Sleep-related stridor due to dystonic vocal cord motion and neurogenic tachypnea/tachycardia in multiple system...

Sleep-disordered breathing and sleep-related motor phenomena are part of the clinical spectrum of multiple system atrophy (MSA). Stridor has been attributed to denervation of laryngeal muscles or instead to dystonic vocal cord motion. We studied 3 patients with nocturnal stridor in the setting of MSA. All patients underwent nocturnal videopolysomnography (VPSG) with breathing and heart rate, O(2) saturation and intra-esophageal pressure recordings, and simultaneous EMG recordings of the posterior cricoarytenoid, cricothyroid, and thyroarytenoid muscles and continuous vocal cord motion evaluation by means of fiberoptic laryngoscopy. VPSG/EMG and fiberoptic laryngoscopy documented normal vocal cord motion without denervation during wake and stridor only during sleep when hyperactivation of vocal cords adductors appeared in the absence of significant O(2) desaturation. All patients had tachycardia and tachypnea and paradoxical breathing during sleep, erratic intercostalis and diaphragmatic EMG activity and Rem sleep behavior disorder. One of the patients had restless legs syndrome with periodic limb movement during sleep and excessive fragmentary hypnic myoclonus. In conclusion, our patients with MSA had nocturnal stridor due to sleep-related laryngeal dystonia. Stridor was associated with other abnormal sleep-related respiratory and motor disorders, suggesting an impairment of homeostatic brainstem integration in MSA.