To determine whether tremulous arytenoid movements predict the severity of glottic stenosis in patients with multiple system atrophy (MSA), 28 MSA patients and 14 age-matched controls underwent fiberoptic laryngoscopy with video monitoring during wakefulness and under anesthesia induced by intravenous injection of propofol. Presence or absence of tremulous arytenoid movements was recorded during wakefulness. The ratio of glottic stenosis (%), which represents the extent of airway narrowing under anesthesia, was obtained by measuring the inspiratory glottic angle during wakefulness and under anesthesia. The median ratio of glottic stenosis was significantly higher in patients with MSA (57.5%) than in control subjects (0.5%). Tremulous arytenoid movements were characterized by shaking movements of the arytenoid region including the vocal folds, which are most apparent in the arytenoid cartilage. In this study, tremulous arytenoid movements were observed in 18 (64.2%) of 28 patients with MSA, who displayed a significantly higher median ratio of glottic stenosis (71.2%) than other patients (34.9%). None of the control subjects exhibited tremulous arytenoid movements. A clear correlation existed between the ratio of glottic stenosis and disease duration. Our observations indicate that tremulous arytenoid movements are a marker of the severity of glottic stenosis, which confers an increased risk of upper airway obstruction in patients with MSA. (C) 2010 Movement Disorder Society