Sleep-related rhythmic movements and rhythmic movement disorder beyond early childhood.

Introduction: Sleep-related rhythmic movements (SRRMs) are common in young children and become less prevalent with increasing age. When SRRMs significantly interfere with sleep and/or affect daytime functioning, potentially resulting in injury, rhythmic movement disorder (SRRMD) is diagnosed.

Objective: The aim of our study was to assess clinical comorbidities, types of SRRMs, sleep stage/wakefulness distribution during night, and age-dependence of these parameters.

Material And Methods: In sum, 45 patients (age range 1-26 years, mean age 10.56 ± 6.4 years, 29 men) were clinically examined for SRRMs or SRRMD. Nocturnal polysomnography (PSG) was recorded in 38 patients. To evaluate clinical and sleep comorbidity, the cohort of 38 patients was divided according to age into four groups: (1) younger than 5 years (N = 7), (2) 5-9 years (N = 12), (3) 10-14 years (N = 11), and (4) ≥ 15 years (N = 8).

Results: A clear relationship between perinatal risk factors and developmental disorders (attention deficit hyperactivity disorder - ADHD, specific learning disability) was found which extended population prevalence at least five times. A total of 62 recordings were evaluated in 38 patients; SRRMs were found in PSG in 31 of 38 patients (82%). No age-dependent correlation between type of SRRMs and sleep stage/wakefulness distribution during the night was observed. However, when all recordings were correlated together, rolling stereotypes occurred more frequently in REM sleep, and rocking stereotypes in superficial NREM sleep.

Conclusion: Developmental disorders and perinatal risk factors were connected with SRRMs and SRRMD in children and young adults. Rolling movements were significantly associated with REM stage and rocking stereotypes with superficial NREM sleep, independent of age.