Natural course and potential prognostic factors for sleep-disordered breathing in multiple system atrophy

Multiple system atrophy (MSA) frequently results in the development of sleep-disordered breathing (SDB). Few reports have described the natural course of this phenomenon. The aim of the present study was to determine the natural course of SDB and prognostic factors associated with such conditions in MSA.

Twenty-four consecutive patients were recruited with probable MSA, who had not been treated with continuous positive airway pressure (CPAP) and had undergone overnight polysomnography (PSG) more than once following the development of snoring or stridor. Based on changes in the apnea-hypopnea index (AHI) over the course of the disease, patients were divided into two groups (AHI-maintained and AHI-deteriorated) and the clinical findings were compared.

Mean duration between the first and last PSG was 2.4 ± 1.5 years, and patients underwent PSG assessment an average of 2.5 ± 0.6 times during this period. During this interval, AHI increased from 19.4 ± 22.8/hour to 34.4 ± 30.1/hour (p = 0.006), although spontaneous improvement was observed in 29% of patients. Following the first PSG, all patients were diagnosed with obstructive sleep apnea; however, the SDB type changed from obstructive sleep apnea to central sleep apnea in 3 of the 24 (13%) patients during the period between the first and last PSG.

Although SDB associated with MSA exacerbates with disease progression, spontaneous improvement in AHI may occur in some patients. Earlier development of snoring or stridor may predict rapid progression of SDB in MSA.