Acoustic Characteristics of Stridor in Multiple System Atrophy

• Published in: PloS one 2016-04, Vol.11 (4), p.e0153935-e0153935
• Main Authors: Koo, Dae Lim, Lee, Jee Young, Joo, Eun Yeon, Hong, Seung Bong, Nam, Hyunwoo
• Format: Article
• Language: English
• Subjects: Acoustic properties; Acoustics; Aged; Analysis; Atrophy; Biology and Life Sciences; Biomedical research; Breathing; Continuous Positive Airway Pressure - methods; Engineering and Technology; Female; Humans; Male; Medical prognosis; Medicine; Medicine and Health Sciences; Middle Aged; Multiple system atrophy; Multiple System Atrophy - physiopathology; Neurology; Patients; Physical Sciences; Polysomnography; Polysomnography - methods; Prognosis; Respiration; Respiratory Sounds - diagnosis; Respiratory Sounds - physiopathology; Rhythms; Sleep; Sleep Apnea, Obstructive - diagnosis; Sleep Apnea, Obstructive - physiopathology; Sleep disorders; Snoring - diagnosis; Snoring - physiopathology; Sound; Stridor; Studies; Survival; Waveforms
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0153935

Nocturnal stridor is a breathing disorder prevalent in patients with multiple system atrophy (MSA). An improved understanding of this breathing disorder is essential since nocturnal stridor carries a poor prognosis (an increased risk of sudden death). In this study, we aimed to classify types of stridor by sound analysis and to reveal their clinical significance. Patients who met the criteria for probable MSA and had undergone polysomnography (PSG) were recruited. Patients were then assessed clinically with sleep questionnaires, including the Pittsburgh Sleep Quality Index, and the Hoehn and Yahr scale. Nocturnal stridor and snoring were analyzed with the Multi-Dimensional Voice Program. Nocturnal stridor was recorded in 22 patients and snoring in 18 patients using the PSG. Waveforms of stridors were classified into rhythmic or semirhythmic after analysis of the oscillogram. Formants and harmonics were observed in both types of stridor, but not in snoring. Of the 22 patients diagnosed with stridor during the present study, fifteen have subsequently died, with the time to death after the PSG study being 1.9 ± 1.4 years (range 0.8 to 5.0 years). The rhythmic waveform group presented higher scores on the Hoehn and Yahr scale and the survival outcome of this group was lower compared to the semirhythmic waveform group (p = 0.030, p = 0.014). In the Kaplan Meier's survival curve, the outcome of patients with rhythmic waveform was significantly less favorable than the outcome of patients with semirhythmic waveform (log-rank test, p < 0.001). Stridor in MSA can be classified into rhythmic and semirhythmic types and the rhythmic component signifies a poorer outcome.