Effects of Sleep-Related Disorders on the Prognosis of Amyotrophic Lateral Sclerosis

<b><i>Background/Objective:</i></b> In this study, we demonstrated the effects of obstructive sleep apnea syndrome (OSAS) on the prognosis of amyotrophic lateral sclerosis (ALS). However, the effects of sleep-related disorders other than breathing problems are still waiting to be delineated. <b><i>Methods:</i></b> In this longitudinal retrospective and prospective study, we investigated 73 patients with ALS compared to 20 healthy subjects, to determine sleep-related disorders and their impact on disease prognosis. <b><i>Results:</i></b> In patients with ALS, the mean respiratory disturbance index (RDI) was 28.0/h, which was significantly higher than that in the controls (<i>p</i> &#x3c; 0.001). OSAS was present in 67% of the patients, sleep-related hypoxemia was observed in 13.7% of the patients, and 5.4% had central sleep apnea syndrome. In patients with bulbar-onset disease, higher RDI was almost significantly associated with lower survival (<i>p</i> = 0.056). The mean index of periodic leg movements in sleep was significantly higher in patients with ALS (34.0 ± 19.9/h) than that in the controls (12.5 ± 15.5/h; <i>p</i> &#x3c; 0.001). Periodic leg movements disorder (PLMD) was diagnosed in 23 patients with ALS (31.5%); fragmentary myoclonus was present in 13.7% of patients, and REM-sleep behavior disorder was diagnosed in 4 patients (5.4%). The presence of PLMD in addition to OSAS was significantly associated with worse prognosis and poorer survival (<i>p</i> = 0.040). <b><i>Conclusions:</i></b> These findings emphasize that sleep-related disorders other than OSAS deserve attention in ALS. ALS is a catastrophic and frustrating disease for both patients and physicians; thus, the diagnosis and treatment of comorbid sleep disorders could improve the survival of patients with ALS.