High prevalence of periodic limb movements of sleep in children with Down syndrome

Study objectives: Increased periodic limb movements of sleep (PLMS), > 5 events/h, are present in 1.2% to 7.7% of healthy children and associated with hypertension, attention deficit, and hyperactivity. This study sought to determine the prevalence of elevated PLMS in a large cohort of children with Down syndrome (DS) and their correlation with OSA and ferritin levels.

Methods: Retrospective chart review of all children with DS ages 2 to 18 years in whom single baseline polysomnography (PSG) was performed at a pediatric hospital over 5 years.

Results: A total of 418 children met inclusion criteria. Three hundred fifty-six children (85%) were referred because of concerns about sleep-disordered breathing; 49 (12%) were referred for screening per American Academy of Pediatrics (AAP) guidelines; and 13 (3%) because of concerns about restless legs or periodic limb movement disorder. One hundred thirty-nine children (33.3%) had elevated PLMS; they were younger (6.3 years) than those without elevated PLMS (7.7 years). OSA was present in 176/418 (42.1%) children, including 13/49 (26.2%) asymptomatic children referred for screening PSG. Ferritin levels were only recorded in the charts of 65 of the children with elevated PLMS (46.7%); in 36 (55.4%) levels were < 50 ng/mL.

Conclusions: PLMS were increased in a substantial number of this large cohort of children with DS. Additional studies are necessary to assess utility of laboratory testing to predicting PLMS in similar, at-risk, populations. Screening PSG has value in identifying OSA in young, ostensibly asymptomatic children with DS. The prevalence of OSA increased with age in this cohort, unlike in typical children, requiring health care providers to remain vigilant for its emergence across the lifespan.