Pain and the Alpha‐Sleep Anomaly: A Mechanism of Sleep Disruption in Facioscapulohumeral Muscular Dystrophy

Objective To measure the presence of the alpha‐sleep anomaly in facioscapulohumeral muscular dystrophy ( FSHD ) and to evaluate the association between the sleep electroencephalogram ( EEG ) pattern and the presence of musculoskeletal pain. Design Cross‐sectional study. Setting Sleep laboratory. Subjects Fifty‐five consecutive adult FSHD patients, 26 women and 29 men, age 49.6 ± 15.1 years (range 18–76). Interventions Questionnaires and polysomnography. Outcome Measures Patients were asked to indicate if in the 3 months before the sleep study they presented persisting or recurring musculoskeletal pain. Patients who reported pain were asked to fill in the I talian version of the B rief P ain I nventory and the M c G ill P ain questionnaire, and a 101‐point visual analog scale ( VAS ) for pain intensity. Polysomnographic recordings were performed. EEG was analyzed by means of F ast F ourier T ransform. Four power spectra bands (δ 0–4  Hz , θ 4–8  Hz , α 8–14  Hz , β 14–32  Hz ) were computed. Sleep macrostructure parameters and alpha/delta EEG power ratio during non rapid eye movement ( NREM ) sleep were compared between patients with and without pain. Results Forty‐two patients in our sample reported chronic pain. VAS mean score was 55.2 ± 23.8 (range 10–100), pain rating index score was 13.8 ± 10.2, and present pain intensity was 2.5 ± 0.8. The statistical analysis documented an increased occurrence of the alpha and beta rhythms during NREM sleep in FSHD patients with pain. Significant correlations were observed between the alpha/delta power ratio during NREM sleep and pain measures. Conclusions Chronic musculoskeletal pain is frequent in FSHD patients, and it represents a major mechanism of sleep disruption.