Decreased nocturnal movements in patients with facioscapulohumeral muscular dystrophy

Reduced mobility during sleep characterizes a variety of movement disorders and neuromuscular diseases. Facioscapulohumeral muscular dystrophy (FSHD) is the third most common form of muscular dystrophy in the general population, and people with FSHD have poor sleep quality. The aims of the present study were to evaluate nocturnal motor activity in patients with FSHD by means of videopolysomnography and to verify whether activity was associated with modifications in sleep structure.

We enrolled 32 adult patients affected by genetically confirmed FSHD (18 women and 14 men, mean age 45.1 +/- 13.4 years) and 32 matched control subjects, (18 women and 14 men, mean age 45.5 +/- 11.4 years). Major body movements (MBM) were scored in videopolygraphic recordings in accordance with established criteria. An MBM index was calculated (number of MBM per hour of sleep).

The FSHD group showed a decrease in the MBM index (FSHD: 1.2 +/- 1.1; control subjects: 2.3 +/- 1.2, analysis of variance F = 13.672; p = 0.008). The sleep pattern of patients with FSHD, as compared with that of controls, was characterized by longer sleep latencies, shorter sleep durations, an increased percentage of wake during sleep, and a decreased percentage of rapid eye movement sleep. In the patient group, the MBM index was inversely correlated with severity of disease (Spearman test: r30 = -0.387; p < 0.05).

The present findings suggest that patients with FSHD have a reduced number of nocturnal movements, which is related to disease severity. Reduced movement in bed may contribute to the sleep modifications observed in these patients.