Sleep related rhythmic movement disorder: phenotypic characteristics and treatment response in a paediatric cohort.

OBJECTIVE: To describe phenotypic, polysomnographic characteristics, impact, and treatment response in children with sleep related rhythmic movement disorder (SR-RMD).

BACKGROUND: There is limited research on SR-RMD. We have developed a systematic clinical evaluation of children with SR-RMD to improve understanding and treatment.

METHODS: A retrospective chart review of 66 children at a UK tertiary hospital. Baseline assessment included validated screening questionnaires to study autism spectrum characteristics, general behaviour and sensory profile. A standardised questionnaire assessed impact on sleep quality and daytime wellbeing of child and family. Polysomnography data were collated.

RESULTS: Children were aged 0.9-16.3 years (78.8% male). 51.5% had a neurodevelopmental disorder, most commonly autism spectrum disorder. High rates of behavioural disturbance and sensory processing differences were reported, not confined to children with neurodevelopmental disorders. Parents reported concerns about risk of injury, loss of sleep and persistence into adulthood. Daytime wellbeing was affected in 72% of children and 75% of other family members. Only 31/48 children demonstrated rhythmic movements during video-polysomnography, occupying on average 6.1% of time in bed. Most clusters occurred in the settling period but also arose from N1, N2 and REM sleep and wake after sleep onset. Melatonin was prescribed to 52 children, all but one were extended-release preparations. 24/27 children with available data were reported to improve with melatonin.

CONCLUSIONS: SR-RMD places a significant burden on child and family wellbeing. Our novel findings of sensory processing differences in this population and parent reported therapeutic response to extended-release melatonin offer potential avenues for future research.