A child with REM sleep disturbance.

An 8-year-old patient presented with history of snoring. He also had complaints of an upset stomach at night and talking during sleep. The child reportedly banged his head or rocked his body when going to sleep. He woke more than twice per night on average, and her had trouble falling back asleep. Epworth Sleepiness Scale score was 3. His teacher commented that he appeared sleepy during the day. His only medication was methylphenidate (Ritalin) for attention deficit hyperactivity disorder (ADHD). There was no history of developmental delay or mental retardation. Physical examination: Average built male child in no acute distress. Tonsils not enlarged. Respiratory, cardiac and neurological examination was normal. Tracings from the polysomnography are shown in Figures 1, ​22,​33,and ​44. Video clip from the polysomnography is available online at www.aasmnet.org/jcsm. Figure 1 Epoch length of 10 seconds Figure 2 Epoch length of 30 seconds Figure 3 Epoch length of 120 seconds Figure 4 Epoch length of 120 seconds (Different time period) Q: What is going on wth this patient in sleep? What is the diagnosis? A: Rhythmic movement disorder (RMD). The patient is in REM sleep. Note the total lack of the expected muscle atonia (leg EMG) during REM sleep. This is due to rhythmic movement disorder (RMD). The motion artifacts on EEG are also secondary to RMD. Diagnosis: Rhythmic movement disorder during REM sleep The child presented with RMD in the form of body rolling during each REM phase. The typical rapid eye movements during REM continued to be observed while the body thrashed around in a rhythmic pattern (clearly visible in the video clip). This behavior continued till the child shifted out of the REM phase, when it would suddenly end followed by a regular sleep pattern. Background EEG during these movements (see Figures) is predominantly low voltage mixed frequency with no alpha or delta predominant rhythm, differentiating it from wakefulness state. REM behavior disorder (RBD) is ruled out as there is no complex dream enactment; instead, the movements are rhythmic and repetitive. Also, there was no dream recall as is typically seen in RBD. Moreover, the patient had a complete neurological evaluation with a sleep and wake electroencephalogram (EEG) prior to the sleep study, showing no evidence of epilepsy. RMD represents an unusual variety of childhood parasomnias characterized by repetitive motion of the head, trunk, or extremities. RMD is defined by the International Classification of Sleep Disorders as a group of stereotyped, repetitive movements by the large muscles, usually of the head and neck, which typically occur immediately prior to sleep onset and are sustained into light sleep.1 However, RMD has been rarely reported during REM sleep, a sleep stage when typically the muscle activity is completely absent.2 It is typically observed in infants and young children presenting as head banging, head rolling, body rolling, or body rocking. The prevalence of RMD is high in infants younger than 9 months of age (up to 66%). It persists in approximately 30% of children at the age 4 years and usually disappears by 10 years of age.3 Very rarely do the symptoms persist into adolescence and adulthood.4,5 RMD is rarely described in REM sleep. Kohyama et al. reviewed 33 patients with RMD. Eighteen of the 33 RMD patients experienced episodes during REM sleep. Among the 18 patients who had episodes during REM sleep, 8 experienced the episodes exclusively during REM sleep.2 Most children who have RMD are healthy, although the condition may also be seen in association with autism and other developmental disabilities, especially if it persists in older children or adults. In one study, a strong association between RMD and ADHD was found in school-aged children. The authors proposed that pathogenetic mechanisms similar to those in ADHD are involved in RMD or that symptoms of ADHD may be secondary to RMD.6 For most affected children, RMD is a self-limited condition that does not require treatment. For children who suffer from particularly violent movements, use of protective padding in the crib or bed is recommended. Drug treatment of RMD has not been systematically studied in children, and a few isolated case reports address pharmacotherapy for this population. Clonazepam, oxazepam, and citalopram have been used with variable success.7 This disorder requires prompt and accurate recognition, as it may occasionally resemble nocturnal seizures and can cause injury to the patient.