Diagnosing rhythmic movement disorder with video-polysomnography.

We evaluated the utility of accurate clinical and electrophysiologic characterization in the diagnosis of the rhythmic movement disorder. Seven children with an age range of 1-12 years, referred for evaluation of relatively violent nocturnal behaviors, were clinically assessed during split-screen, video-polysomnographic monitoring sessions, as they experienced unusual nocturnus movements. Differential diagnoses included self-injurious waking behaviors, seizures, and parasomnias such as somnambulism (sleepwalking), pavor nocturnus (night terrors), and the rhythmic movement disorder (headbanging, bodyrocking, and legbanging). The character of movements, level of responsiveness, and electrophysiologic stage of sleep was determined during typical spells. In all the subjects experienced 37 periods of headbanging, bodyrocking, and legbanging that were strongly associated with stage 2 non-rapid eye movement sleep and K-complexes. The patients were unresponsive during and amnestic for the events. Because the differential for the rhythmic movement disorder includes a large number of disorders associated with abnormal and at times violent nocturnal movements, diagnosis can be greatly enhanced by documenting suspected nocturnal behaviors with thorough clinical assessment during split-screen, video-polysomnographic analysis.