Troubles du sommeil et de la vigilance dans la maladie de Steinert

Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic multisystemic disease that affects muscles, neurological system, eyes and heart. DM1 is known to cause sleep and vigilance disturbances, including excessive daytime sleepiness. Despite normal sleep efficiency, REM sleep and slow wave sleep are more important in proportion. In 22.5% of the cases, patients present restless leg syndrome, and in 63 to 86% an obstructive sleep apnea syndrome. Depending on studies, sleep apnea syndrome is predominantly central or obstructive. Excessive daytime sleepiness affects 39 to 77% of the patients and among these, 25.6 to 60% have at least two sleep onset REM (SOREMs). The pathophysiology of these symptoms remains poorly understood and various hypotheses are proposed: it could be caused by an alveolar hypoventilation, by myopathy itself, by sleep breathing impairment or pure sleep dysfunction similar to what is observed in narcolepsy. The management of these symptoms depends on the non invasive ventilation for apnea and the use of modafinil for sleepiness. Despite these treatments, improvement is usually partial because of the patients difficulty to explain precisely their complaint (fatigue, drowsiness, or apathy) which renders the care difficult and thus limits the therapeutic benefits.