Among myasthenia gravis patients (MG), males and those with a higher body mass index are at a higher risk of obstructive sleep apnea, which is similar to what has been been reported in the general population, a study shows.
The study, “Characteristics of obstructive sleep apnea in myasthenia gravis patients: a single center study,” was published in the journal Neurological Sciences.
Obstructive sleep apnea is a condition that causes breathing to repeatedly stop and start during sleep due to the throat muscles intermittently relaxing and blocking the airways.
As a result, people with obstructive sleep apnea often experience daytime sleepiness, but the condition is also linked to cardiovascular problems and metabolic dysfunctions.
Recent studies have shown that, compared with the general population, MG patients have a higher prevalence of obstructive sleep apnea, estimated to affect 36-64 percent of them.
However, only a few studies have investigated the association of obstructive sleep apnea and MG.
To address this, a group of researchers in South Korea studied 18 patients diagnosed with stable MG, of whom seven had obstructive sleep apnea and 11 did not.
They looked at patients’ medical records to obtain information on several clinical parameters, namely sex, age, duration of the disease, prescribed medications, and whether they had undergone surgical removal of the thymus (thymectomy), as well as if they were positive for antibodies against the acetylcholine receptor (AChR) and muscle-specific tyrosine kinase (MuSK).
Researchers also calculated the participants’ body mass index (BMI) — a measure of body fat — and assessed their pulmonary function.
All participants underwent an overnight polysomnography test, which is used to diagnose sleep disorders.
Results showed that MG patients with obstructive sleep apnea were most often male and had an increased BMI, both of which were identified as statistically significant factors for obstructive sleep apnea.
“Several studies have reported male sex and BMI as independent risk factors for OSA in the normal population,” the researchers wrote.
Moreover, the sleep analysis revealed that the severity of the sleep apnea, measured with the Apnea-Hypopnea Under (AHI), was 11 times higher in MG patients with obstructive sleep apnea, specifically for those with supine-sleep apnea, which occurs when the person is lying face up on his or her back.
“This study showed that the occurrence of OSA [obstructive sleep apnea] in patients with MG is associated with male sex and obesity, which is in accordance with the normal population,” the researchers wrote.
“Supine dominant OSA was more frequently observed in MG with OSA,” they added, indicating that “proper treatment strategies for OSA in MG may be applied based on our results, that may eventually lead to better quality of sleep in stable MG patients.”