Systematic review of neuromuscular diurnal activity in restless legs syndrome

Purpose.The aim of this review was to systematically summarize the current literature on corticospinal excitation and muscle activity in restless legs syndrome (RLS) patients during daytime and diurnal activities. Three models of muscle activation in RLS directed this review: (i) evoked neuromuscular activation; (ii) sensory reflex responsiveness; (iii) voluntary muscle activation.Methods.A literature search was conducted in PubMed and Google Scholar, and 51 articles met the primary inclusion criteria. After a quality analysis, a total 13 articles were deemed of sufficient quality for data extraction.Results.Three studies on evoked neuromuscular activation demonstrated increased motor excitability associated with RLS. Sensory reflex responsiveness studies in RLS patients revealed increased reflex responsiveness, indicating increased spinal excitability and a possible dysfunction in afferent inhibition. Voluntary muscle activation studies showed both diurnal muscle electromyography abnormalities and an increased circadian variation in the musculature of the lower leg in RLS patients.Conclusions.Although a number of mechanisms have been evaluated increasing the understanding of RLS, few studies have evaluated RLS during daytime and diurnal muscle activity in patients with RLS. Furthermore, potential associations with the circadian rhythm have not been thoroughly investigated, nor have methodologies been combined. Future research should aim to establish differences in muscle activity of RLS patients and associate these differences with the duration and severity of symptoms. Suggestions for further studies are provided.