Treating Sleep-Related Symptoms in Muscular Dystrophy Proves Difficult

Findings from a new study suggest that targeted treatments for sleep disorders may help treat patients with myotonic dystrophy type 1 (DM1), a type of adult onset muscular dystrophy.

DM1 is a generic disorder characterized by symptoms related to the skeletal and smooth muscle, and can affect the eyes, heart, endocrine, and central nervous systems. Patients experience progressive muscle loss and weakness, and may have physical and mental disabilities.

Many patients with muscular dystrophy experience sleep and respiratory disorders as a result of their condition. In a new study published by the Journal of Neuromuscular diseases, investigators found that interventions that target each individual patient are the most effective.

“Excessive daytime sleepiness is a common problem for people with myotonic dystrophy, affecting between 33% and 80% of patients,” said lead investigator Sophie D. West, MD. “Other contributing causes can be attributed to poor sleep patterns, obstructive sleep apnea (OSA), respiratory failure, periodic limb movements during sleep, or narcolepsy features."

From 2011 to 2015, 120 patients with DM1 who displayed symptoms of daytime sleepiness at the John Walton Muscular Dystrophy Research Centre were referred for a sleep assessment, according to the study. Of these patients, 18% had OSA, 27% had respiratory failure, and 30% had intrinsic sleepiness.

Patients were then split into groups based on sleep condition, and a control group of patients with no sleep-related symptoms were created. The researchers then implemented treatments based on their symptoms.

Patients with OSA were treated with continuous positive airway pressure (CPAP), patients with respiratory failure were treated with non-invasive ventilation (NIV), and patients with excessive daytime sleepiness were treated with modafinil, according to the study.

However, only 29% of patients included in the trial had observable benefits from the treatments, and continued treatment after the study concluded. The study authors said these results were lower than expected, and further studies are needed to determine which patients would likely benefit the most from targeted therapy.

The authors recommend that patients with DM1 and sleep symptoms be classified into 3 groups to ensure the proper treatment. Patients who high daytime sleepiness, but no restless leg syndrome or sedative use, should be treated with modafinil.

For patients with OSA with no daytime respiratory failure, CPAP should be the first-line treatment. Patients with daytime respiratory failure and an abnormal sleep study should be treated with NIV, according to the study.

"This is valuable data for those people in the myotonic dystrophy community with excessive sleepiness, to support them in having detailed sleep tests and targeted individualized therapies, hopefully to improve their symptoms,” Dr West concluded.