Periodic leg movements and sleep-disordered breathing in children

Summary Objective Children with OSAS (obstructive sleep apnea syndrome) have a restless sleep. Furthermore they show a changed daytime behavior comparable with attention deficit hyperactivity disorder (ADHD). We investigated the prevalence of periodic leg movements in sleep in OSAS patients to answer the question whether OSAS can be misinterpreted by insufficient diagnostics for example actigraphy alone. Methods 25 children who had no OSAS (controls) (age 3.1 to 14.3 years, median 7.3 years) were examined polysomnographically. 25 age-matched patients with clinically confirmed OSAS and an apnea/hypopnea index (AHI)≥5/h were investigated polysomnographically in one night before treatment (diagnostic night-baseline) and in one night with therapy. In the 3 groups the number of all leg movements (LM) and periodic leg movements (PLM) were counted in the time in bed as well as in the total sleep time (LMS/PLMS). Furthermore the number of LM and PLM was calculated in wakefulness, NREM and REM. The ratio of PLM to LM was calculated. Additionally we calculated, how frequently LMS and PLMS were accompanied by EEG-arousals. Results 92% of OSAS patients had an enhanced PLMS-Index > 5/h TST. OSAS patients without therapy had a significantly enhanced number of LMS (LMS: 19.2/h TST [qr=12.3]) and PLMS (11.8/h TST [qr=10.6]) in comparison to controls (LMS: 8.9/h TST [qr=2.4], PLMS: 2.3/h TST [qr=2.1]) and treated OSAS patients (LMS: 9.9/h TST [qr=4.7], PLMS: 3.7/h TST [qr=3.6]). Under therapy there was a significant diminution of LM and PLM in NREM and REM but not during wakefulness. Without therapy two thirds of all LMS were PLMS (66.3% [qr=16.4]) while in treated patients the total LMS included one third PLMS (39.6% [qr=32.9]) comparable with controls (28.4% [qr=15.9]). 90.1% [qr=18.9] of all PLMS in controls were accompanied by EEG-arousals but 61.0% [qr=23.9] in OSAS patients and 71.4% [qr=36.7] in treated OSAS patients. Conclusions OSAS patients in childhood have a PLMD by definition (PLMS>5 per hour TST, changed daytime behavior [2]) resolving by the therapy of sleep disturbed breathing. Because of the overlap of the symptoms sleep-disordered breathing should be considered in the differential diagnosis of children with PLMD, RLS (restless legs syndrome) and ADHD (attention deficit hyperactivity disorder). Different pathogenesis needs an appropriate therapeutic strategy.