Sleep and breathing in multiple system atrophy.

Sleep disorders are common manifestations in multiple system atrophy (MSA) and include reduced and fragmented sleep, excessive daytime sleepiness, rapid eye movement (REM) sleep behavior disorder (RBD), stridor, and sleep-disordered breathing. RBD and nocturnal stridor are considered red flags and may be the first symptoms of the disease. RBD occurs in 90% to 100% of the patients, indicating severe and widespread pathologic impairment in the brain structures that regulate REM sleep. In 50% of the patients, RBD precedes the onset of waking motor symptoms and autonomic failure by several years. Sleep-disordered breathing manifests as 1) central hypoventilation that reflects impaired automatic control of ventilation secondary to degeneration of the pontomedullary respiratory centers; and, more commonly, as 2) stridor and obstructive sleep apnea due to larynx narrowing secondary to combined vocal cord abductor paralysis and excessive adductor activation during inspiration. Nocturnal stridor is a life-threatening condition in MSA associated with respiratory failure and sudden death during sleep. Long-term treatment with continuous positive airway pressure (CPAP) eliminates nocturnal stridor. Tracheostomy is advised when CPAP is not tolerated and stridor occurs during wakefulness.