Most patients with myotonic dystrophy type 1 (DM1) also suffer from respiratory and sleep disorders. DM1 is the most common form of muscular dystrophy found in adults. Recent research published in the Journal of Neuromuscular Diseases notes that due to the variety of sleep difficulties in DM1 patients, the treatments often do not work on a one-size-fits-all model.
Sophie D. West, MD, lead investigator of the study from Newcastle Regional Sleep Service, Newcastle upon Tyne Hospitals in the UK, notes that patients with myotonic dystrophy type 1 frequently suffer from severe daytime sleepiness, with anywhere between 33% and 80% of patients reporting problems. She notes that there may be other contributing problems leading to the sleepiness like obstructive sleep apnea (OSA), periodic limb movements in sleep, poor sleep patterns, respiratory failure, or narcolepsy.
Overnight sleep studies were given to all DM1 patients who showed signs of severe daytime sleepiness in their annual follow-up visits between May 2011 and May 2015 at John Walton Muscular Dystrophy Research Center in Newcastle upon Tyne. In 120 DM1 patients, scientists found that 30% showed intrinsic sleepiness on the Epworth Sleepiness Score (ESS), 27% experienced respiratory failure, and 18% suffered from OSA.
Patients were put into one of four groups:
Treatments were administered for the individual symptoms, including use of the drug modafinil for daytime sleepiness, non-invasive ventilation for respiratory failure, and continuous positive airway pressure (CPAP) for OSA patients.
The study showed that only 29% of patients continued the therapies and reported benefits. This was an unexpectedly lower result than what would be seen in other patient populations, suggesting that additional research is needed to identify if DM1 patients are more likely to benefit from targeted therapy. Additional research is also needed to find the most effective way to deliver targeted therapies to these patients.
To improve target therapies for DM1 patients, researchers recommend classifying these patients in three types of sleep disturbances, as listed above. Those with high ESS scores, light use of sedatives, and no restless leg syndrome, modafinil showed good results for daytime sleepiness. For those with OSA without respiratory failure, the standard CPAP treatment would be beneficial. For patients with daytime respiratory failure and abnormalities on sleep studies, providers should try noninvasive ventilation techniques.
There are varying levels of muscular and respiratory impairment, as well as sleepiness in all muscular dystrophy patients. The disease is heterogeneous in nature. Dr. Sophia West notes that this data is extremely valuable for those who are working toward better treatment methods for DM1 patients with excessive daytime sleepiness. These findings support their efforts with detailed sleep tests and targeted therapies that will, hopefully, improve symptoms in the long-run.
Rachael Herman is a professional writer with an extensive background in medical writing, research, and language development. Her hobbies include hiking in the Rockies, cooking, and reading.
© 2020 American Sleep Association.