RESUMO
Objective To investigate the clinical features and the possible pathogenesis of rhythmic movement disorder (RMD) by analyzing 2 patients with RMD and reviewing the literature. Methods By using overnight polysomnogram (PSG) and sleeping video monitoring, the movement patterns, sleep architecture, and sleep quality of 2 patients who met the RMD diagnostic criteria were examined. Results Two male patients were 15-years old. The onset age of patient 1 was 3-years old, and patient 2 was 10-years old. All abnormal movements occurred in sleep, which presented with repetitive, stereotyping and rhythmical movements. Multiple patterns of abnormal sleeping movement were observed in 2 patients: head hypsokinesis, thoracic and waist hyperextension, and pendular movement of bilateral upper extremities. In the sitting position, the patient exhibited kneeling position, and fore-and-aft or lateral rhythmical swing of the upper body accompanied with head-banging. In the prone position, the patient behaved head backward hyperextension, and horizontal and fluctuating pendular movement of the body, which was just like the auto-erotic situation. In the lateral sleep position, the patient supported their head by using the right hand accompanied with fore-and-aft pendular movement of the head and the upper body. These symptoms mentioned above emerged immediately when the patient fell asleep, and continuously existed in all sleep period including non-rapid eye movement and rapid eye movement. All of the symptoms disappeared once the patient woke. The abnormal movement frequency was 0.1-2.0 Hz. In addition, the sleep architecture and quality were severely influenced by RMD in patient 2. Clonazepam might markedly ameliorate the symptoms and sleep quality. Conclusions Multiple abnormal movement patterns may exist in the RMD patients, and these abnormal movements could last during the whole sleep period. PSG and sleeping video monitoring should be undertaken for the suspected RMD patients, which are very useful for the definite diagnosis of RMD.