple Sclerosis Society. OSA affects up to seven percent of men and five percent of women, according to the American Academy of Sleep Medicine.