Pilot quantitative analyses of rem sleep without atonia in children and adolescents with rem sleep behavior disorder

Abstract

Introduction Growing evidence suggests that idiopathic REM sleep behavior disorder (RBD) may be a forme fruste of synucleinopathy neurodegeneration in older adults. The clinical significance of REM sleep without atonia (RSWA) and overt RBD in children and adolescents remains unclear. Furthermore, the lower age bound for occurrence of RSWA, the neurophysiologic substrate for RBD, is not well established. This pilot quantitative analysis of RSWA in pediatric patients with clinical RBD or RSWA – to our knowledge the first such data available in children – aims to determine the relationship between age, RBD symptoms, and RSWA. Materials and methods We analyzed phasic and tonic RSWA according to established methods in 12 RBD/RSWA patients and 12 age-gender matched controls with primary snoring who underwent polysomnography (PSG) at Mayo Clinic between 2008 and 2013, and reviewed medical records to determine RSWA or RBD diagnosis. We then measured phasic muscle activity durations and made group comparisons of phasic, tonic, and “any” muscle activity percentage densities as well as phasic muscle activity burst durations with non-parametric statistical tests. Multiple regression models were fit to explore potential associations between clinical and muscle activity dependent variables. Results Among the 12 RSWA/RBD cases, 7 were male, with a mean (range) age of 8.6 (1–17) years when PSG was performed. One RBD patient received clomipramine; no others were on medications associated with RSWA. Phasic and tonic densities were no different between cases and controls, although there appeared to be a subgroup of RSWA/RBD cases with higher phasic densities. Univariate regression analyses demonstrated that higher phasic density was associated with increasing age (p = 0.009 for chin and p = .004 for “any” muscle activity). Anterior tibialis phasic burst duration was significantly longer in the RSWA/RBD group compared to controls (p = 0.02), prolonged to a degree similar to that of adult RBD subjects. Multivariate regression demonstrated an independent association of anterior tibialis phasic burst duration with RBD/RSWA diagnosis, controlling for age. Conclusion In our pilot study, the earliest detectable manifestation of RSWA appears to be increased phasic burst duration in anterior tibialis. We also found that phasic muscle activity density increases with age in pediatric patients. We plan continued analysis in an expanded group of pediatric subjects to better elucidate the influences of age and RBD symptoms on quantitative RSWA metrics. Acknowledgements The project described was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health , through Grant No. 1 UL1 RR024150-01 . The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.