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

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.

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.

In patients with ALS, the mean respiratory disturbance index (RDI) was 28.0/h, which was significantly higher than that in the controls (p < 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 (p = 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; p < 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 (p = 0.040).

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.