Sleep related myoclonus in rheumatic pain modulation disorder (fibrositis syndrome)

Thirty-three patients with rheumatic pain modulation disorder (RPMD) were divided into 2 groups: RPMD with sleep related myoclonus (RPMD-SM) (n = 12) and RPMD only (n = 21). Both groups showed chronic nonarticular musculoskeletal pain, fatigue, tender points, and nonrestorative sleep with alpha (7.5-11 Hz) EEG sleep anomaly. RPMD-SM patients were older, had later onset of illness, showed disrupted sleep with periodic involuntary leg movements that were related to fatigue, and alpha EEG sleep related to fatigue and pain.