Three patients with cancer who developed rapid-eye-movement sleep behavior disorder.

This article discusses the clinical significance of differentiating parasomnia, such as rapid-eye-movement (REM) sleep behavior disorder (RBD), from delirium in patients with advanced cancer. We describe three patients with advanced cancer who presented with aberrant behavior at night. All three patients developed violent behaviors when they were administered opioids and/or chemotherapy. Polysomnography (PSG) showed REM sleep with tonic electromyography. Previous treatment with neuroleptics had failed to improve their problematic behaviors. Diagnosis was made using criteria for REM behavior disorder of the International Classification of Sleep Disorders, 2nd edition, and PSG. Clonazepam (0.5 mg/day) was administered orally once at night. After treatment with clonazepam, aberrant and violent behaviors were improved. It should be noted that it is not rare for patients with advanced cancer to present with parasomnia, such as RBD, although organic brain syndrome, such as delirium, is more prevalent. Therefore, it is necessary to provide adequate assessment and treatment of aberrant behaviors in cancer patients.