O020 Twitch in the Night: Periodic Limb Movements during Sleep in Children with Neuromuscular Disease or Cerebral Palsy

INTRODUCTION: Poor sleep is frequently reported in children with neuromuscular diseases (NMD) or cerebral palsy (CP) however ventilation is often the clinical focus. Periodic limb movements (PLMs) are frequently underdiagnosed in the paediatric population (prevalence of 5-8% in clinic-referred studies) and occur in up to 33% of children with Down syndrome. We assessed the prevalence of PLMs in children with NMD or CP. METHODS: Retrospective review of the first polysomnogram with leg electromyography in children with NMD (including Duchenne muscular dystrophy, myotonic dystrophy, and spinal muscular atrophy) or CP between 2005-2022. RESULTS: Leg electromyography was available in 238 children (124 NMD, 114 CP) with consent. 72 (30%) were female with a median age 9y (range 1-18y), BMI z-score 0.4 (-3.5 to 2.7), RDI 3.5/h (0-100/h) and arousal index of 11.7/h (1.3-65.6/h). Median PLM index was 0 (range 0-33/h) with %PLM arousals 0 (0-74%). The prevalence of elevated PLMs (>5/h) was 9.7% and 10.5% in the NMD and CP groups respectively, with median PLM arousals of 8.5% and 4.5% respectively. There were no differences in age or sex between those with or without elevated PLMs (p>0.05). DISCUSSION: Elevated PLM index occurred at a higher prevalence in children with NMD and CP than reported in the general paediatric population, though at lower rates than in Down syndrome. It is important that PLMs are not overlooked as identification and treatment may help improve sleep outcomes in this population. Further research is required to understand the pathophysiology of PLMs specifically in this population.