[Sleep disorders in multiple system atrophy]

Sleep disorders are so common in multiple system atrophy that they should be considered an integral part of the disease. Sleep fragmentation occurs in more than half of the patients, with sleep onset and sleep maintenance insomnia. Periodic leg movements of sleep are also common, although they are generally asymptomatic. REM sleep behavior disorder, a parasomnia in which the patient presents vigorous movements associated with intense dreaming dreaming during REM sleep, is detected polysomnographically in almost all the patients with variable severity. Nocturnal stridor is produced by obstruction on the glottis level. The cause of stridor is unknown but two alternative explanations have been proposed: paralysis of the muscles opening the vocal chords and excessive contraction of the muscles that close them. A combination of both, however, is the most likely explanation. Nocturnal stridor is associated with decreased survival and its treatment is based on continuous positive air pressure (CPAP) when it occurs only during sleep or tracheostomy when it worsens and becomes also diurnal.