Correlates of periodic limb movements of sleep in the pediatric population.

Periodic limb movements of sleep are clinically underdiagnosed in children. Polysomnography is the most accurate diagnostic test. There is a paucity of information regarding polysomnography findings in children. We evaluated the prevalence and correlates of pediatric periodic limb movements detected by polysomnography. Periodic limb movements of sleep were identified in 77 of 982 polysomnograms, with a prevalence of 7.8% and male predominance (47 boys; 30 girls). Mean age was 9.4 +/- 4.2 years (1-19 years) (body mass index, 24.1 +/- 12.3). Mean sleep time was 395.4 +/- 73.4 minutes, of which rapid eye movement sleep constituted 16.6% +/- 6.7%, and slow-wave sleep, 22% +/- 10%. Sleep efficiency was 93.8 +/- 9.83, periodic limb movement index, 9.78 +/-7.9; periodic limb movement arousal, 4.5 +/- 8.4; arousal index, 27.8 +/- 12.4; and peak end-tidal CO(2), 48.9 +/- 10.5 mm Hg. Associated diagnoses included obstructive sleep apnea in 36 (46.8%), attention deficit hyperactivity disorder in 10 (13%), migraine in 7 (9.1%), seizures in 7 (9.1%), autism spectrum disorders in 5 (6.5%), and narcolepsy in 7 (9.1%). Serum ferritin was decreased (mean, 26.1 mug/L) in 29 (96.6%). Prospective studies may clarify the significance of incidental pediatric periodic limb movements in sleep detected on polysomnograms.