Nature and Science of Sleep (Apr 2021)
Commentary on the Paper by Wang et al: “Low Arousal Threshold: A Potential Bridge Between OSA and Periodic Limb Movements of Sleep” [Letter]
Abstract
Mauro Manconi,1– 3 Raffaele Ferri4 1Sleep Medicine Unit, Neurocenter of Southern Switzerland, Lugano, Italy; 2Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland; 3Department of Neurology, University Hospital, Inselspital, Bern, Switzerland; 4Sleep Research Centre, Oasi Research Institute - IRCCS, Troina, ItalyCorrespondence: Mauro Manconi Email [email protected] We have read with great interest the paper by Wang et al1 that shed a welcome spot of light on the intriguing and poorly addressed linkage between periodic limb movements (PLMS) and obstructive sleep apnea (OSA). With an elegant, despite retrospective, investigation, they tested the hypothesis that the OSA phenotype associated with low arousal threshold (ArTH) was a risk factor for the cooccurrence of OSA and PLMS. Once having rejected the null hypothesis, the authors confirmed their results in the independent large population of the MrOS study, and this is certainly a strength of the study. A second noteworthy methodological merit of the authors is to have used the new data-driven criteria to define the so-called respiratory-related leg movements (RRLM) proposed by the WASM taskforce.2 By using these criteria, all leg movements (LM) occurring within the time range from 2 s before to 10.25 s after the end of respiratory events were defined as RRLM. In addition, the authors repeated their analysis also using the standard AASM criteria (RRLM = LM overlapping or not separated by more than ±0.5 s from the end of the respiratory event).3 Since the recording of LM has become a standard procedure in accredited sleep labs, PLMS and RRLM are a frequent incidental finding and, besides their clinical significance possibly suggesting the existence of an underlying restless legs syndrome, the value of such motor components remains unclear as well as the option to treat them with dopamine agonists (DA). View the original paper by Wang and colleagues
