The Melanocortin and Endorphin Neuropeptides in Patients with Restless Legs Syndrome

OBJECTIVE

Based upon similarities between the urge to move and sensory discomfort of restless legs syndrome (RLS) and properties of melanocortin hormones, including their incitement of movement and hyperalgesia, we assessed plasma and cerebrospinal fluid (CSF) α-melanocyte-stimulating hormone (α-MSH) and β-endorphin in RLS patients and controls.

METHODS

Forty-two untreated moderate-to-severe RLS patients and 44 matched controls underwent venipuncture at 19:00, 20:30, and 22:00; 37 RLS and 36 controls had lumbar puncture at 21:30. CSF and plasma were analyzed for pro-opiomelanocortin (POMC), adrenocorticotropin hormone (ACTH), α-MSH, β-MSH, and β-endorphin by immunoassay. RLS severity was assessed by International RLS Study Group Severity Scale.

RESULTS

RLS participants were 52.7 ± 12.0 years old, 61.9% were women, 21.4% had painful RLS, and RLS severity was 24.8 ± 9.0. Controls had similar age and sex. Plasma ACTH, α-MSH, and β-endorphin were similar between groups. Plasma POMC was significantly greater in RLS than controls (17.0 ± 11.5 vs 12.7 ± 6.1fmol/ml, p = 0.048). CSF ACTH was similar between groups. CSF β-MSH was significantly higher in painful than nonpainful RLS or controls (48.2 ± 24.8 vs 32.1 ± 14.8 vs 32.6 ± 15.2pg/ml, analysis of variance [ANOVA] p = 0.03). CSF α-MSH was higher in RLS than controls (34.2 ± 40.9 vs 20.3 ± 11.0pg/ml, p = 0.062). CSF β-EDP was lowest in painful RLS, intermediate in nonpainful RLS, and highest in controls (8.0 ± 3.4 vs 10.8 ± 3.1 vs 12.3 ± 5.0pg/ml, ANOVA p = 0.049). The ratio of the sum of CSF α- and β-MSH to CSF β-endorphin was highest, intermediate, and lowest in painful RLS, nonpainful RLS, and controls (p = 0.007).

INTERPRETATION

CSF β-MSH is increased and CSF β-endorphin decreased in RLS patients with painful symptoms. ANN NEUROL 2024;95:688-699.

Restless legs syndrome in the dominant Parkinson's side related to subthalamic deep-brain stimulation

BACKGROUND

Restless legs syndrome (RLS) has an increased estimated prevalence in patients with Parkinson's disease (PS). RLS frequently mimics symptoms intrinsic to PD, such as motor restlessness, contributing to making its diagnosis challenging in this population. We report the case of a patient with new-onset RLS following subthalamic deep-brain stimulation (DBS-STN). We assessed symptoms using suggested immobilization test (SIT) with both DBS-STN activated and switched off.

CASE DESCRIPTION

A 59-year-old man with idiopathic PD developed disabling RLS following DBS-STN at age 58, with PD onset at 50 manifesting as left arm tremor. Despite improved motor symptoms during the month following surgery, the patient experienced left leg discomfort at rest, transiently alleviated by movements due to an irrepressible urge to move, and worsened at night. Symptoms had no temporal relationship with oral dopa-therapy and disappeared when DBS-STN was deactivated. A 1 h SIT assessed motor behavior with irrepressible urge to move, as well as sensory symptoms by visual analog scale. After 30 m DBS-STN was switched off followed by the appearance of tremor in the left arm while both motor and sensory symptoms of RLS disappeared in the left leg.

DISCUSSION

The mechanisms of DBS-STN's impact on RLS remain controversial. We hypothesize the DBS-STN to induce in our patient a hyperdopaminergic tone. DBS-induced and DBS-ameliorated RLS represent interesting conditions to further understand the pathophysiology of RLS. Moreover, the present observation suggests that SIT can be a valuable tool to assess RLS in PD patients before and after DBS-STN in future prospective studies.

The Effect of Hot and Cold Water Applications on Restless Legs Syndrome Complaints and Sleep Quality of Pregnant Women: A Randomized Controlled Study

Background

Pregnant women experience restless legs syndrome and intervention studies are needed to prevent this. This study evaluated the effect of hot and cold water applications on the severity of restless leg syndrome and sleep quality in pregnant women.

Methods

It is a randomized controlled trial. The subjects comprised 80 (hot water group = 26, cold water group = 27, control group = 27) pregnant women. Pregnant women in intervention groups applied hot or cold water to their legs before going to bed for seven days. The control group did not do any application other than routine care. The data were collected with the Restless Legs Syndrome Diagnostic Form, Personal Information Form, Restless Leg Syndrome Severity Grading Scale, The Pittsburgh Sleep Quality Index, Application Satisfaction Form, and Post-Application Follow-up Chart.

Results

While the Restless Legs Syndrome Severity Grading Scale and Pittsburgh Sleep Quality Index pre-test scores of the groups were similar (P > .05), the post-test scores were lower in the intervention groups than in the control group (P < .001). The effect of the applications started on the second day and the level of satisfaction with the application was similarly high in both groups (P < .05). During the follow-up, the syndrome severity scores of both the intervention groups were similar (P > .05), while the sleep quality of the cold group was better (P < .05) and most of the pregnant women did not need reapplication and they were satisfied with the application (P < .05).

Conclusion

These safe interventions reduced the severity of restless legs syndrome in pregnant women and improved the quality of their sleep. Nurses can use these applications in pregnancy care, which begin to show effect in as little as two days.

Changes in time structure of periodic leg movements during sleep in restless legs syndrome: Effects of sex and age

BACKGROUND

The objective of this study was to check the hypothesis that in women with restless legs syndrome (RLS) different changes occur in periodic leg movements during sleep (PLMS) during the post-menopausal period (using >50 years as a proxy) than in men of the same age.

METHODS

We recruited 36 untreated patients aged 18-50 years (19 men, median age 40 years, and 17 women, median age 37 years) while the remaining 67 were >50 years old (24 men, median age 66.6 years, and 43 women, median age 60.0 years). Leg movement activity during sleep was analyzed by means of an approach utilizing indexes especially suitable to assess leg movement periodicity.

RESULTS

No significant difference was seen between men in the two age groups; conversely, in women, a clear and significant increase in Periodicity Index was observed in the older group, along with a decrease in isolated leg movements. In women, a clear age-related enhancement of PLMS was found in the intermovement interval graphs, especially in the 16-22 s range, which was more evident than that observed in men. The results remained unchanged also when they were replicated by selecting only subjects aged 18-45 years vs. those aged >55 years.

CONCLUSIONS

Our findings indicate that assessing PLMS in women after menopause is clinically relevant because they are probably connected with the hormonal fluctuations of this period of life. Translationally, identifying and addressing PLMS in post-menopausal women is crucial for optimizing their sleep health and addressing potential health risks associated with sleep disturbances.

Sex-specific patterns of discomfort in patients with restless legs syndrome

STUDY OBJECTIVES

Sex differences in the prevalence of restless legs syndrome (RLS) have been reported, with a higher prevalence in women than in men. However, sex differences in clinical presentation remain unclear. We aimed to investigate the phenotypic differences in patients with RLS between sexes by comparing clinical presentations, iron status, polysomnographic parameters, and treatment.

METHODS

We retrospectively evaluated 614 patients (225 men, 389 women) diagnosed with RLS. To enhance the robustness of the study, an age-matched control group of 179 men and 286 women without sleep disorders was also included. Information on demographics and sleep-related questionnaires were collected. Iron status was evaluated using blood samples, and polysomnography was performed to evaluate periodic leg movements and comorbid sleep disorders.

RESULTS

Our analysis revealed no sex difference in the severity of RLS but a difference in the pattern of symptoms. Women had more frequent symptoms of pain and awakening during sleep, while men had more common motor symptoms (both self-reported symptoms and periodic leg movement on polysomnography). Women with RLS also had lower iron parameters and received more frequent iron supplementation therapy than men. In contrast to women with RLS, who presented higher sleep disturbances and depressive mood, men with RLS had a higher risk of comorbidities such as hypertension and cardiovascular disease. These sex differences were notably more pronounced than in the control group.

CONCLUSIONS

This study suggests that sex differences exist in RLS phenotypes, and clinicians should consider these differences for treatment.

CITATION

Kim J, Kim JR, Park HR, Joo EY. Sex-specific patterns of discomfort in patients with restless legs syndrome. J Clin Sleep Med. 2024;20(2):253-259.

Proteomic insights into the pathophysiology of periodic limb movements and restless legs syndrome

OBJECTIVES

We used a high-throughput assay of 5000 plasma proteins to identify biomarkers associated with periodic limb movements (PLM) and restless legs syndrome (RLS) in adults.

METHODS

Participants (n = 1410) of the Stanford Technology Analytics and Genomics in Sleep (STAGES) study had blood collected, completed a sleep questionnaire, and underwent overnight polysomnography with the scoring of PLMs. An aptamer-based array (SomaScan) was used to quantify 5000 proteins in plasma. A second cohort (n = 697) that had serum assayed using a previous iteration of SomaScan (1300 proteins) was used for replication and in a combined analysis (n = 2107). A 5% false discovery rate was used to assess significance.

RESULTS

Multivariate analyses in STAGES identified 68 proteins associated with the PLM index after correction for multiple testing (ie, base model). Most significantly decreased proteins were iron-related and included Hepcidin (LEAP-1), Ferritin, and Ferritin light chain. Most significantly increased proteins included RANTES, Cathepsin A, and SULT 1A3. Of 68 proteins significant in the base model, 17 were present in the 1300 panel, and 15 of 17 were replicated. The most significant proteins in the combined model were Hepcidin (LEAP-1), Cathepsin A, Ferritin, and RANTES. Exploration of proteins in RLS versus non-RLS identified Cathepsin Z, Heme oxygenase 2 (HO-2), Interleukin-17A (upregulated in the combined cohort), and Megalin (upregulated in STAGES only) although results were less significant than for proteins associated with PLM index.

CONCLUSIONS

These results confirm the association of PLM with low iron status and suggest the involvement of catabolic enzymes in PLM/RLS.

Daytime impulsiveness, attention, and learning in the restless legs syndrome

INTRODUCTION

Restless legs syndrome (RLS) is a sensorimotor condition characterized by disturbing sensations and the desire to move, often localized in the legs. Cognitive changes and impulsivity can be present in RLS, although the potential effect of commonly co-occurring attention-deficit/hyperactivity disorders (ADHD) or dopamine agonist (DA) use on these are unclear.

METHOD

Twenty-three RLS patients and 22 healthy controls were included. Rey Auditory Verbal Learning Test (RAVLT), Continuous Performance Test (CPT), Beck Depression Inventory (BDI), Epworth Sleepiness Scale (ESS), State and Trait Anxiety Inventory (STAI), and Adult Attention Deficit Self-Evaluation Scale (ASRS) were administered. Performance was compared between RLS patients and controls accounting for the presence of attention-deficit/hyperactivity disorder (ADHD) and DA use.

RESULTS

Age, education, BDI, ESS, STAI, and ASRS scores were similar for control and RLS groups. Control and RLS groups performed similarly on auditory verbal learning and general attention tests. In the CPT, commission error was significantly higher and response time was significantly shorter in the RLS group compared to controls (p = .014 and p = .010, respectively). These significant differences persisted after adjusting for ADHD and DA usage.

CONCLUSION

In this study, RLS patients were more impulsive than the healthy individuals independent of ADHD and DA use. However, learning and attention performances of the patients are not affected.

Structural Relationships Between Behavioral Problems, Sensory Processing Traits, and Sleep Among Preschoolers

IMPORTANCE

An association between sensory processing difficulties and behavioral problems among children has been reported in previous studies. Sleep problems among children can lead to both externalizing and internalizing behavioral problems. However, the relationships between sensory processing and sleep among children are not well understood.

OBJECTIVE

To develop a structural causal model (SCM) predicated on the hypothesis that sensory processing difficulties and sleep problems are closely related among preschoolers and may contribute to behavioral issues.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 168 children ages 3-5 yr who were enrolled in a preschool or an accredited kindergarten (four facilities in total) in a Japanese prefecture participated in the analysis.

OUTCOMES AND MEASURES

After gaining the cooperation of educators, we distributed the following items to the children's parents: an informed consent form, the Short Sensory Profile-Japanese version (SSP-J), the Japanese Sleep Questionnaire for Preschoolers (JSQ-P), and the Child Behavior Checklist for Ages 1.5-5. Through factor analysis of the SSP-J and the JSQ-P, we identified common factors. We developed an SCM using structural equation modeling.

RESULTS

Four factors were identified by factor analysis: attention deficit, sensory sensitivity, sleep problems, and restless legs syndrome symptoms. The final structural equation modeling analysis had an acceptable goodness of fit (goodness-of-fit index = .862; root-mean-square error of approximation = .087).

CONCLUSIONS AND RELEVANCE

The model suggests that sensory sensitivity and sleep difficulties may contribute to behavioral issues among preschoolers. Plain-Language Summary: The results of this study suggest that relationships exist between behavioral problems, sensory processing, and sleep among preschoolers. The authors developed a model that identified four common factors that contribute to behavioral issues among preschoolers: attention deficit, sensory sensitivity, sleep problems, and restless legs syndrome symptoms. Children's behavioral problems are an important consideration for occupational therapy practitioners working with preschoolers. Sensory processing and sleep must be accurately evaluated to address preschoolers' behavioral issues.

Long-term dopamine agonist treatment fails to restore altered central sensory processing in restless legs syndrome: Evidence from current perception threshold measurements

OBJECTIVES

Although some studies have examined the impact of short-term dopamine agonist treatment on altered central sensory processing in patients with restless legs syndrome (RLS), there is a scarcity of research investigating the effect of long-term treatment with these drugs. The aim of this study is to investigate the long-term impact of dopamine agonist treatment on altered central sensory processing in RLS patients using current perception threshold (CPT) testing.

METHODS

We conducted a study of 24 RLS patients, measuring their CPT values before and after dopamine agonist treatment for at least 2 months. Patients were classified as responders or non-responders based on their decrease in International Restless Legs Syndrome (IRLS) score. Clinical parameters were collected and compared pre- and post-treatment.

RESULTS

The mean duration of treatment with dopamine agonist was 13.6 ± 11.0 months. Our results showed that dopamine agonist treatment significantly improved clinical parameters, including the IRLS score, Visual Analogue Scale, and RLS Quality of Life questionnaire. However, CPT values did not show significant changes for all stimulus frequencies after treatment. Furthermore, we did not find any difference in CPT values before and after treatment in both responders and non-responders.

CONCLUSIONS

Our study demonstrated that long-term treatment with dopamine agonists effectively reduces RLS symptoms, but does not reverse the altered central sensory processing observed on CPT testing in RLS patients. These results support the notion that the pathophysiology of RLS is multifactorial and not solely driven by dopaminergic dysfunction.

Redefining the role of the cerebellum in restless legs syndrome

OBJECTIVES

We aimed to investigate alterations in cerebellar volume and the intrinsic cerebellar network in patients with restless legs syndrome (RLS).

METHODS

We recruited 69 patients with RLS and 50 healthy controls who underwent brain magnetic resonance imaging (MRI), including three-dimensional T1-weighted imaging. The total cerebellar volume and cerebellar volume subdivisions were analyzed through automatic cerebellum anatomical parcellation using U-Net with locally constrained optimization program. The intrinsic cerebellar network was calculated through brain analysis using a graph theory program based on the cerebellar volume subdivisions. The cerebellar volumes and intrinsic cerebellar networks were compared between patients with RLS and healthy controls.

RESULTS

The cerebellar volume and subdivisions in patients with RLS did not show significant differences compared to those in healthy controls. However, significant alterations were observed in the intrinsic cerebellar network of patients with RLS. Increased mean clustering coefficient (0.185 vs. 0.114; p = 0.047) and small-worldness index (0.927 vs. 0.800; p = 0.047) were observed in patients with RLS. Additionally, total cerebellar volume was negatively correlated with the Pittsburgh Sleep Quality Index (r = -0.398; p = 0.020) and Insomnia Severity Index (ISI; r = -0.396; p = 0.011). Negative correlations were additionally observed between the right X lobule volume and the International Restless Legs Syndrome Severity Scale (r = -0.425; p = 0.008) and between the vermis VIII volume and ISI score (r = -0.399; p = 0.011).

CONCLUSION

We demonstrated alterations in the intrinsic cerebellar network in patients with RLS compared with healthy controls, showing increased connectivity with increased segregation in patients with RLS. This suggests a potential role of the cerebellum in RLS pathophysiology.

Evaluation of the relationship between idiopathic restless legs syndrome and serum hepcidin levels

INTRODUCTION

The relationship between restless legs syndrome (RLS) and iron deficiency is a well-known topic. However, the etiology of the disease has not been determined. As the central iron deficiency is the most critical biological abnormality for RLS, we planned a study examining the relationship between RLS and hepcidin, which is the only regulatory hormone of iron metabolism known so far.

METHODS

International Restless Legs Syndrome Study Group diagnostic criteria (2014) were taken as a basis. A total of 40 RLS patients and 40 healthy controls were included in the study. To avoid the potential variables that might cause secondary RLS, all the participants were asked to provide hemogram, ferritin, iron, thyroid function tests, and sedimentation analysis. The hepcidin levels were measured with a Human Hepcidin (Hepc 25) ELISA kit (MyBioSource).

RESULTS

The statistically significant results of our analysis show that the red blood cell count, the neutrophil count, the percentage of lymphocytes and neutrophils, and, more distinctively, hepcidin levels were higher in RLS patients in comparison with the control group.

CONCLUSION

In this study, no differences were found in iron and ferritin values. High levels of hepcidin, the main regulator of iron metabolism, in those with primary RLS support the possibility that hepcidin may play a role in the pathogenesis of RLS. We think that larger studies on this subject can give clearer ideas.

An analysis of YouTube videos about restless leg syndrome: Choosing the right guide

Individuals often resort to YouTube as a means of accessing insights into their medical conditions and potential avenues for treatment. Among prevalent and incapacitating afflictions within the general populace, restless leg syndrome assumes significance. The focal objective of this investigation is to scrutinize the caliber inherent in videos pertaining to restless leg syndrome disseminated via the YouTube platform. The sorting of videos was accomplished by gauging their pertinence subsequent to conducting a search for "restless leg syndrome" on YouTube, specifically on the 20th of August, 2023. The evaluation encompassed videos curated from the selection of the top 50 English language videos deemed most relevant. The review process entailed the comprehensive assessment of relevance and content by 2 distinct medical professionals operating independently. Furthermore, pertinent descriptive attributes of each video, such as upload date, view count, likes, dislikes, and comments, were meticulously documented within the dataset. To ascertain video quality, the DISCERN Score, global quality score, and Journal of the American Medical Association rating scales were employed as evaluative tools. Significant statistical disparities were observed in terms of DISCERN scores between videos uploaded by medical doctors and those uploaded by individuals without medical qualifications (P < .001). Correspondingly, upon comparing the 2 aforementioned groups, videos uploaded by healthcare professionals exhibited statistically superior quality scores in both the Journal of the American Medical Association and global quality score assessments (P < .001 for both comparisons). The informational quality regarding restless leg syndrome on YouTube presents a spectrum of variability. Notably, videos that offer valuable insights, as well as those that could potentially mislead viewers, do not display discernible variations in terms of their viewership and popularity. For patients seeking reliable information, a useful and safe approach involves favoring videos uploaded by medical professionals. It is imperative to prioritize the professional identity of the content uploader rather than being swayed by the video's popularity or the quantity of comments it has amassed.

Cerebellum drives functional dysfunctions in restless leg syndrome

OBJECTIVE

Restless legs syndrome (RLS) has serious effects on patients' sleep quality, physical and mental health. However, the pathophysiological mechanisms of RLS remain unclear. This study utilized both static and dynamic functional activity and connectivity analyses approaches as well as effective connectivity analysis to reveal the neurophysiological basis of RLS.

METHODS

The resting-state functional MRI (rs-fMRI) data from 32 patients with RLS and 33 age-, and gender-matched healthy control (HC) were collected. Dynamic and static amplitude of low frequency fluctuation (ALFF), functional connectivity (FC), and Granger causality analysis (GCA) were employed to reveal the abnormal functional activities and couplings in patients with RLS.

RESULTS

RLS patients showed over-activities in left parahippocampus and right cerebellum, hyper-connectivities of right cerebellum with left basal ganglia, left postcentral gyrus and right precentral gyrus, and enhanced effective connectivity from right cerebellum to left postcentral gyrus compared to HC.

CONCLUSIONS

Abnormal cerebellum-basal ganglia-sensorimotor cortex circuit may be the underlying neuropathological basis of RLS. Our findings highlight the important role of right cerebellum in the onset of RLS and suggest right cerebellum may be a potential target for precision therapy.

Defect of the Endogenous Inhibitory Pain System in Idiopathic Restless Legs Syndrome: A Laser Evoked Potentials Study

BACKGROUND

Restless legs syndrome (RLS) is a complex sensorimotor disorder. Symptoms worsen toward evening and at rest and are temporarily relieved by movement. Symptoms are perceived as painful in up to 45% of cases, and nociception system may be involved.

OBJECTIVES

To assess the descending diffuse noxious inhibitory control in RLS patients.

METHODS

Twenty-one RLS patients and twenty age and sex-matched healthy controls (HC) underwent a conditioned pain modulation protocol. Cutaneous heat stimuli were delivered via laser evoked potentials (LEPs) on the dorsum of the right hand (UL) and foot (LL). N2 and P2 latencies, N2/P2 amplitude and pain ratings (NRS) were recorded before (baseline), during, and after a heterotopic noxious conditioning stimulation (HNCS) application. The baseline/HNCS ratio was calculated for both UL and LL.

RESULTS

N2 and P2 latencies did not vary between groups at each condition and limbs. Both groups showed a physiological N2/P2 amplitude and NRS reduction during the HNCS condition in UL and LL in comparison to baseline and post conditions (all, P < 0.003). Between-groups comparisons revealed a significant lower amplitude reduction in RLS at the N2/P2 amplitude during the HNCS condition only for LL (RLS, 13.6 μV; HC, 10.1 μV; P = 0.004). Such result was confirmed by the significant difference at the ratio (RLS, 69%, HC, 52.5%; P = 0.038).

CONCLUSIONS

The lower physiological reduction during the HNCS condition at LL in RLS patients suggests a defect in the endogenous inhibitory pain system. Further studies should clarify the causal link of this finding, also investigating the circadian modulation of this paradigm. © 2023 International Parkinson and Movement Disorder Society.

Comparative assessment of choroidal thickness and choroidal vascularity index in patients with restless legs syndrome

BACKGROUND

Increased sympathetic activity has been emphasized in the pathophysiology of restless legs syndrome (RLS). This study aims to evaluate the choroidal thickness (CT) and choroidal vascularity index (CVI) values of individuals with RLS.

METHODS

A total of 60 volunteers, 30 individuals with RLS and 30 healthy individuals, were included in the study. The central macular thickness, subfoveal CT, and the CTs 1000 μm away from the fovea in the temporal and nasal regions were measured by optical coherence tomography. Total choroidal area (TCA), luminal area (LA) and stromal area (SA) were calculated using the binarization method. CVI was calculated as the ratio of lumen area to total choroidal area (LA/TCA).

RESULTS

There was no significant difference between the participants in terms of age, gender, spherical equivalent, intraocular pressure, and axial length (p>0.05). The mean LA/SA was 1.56%±0.05 in RLS group and 1.99%±0.28 in the control group. The mean CVI was 0.64%±0.02% in RLS group and 0.66%±0.03 in the control group. There was no significant difference between the groups in terms of CT, TCA and LA values. There were significant differences between the groups in SA, LA/SA and CVI values (p = 0.017, p<0.001, and p = 0.004, respectively).

CONCLUSION

SA values were significantly higher in RLS group than in control group. The LA/SA and CVI values were significantly lower in RLS group than in control group. These findings suggests that there is vascular narrowing due to sympathetic overactivity in RLS patients.

Pediatric sleep: current knowledge, gaps, and opportunities for the future

This White Paper addresses the current gaps in knowledge, as well as opportunities for future studies in pediatric sleep. The Sleep Research Society's Pipeline Development Committee assembled a panel of experts tasked to provide information to those interested in learning more about the field of pediatric sleep, including trainees. We cover the scope of pediatric sleep, including epidemiological studies and the development of sleep and circadian rhythms in early childhood and adolescence. Additionally, we discuss current knowledge of insufficient sleep and circadian disruption, addressing the neuropsychological impact (affective functioning) and cardiometabolic consequences. A significant portion of this White Paper explores pediatric sleep disorders (including circadian rhythm disorders, insomnia, restless leg and periodic limb movement disorder, narcolepsy, and sleep apnea), as well as sleep and neurodevelopment disorders (e.g. autism and attention deficit hyperactivity disorder). Finally, we end with a discussion on sleep and public health policy. Although we have made strides in our knowledge of pediatric sleep, it is imperative that we address the gaps to the best of our knowledge and the pitfalls of our methodologies. For example, more work needs to be done to assess pediatric sleep using objective methodologies (i.e. actigraphy and polysomnography), to explore sleep disparities, to improve accessibility to evidence-based treatments, and to identify potential risks and protective markers of disorders in children. Expanding trainee exposure to pediatric sleep and elucidating future directions for study will significantly improve the future of the field.

Bibliometric analyses of publications in the field of restless legs syndrome

PURPOSE

Restless Legs Syndrome (RLS) is a chronic neurological disorder and the incidence of RLS is a more common disease than known is accepted. This study was performed to identify and analyze the characteristics of RLS-related articles published from 2001 to 2020 using bibliometric analyses.

METHODS

RLS-related articles published from 2001 to 2020 were retrieved from the Web of Science Core Collection database with predefined search terms. VOSviewer software was used to visualize various bibliographic coupling networks on data. The top 10 lists (about organizations, papers, journals, most commonly cited articles, authors, countries, and keywords) extracted from 2001 to 2020 were also analyzed.

RESULTS

A total of 2311 articles were included and the total number of publications from 2001 to 2020 was increased by 5.02-fold. The highest number of RLS publications (n = 171) since 2001 was observed in 2020. The United States is contributed the highest number of RLS-related publications (34.53%). The top productive journal was Sleep Medicine and the most prominent organization was Johns Hopkins University. In the list of top 10 authors, Allen RP was the first author.

CONCLUSIONS

This study is the first bibliometric analysis that provides a general perspective on the RLS from 2001 to 2020 and may be useful as a guide for further research in this field.

Polysomnographic features of idiopathic restless legs syndrome: a systematic review and meta-analysis of 13 sleep parameters and 23 leg movement parameters

STUDY OBJECTIVES

This study aims to explore the polysomnographically measured sleep and leg movement differences between idiopathic restless legs syndrome (RLS) patients and healthy controls.

METHODS

An electronic literature search was conducted in EMBASE, MEDLINE, all EBM databases, CINAHL, and PsycINFO. Only observational case-control studies were included in the meta-analysis. The differences in 13 sleep parameters and 23 leg movement parameters between RLS patients and healthy controls were explored.

RESULTS

Thirty-eight studies were identified for systematic review, 31 of which were used for meta-analysis. Meta-analyses revealed significant reductions in total sleep time, sleep efficiency, stage N2 and rapid eye movement (REM) sleep percentages, and increases in wake time after sleep onset, stage shifts per hour, stage N1 percentage, REM latency, arousal index, and apnea-hypopnea index. Some leg movement parameters, such as periodic limb movement during sleep (PLMS) index, PLMS sequence duration, number of PLMS sequence, and periodicity index, were higher in RLS patients compared with healthy controls. Further, our meta-analysis revealed a higher PLMS index during non-REM sleep compared with that during REM sleep.

CONCLUSIONS

RLS patients manifest a lightening of sleep, increased sleep fragmentation, and greater sleep-related breathing disruption and limb movements during sleep relative to healthy normal individuals. The distributions of PLMS during a night's sleep may provide more information to clarify the specific characteristics of leg movements in RLS. PLMS in RLS are concentrated in non-REM sleep. The periodicity index may be a more sensitive and specific marker of RLS than the PLMS index.

CITATION

Zhang H, Zhang Y, Ren R, et al. Polysomnographic features of idiopathic restless legs syndrome: a systematic review and meta-analysis of 13 sleep parameters and 23 leg movement parameters. J Clin Sleep Med. 2022;18(11):2561-2575.

Brain-iron deficiency models of restless legs syndrome

Restless legs syndrome (RLS) is a common sensorimotor disorder for which two main pathological elements are fairly well accepted: Brain iron deficiency (BID) and an altered dopaminergic system. The ability to better understand the causal and consequential factors related to these two pathological elements, would hopefully lead to the development of better therapeutic strategies for treating, if not curing, this disease. The current understanding of the relationship between these two elements is that BID leads to some alterations in neurotransmitters and subsequent changes in the dopaminergic system. Therefore, rodent models based on diet-induced BID, provide a biological substrate to understand the consequences of BID on dopaminergic pathway and on alternative pathways that may be involved. In this review, we present the current research on dopaminergic changes found in RLS subjects and compare that to what is seen in the BID rodent model to provide a validation of the BID rodent model. We also demonstrate the ability of the BID model to predict changes in other neurotransmitter systems and how that has led to new treatment options. Finally, we will present arguments for the utility of recombinant inbred mouse strains that demonstrate natural variation in brain iron, to explore the genetic basis of altered brain iron homeostasis as a model to understand why in idiopathic RLS there can exist a BID despite normal peripheral iron store. This review is the first to draw on 25 years of human and basic research into the pathophysiology of RLS to provide strong supportive data as to the validity of BID model as an important translational model of the disease. As we will demonstrate here, not only does the BID model closely and accurately mimic what we see in the dopaminergic system of RLS, it is the first model to identify alternative systems from which new treatments have recently been developed.

Brain Iron Deficiency Changes the Stoichiometry of Adenosine Receptor Subtypes in Cortico-Striatal Terminals: Implications for Restless Legs Syndrome

Brain iron deficiency (BID) constitutes a primary pathophysiological mechanism in restless legs syndrome (RLS). BID in rodents has been widely used as an animal model of RLS, since it recapitulates key neurochemical changes reported in RLS patients and shows an RLS-like behavioral phenotype. Previous studies with the BID-rodent model of RLS demonstrated increased sensitivity of cortical pyramidal cells to release glutamate from their striatal nerve terminals driving striatal circuits, a correlative finding of the cortical motor hyperexcitability of RLS patients. It was also found that BID in rodents leads to changes in the adenosinergic system, a downregulation of the inhibitory adenosine A₁ receptors (A₁Rs) and upregulation of the excitatory adenosine A_2A receptors (A_2ARs). It was then hypothesized, but not proven, that the BID-induced increased sensitivity of cortico-striatal glutamatergic terminals could be induced by a change in A₁R/A_2AR stoichiometry in favor of A_2ARs. Here, we used a newly developed FACS-based synaptometric analysis to compare the relative abundance on A₁Rs and A_2ARs in cortico-striatal and thalamo-striatal glutamatergic terminals (labeled with vesicular glutamate transporters VGLUT1 and VGLUT2, respectively) of control and BID rats. It could be demonstrated that BID (determined by measuring transferrin receptor density in the brain) is associated with a selective decrease in the A₁R/A_2AR ratio in VGLUT1 positive-striatal terminals.

Sleep quality and related factors including restless leg syndrome in medical students and residents in a Turkish university

PURPOSE

The aim was to determine sleep quality and related factors including restless leg syndrome in the 6th year medical students and medical residents in Pamukkale University, Faculty of Medicine, Denizli, Turkey.

METHODS

The data collection phase of this cross-sectional study was completed between November 1st and December 31st, 2019, with a questionnaire including 59 items. Three hundred forty-one medical students and residents participated in the study. The Pittsburgh Sleep Quality Index was used to determine the participants' sleep quality. The International Restless Legs Syndrome Study Group Diagnostic Criteria and the Restless Leg Syndrome Rating Scale were used for the diagnosis and for determining the seriousness of restless leg syndrome, respectively.

RESULTS

The mean age (SD ±) was 26.6 ± 3.2. Men (50%) and medical residents (59%) constituted the majority. Most of the participants (70%) had poor sleep quality, and 9% had restless leg syndrome. Despite losing their significance in multivariable analysis, a relationship existed between restless leg syndrome and sleep quality in bivariate comparisons (p = 0.04). According to the multiple variable analysis, age (p = 0.008), female gender (p = 0.04), insufficient income (p = 0.009), being on-medication (p = 0.007), being a current smoker (p = 0.01), not sleeping at the usual time (p = 0.04), and listening to music before sleeping (p = 0.03) were identified as independent risk factors for poor sleep quality.

CONCLUSIONS

The prevalence of poor sleep quality and restless leg syndrome are high in the 6th year medical students and residents. Necessary measures should be taken to reduce the effect of negative conditions on these vulnerable groups.

Sleep Disorders in Mitochondrial Diseases

PURPOSE OF REVIEW

We aim to summarize the sleep disorders reported in patients affected by primary mitochondrial dysfunctions and describe the association with their clinical and molecular characteristics.

RECENT FINDINGS

Sleep complaints are prevalent in mitochondrial disorders. Sleep-disordered breathing is the main sleep disorder reported in mitochondrial diseases. OSA and CSA are, respectively, more frequently associated with patients characterized by the prevalent involvement of the skeletal muscle and the predominant involvement of the central nervous system. Other sleep disorders, such as restless legs syndrome, have been rarely described. Sleep disorders are frequently associated with primary mitochondrial disorders, and the clinical phenotypes affect the type of sleep disturbance associated with the mitochondrial dysfunction. A polysomnographic study should be performed in every subject with this neurogenetic disorder both at diagnosis and during follow-up for the numerous adverse clinical outcomes associated with sleep disorders and the frailty of mitochondrial patients.

Zinc and Magnesium Levels of Pregnant Women with Restless Leg Syndrome and Their Relationship with Anxiety: A Case-Control Study

Restless leg syndrome (RLS) is a multifactorial movement disorder, and pregnancy is seen as a risk factor. This study aims to determine the clinical and psychiatric causes of RLS with a case-control study. The hemogram, biochemistry data, thyroid function tests, and serum element levels of healthy pregnant women (n = 134) and pregnant women diagnosed with RLS (n = 119) were compared. Total Ca, Mg, K, and Na concentrations were measured with an inductively coupled plasma optical emission spectrometry (ICP-OES), and an atomic absorption spectrophotometer was used to measure total concentrations of Zn in all samples. The Beck Anxiety Inventory (BAI), the Beck Depression Inventory (BDI), and the Pittsburg Sleep Quality Index (PSQI) scores were also compared in both groups. Sonographic measurements showed that the fetal biparietal diameter and femur lengths were higher in the RLS group (p = 0.001, p = 0.048, respectively), and abortion history was higher in the RLS group (p = 0.016). Magnesium and zinc levels were lower (p < 0.001 for both) and BAI and PSQI scores were higher (p < 0.001 for both) in the RLS group, and there was no difference between the BDI (p = 0.269) scores. A statistically significant relationship was detected between the BAI and RLS scores in the control and RLS groups (p < 0.001 for both). This is the first study to show that magnesium and zinc deficiency may play a role in the etiology of RLS during pregnancy; the results also showed adverse perinatal outcomes such as high miscarriage.

Effects of insomnia and restless legs syndrome on sleep arterial blood pressure: A systematic review and meta-analysis

Hypertension and blunted blood pressure (BP) dipping during nighttime sleep are associated with increased cardiovascular risk. Chronic insomnia and restless legs syndrome (RLS) may affect the 24-h BP profile. We systematically reviewed the association of insomnia and RLS with BP values during nighttime sleep and the relative BP dipping pattern. We searched relevant articles in any language with selection criteria including enrolment of subjects with insomnia or RLS and with obstructive sleep apnea comorbidity assessment. Of the 872 studies originally retrieved, seven were selected. Four studies enrolled subjects with insomnia. One study relied on sleep diaries to classify nighttime sleep BP, whereas three relied only on clock time. At meta-analysis, subjects with insomnia displayed an attenuated dipping of systolic BP (-2.00%; 95% confidence interval (CI): -3.61 - -0.39%) and diastolic BP (-1.58%; 95% CI: -2.66 ̶ -0.49%) during nighttime sleep compared to controls. Three studies enrolled subjects with RLS. One study relied on polysomnography to classify nighttime sleep BP, whereas two relied only on clock time. Subjects with RLS showed increases in nighttime sleep systolic BP (5.61 mm Hg, 95% CI 0.13̶-11.09 mm Hg) compared to controls. In conclusion, the limited available data suggest that insomnia and RLS are both associated with altered BP control during nighttime sleep. There is need for more clinical studies to confirm these findings, specifically focusing on measurements of BP during objectively defined sleep, on causal roles of leg movements during sleep and alterations in sleep architecture, and on implications for cardiovascular risk. PROSPERO ACKNOWLEDGEMENT OF NUMBER: CRD42020217947.

Restless sleep disorder in children with attention-deficit/hyperactivity disorder

STUDY OBJECTIVES

Restless sleep is a very common parental complaint in children with attention-deficit/hyperactivity disorder (ADHD), but restless sleep has been seen in association with other comorbidities such as restless legs syndrome and obstructive sleep apnea. Restless sleep disorder (RSD) needs to be identified from other disorders when evaluating children with ADHD. In this study we aim to identify the prevalence of RSD in children with ADHD referred to our sleep center.

METHODS

This is a retrospective study of children with ADHD who underwent polysomnography. The following diagnostic and descriptive data were obtained for each patient: age, sex, presence/absence of RSD, other sleep disorders, psychiatric comorbidities, and medications. RSD was diagnosed per diagnostic criteria.

RESULTS

There were 66 children with ADHD. All of them underwent polysomnography, 17 were females, and 49 were males. Mean age was 11.6 years (± 3.6 standard deviation). The complaint of restless sleep was reported by the parents of 54 (81.1%) of the children; however, only 6 of them (9.1%) were diagnosed with RSD. Seventy-one percent had obstructive sleep apnea and 19.7% had restless legs syndrome. A significant number of patients had psychiatric comorbidities and were on various medications.

CONCLUSIONS

Although restless sleep is a common complaint reported in 81.1% of children with ADHD, only 9.1% had RSD. Most causes of restless sleep are secondary and associated with other sleep disorders, psychiatric comorbidities, or medication use.

Quality Of Sleep And Its Associated Factors Among Diabetics And Non Diabetics

BACKGROUND

Diabetes mellitus is the metabolic state which has shown a persistent global rise in numbers. It is therefore necessary to closely assess all aspects of this state. Sleep quality and diabetic control have a relation where both can affect each other. Therefore, we aim to study the quality of sleep and factors affecting it in our diabetic population. The objective of the study was the identification of quality of sleep and factors affecting it in the diabetic and non diabetic adult population.

METHODS

In this comparative cross sectional study quality of sleep was evaluated in all the patients through the Pittsburgh Sleep Quality Index. Statistical analysis was conducted with the SPSS-23.

RESULTS

The total number of study participants were 250 adults (18 years and above), where 125 were diabetics, while 125 were non diabetics. In Diabetic group, the total number of patients with impaired sleep was 65 (52%). In non-diabetic group, impaired sleep was found in 70 (56%) individuals. The mean age of diabetics was 55.2±11.6 years and non-diabetics was 37.23±12.017 years. Prevalence of restless leg syndrome and depression among diabetics was 33 (26.4%) and 30 (24.0%) respectively and in nondiabetic was 20 (16.0%) and 63 (50.4%). Impaired sleep quality was associated with the use of cell phones before going to bed (p-value: 0.01) and watching television until late at night in both groups. Impaired sleep is seen more commonly in uncontrolled DM (RR:1.462 and CI: 0.531 to 4.025).

CONCLUSIONS

Impaired sleep and uncontrolled DM has a direct relation and the prevalence of Restless leg syndrome (RLS) is higher in Diabetics. Addressing the factors impairing sleep can improve sleep quality and have beneficial effects on the sufferers from this metabolic state.

Bioinformatic analysis of proteomic data for iron, inflammation, and hypoxic pathways in restless legs syndrome

OBJECTIVE/BACKGROUND

We performed bioinformatic analysis of proteomic data to identify the biomarkers of restless legs syndrome (RLS) and provide insights into the putative pathomechanisms, including iron deficiency, inflammation, and hypoxic pathways.

PATIENTS/METHODS

Patients with drug-naïve idiopathic RLS were recruited at a university hospital from June 2017 to February 2018. Serum samples from patients with RLS (n = 7) and healthy sex- and age-matched controls (n = 6) were evaluated by proteomic analysis. For differentially expressed proteins (DEPs) in patients with RLS, compared to those in controls, the expression profiles and protein-protein interaction (PPI) network were characterized between dysregulated proteins and extracted proteins involved in iron deficiency, hypoxia, and inflammation responses using the String database (http://string-DB.org). The PPI network was visualized by Cytoscape ver. 3. 7. 1. Statistical analyses of the validation Western blot assays were performed using a Student's t-test.

RESULTS

Interactome network analysis revealed a relationship among the eight proteins, their associated genes, and 150, 47, and 11 proteins related to iron deficiency, inflammation, and hypoxic pathways, respectively. All DEPs were well associated with inflammation, and complement 3, complement C4A, alpha-2 HS glycoprotein, and alpha-2 macroglobulin precursor were found to be in hub positions of networks involved in PPIs including iron deficiency, hypoxia pathway, and inflammation. C3 and C4A were verified using western blotting.

CONCLUSIONS

We identified key molecules that represent the selected cellular pathways as protein biomarkers by PPI network analysis. Changes in inflammation can mediate or affect the pathomechanism of RLS and can thus act as systemic biomarkers.

Developing a behavioral model of Restless Legs Syndrome utilizing mice with natural variances in ventral midbrain iron

BACKGROUND

The primary symptoms of Restless Legs Syndrome (RLS) are circadian-dependent, leading to increased activity or decreased rest, especially at night. The primary pathology in RLS is brain iron insufficiency despite normal systemic iron stores. Natural variances in brain and peripheral iron concentrations across recombinant inbred (RI) murine strains provide a biological model of RLS. The question is whether these RI mice strains show a behavioral analog to circadian-dependent clinical phenotype of RLS.

METHODS

The home cage activity of eight female RI strains was measured over a 72-h period. The ratio of the average activity in the last 2 h of the active period relative to that in the total 12-h active period (late active period activity ratio, LAPAR) was the primary outcome variable. The relation of average LAPAR scores to measures of ventral midbrain (VMB) iron was evaluated across strains in this study.

RESULTS

RI strain 40 (LAPAR = 1.28) and RI strain 21 (LAPAR = 1.02) were the only strains to show an increased activity in the last part of the active period. ANOVA showed the increased activity was significantly greater during the last 2 h compared to the preceding 10 h of the active phase only for the RI strain 40. Average LAPAR across the eight strains did not significantly correlate with the VMB iron content (r = -0.27, p < 0.10) but did correlate with changes in VMB iron with iron deficiency (r = 0.71, p < 0.05) and diurnal change in VMB iron (r = 0.65, p < 0.05).

CONCLUSION

The female RI strain 40 mice exhibited a distinct end-of-active-period behavior analogous to circadian-dependent clinical phenotype of RLS.

[Sleep Disorders in Old Age]

Sleep Disorders in Old Age Abstract. Sleep disorders increase with age. Older patients rarely complain about sleep disorders, therefore it is important to ask about sleep problems. Insomnias, sleep-disordered breathing and restless legs syndrome tend to increase with older age. It is important to consider that sleep disorders may be the first symptom of a depression, anxiety disorder or neurodegenerative disorders such as dementias. Many factors can influence sleep in old age: it is important to inquire after sleeping habits including naps during the day, medication and comorbidity. Treatment depends on the causes. Insomnias should be treated mainly with non-pharmacological means such as cognitive behaviour therapy.

[Chinese expert consensus on the assessment and management of stroke-related sleep disorders]

Stroke-related sleep disorders (SSD) are common symptoms after stroke, which are common but easily ignored. Studies have shown that sleep disorders in stroke patients would have negative impact on prognosis. However, there is still a lack of consensus and guidance on SSD evaluation and management worldwide. This consensus proposes the concept of SSD based on systemic literature review and discussion with experts. It comprises recommendations of assessment and management for all types of SSD, including insomnia, excessive daytime sleepiness, sleep apnea, rapid eye movement (REM) sleep behavior disorder, restless leg syndrome/periodic limb movements of sleep, circadian rhythm sleep-wake disorders. The purpose of this consensus is to provide a standard reference of SSD management.

Sleep in Parkinson's Disease with Impulse Control Disorder

PURPOSE OF REVIEW

This paper aims to explore the relationship between impulse-control disorders (ICDs) and sleep problems in patients with Parkinson's disease (PD) among scientific literature.

RECENT FINDINGS

Previously published results are controversial and sometimes inconclusive. ICDs and sleep disruption represent important non-motor features of Parkinson's disease, responsible for reducing quality of life and increasing burden of disease. The relationship between sleep problems and ICDs is complex and bidirectional. Indeed, sleep disturbances and fragmentation may play a crucial role in increasing susceptibility to impulsive behavior and may represent a risk factor for developing ICDs in PD patients. Moreover, REM sleep behavior disorder (RBD) and restless legs syndrome (RLS) have been indicated as independent risk factors for ICDs in PD patients. On the other hand, also ICDs may lead to sleep restriction and fragmentation, suggesting a bidirectional relationship. The association between sleep problems and ICDs in PD is far from being completely understood. Further studies are needed to confirm the nature of this relationship and its pathophysiology.

[Drug-Induced Akathisia]

Akathisia consists of subjective inner restlessness, such as awareness of the inability to remain seated, restless legs, fidgetiness, and the desire to move constantly, and of objective increased motor phenomena, such as body rocking, shifting from foot to foot, stamping in place, crossing and uncrossing legs, pacing around. Although the broad definition of akathisia includes the inner and motor restlessness observed in patients with idiopathic Parkinson's disease, post-encephalitic parkinsonism, and restless legs syndrome, here we exclusively focus on the narrow definition of antipsychotic-induced akathisia. The most reliable treatment for acute akathisia is the reduction or the withdrawal of antipsychotic medication. However, this is often not possible because it may worsen the patients' mental condition. Various pharmacological agents have been used for the treatment of this condition. These include anticholinergic agents (e.g., biperiden and trihexyphenidyl), benzodiazepines, beta-adrenoceptor blockers (e.g., propranolol), and serotonin 2A receptor antagonists (e.g., mianserin, cyproheptadine, and mirtazapine).

[Influencing factors of visual hallucinations in patients with Parkinson's disease and its relationship with sleep disorders]

OBJECTIVE

To investigate the prevalence and influencing factors of visual hallucinations in patients with Parkinson's disease(PD), and to analyze the relationship between visual hallucinations and sleep disorders.

METHODS

We recruited 187 patients with PD(H-Y Ⅰ-Ⅲ) from outpatient department in Beijing Hospital. The patients were investigated for general information and the use of medicine. The patients were divided into visual hallucination(VH) group and non-hallucination(non-VH) group. A comparison study was conducted between two groups. We investigated the sleep disorders of PD patients according to Non Motor Symptom Quest(NMSquest) and Parkinson's disease sleep scale(PDSS). Logistic stepwise multiple regression procedures were used to determine the best predictive model of visual hallucinations in patients with PD.

RESULTS

(1) 42 cases(22.5%) of PD patients were accompanied by visual hallucinations; (2) the VH group and non-VH group had no difference in age, sex, duration of illness, the scores of Minimum Mental State Examination(MMSE) and levodopa equivalent doses (LED). The scores of Unified Parkinson's Disease Rating Scale(UPDRS) Ⅰ, the Hamilton Rating Scale for Anxiety(HAMA) and the Hamilton Rating Scale for Depression(HAMD) in VH group were significantly higher than those in non-VH group[3.5(2, 5) vs 2 (1, 3); 10(6.75, 15) vs 8(5, 11); 11(7.75, 17) vs 9(5, 13); P<0.05]; (3) the incidences of vivid dreams and REM sleep behavior disorder(RBD) in VH group were significantly higher than those in non-VH group(61.9% vs 40.7%, 71.4% vs 47.6%, P<0.05). There were no significant differences in incidences of excessive daytime sleepiness and restless legs between two groups(P>0.05). The score of PDSS in VH group was significantly lower than that in non-VH group[111(92.75, 128.25) vs 123(109, 135), P<0.05]; (4) the Logistic stepwise multiple regression revealed that vivid dreams(P=0.045) and the score of PDSS(P=0.006) were the independent influencing factors for VH in PD patients.

CONCLUSIONS

The incidence of VH in PD with H-Y staging Ⅰ-Ⅱ is 22.5%. The presence of vivid dreams and severe sleep disorder are independently associated with VH in PD.