MEIS1 variant as a determinant of autonomic imbalance in Restless Legs Syndrome

Self-administered non-invasive vagus nerve stimulation therapy for severe pharmacoresistant restless legs syndrome: outcomes at 6 months

Severe pharmacoresistant restless legs syndrome (RLS) is difficult to manage and a source of suffering to patients. We studied the effectiveness at 6 months of an innovative treatment: transauricular vagus nerve stimulation (taVNS) in the left cymba concha in a case series of 15 patients, 53% male, mean (SD) age 62.7 (12.3) years with severe pharmacoresistant RLS (mean [SD] International Restless Legs Rating Scale [IRLS] score of 31.9 [2.9]) at baseline. Following an 8-week non-randomised hospital-based study with eight 1-h sessions of taVNS, patients were trained to administer taVNS at home and were followed up for 6 months. The primary outcome measure was the IRLS score, secondary outcome measures were quality of life, mood disorders using the Hospital Anxiety and Depression scale (HAD) subscales for depression (HADD) and anxiety (HADA). At the 6-month follow-up 13/15 patients continued to use weekly taVNS. Symptom severity decreased (mean [SD] IRLS score 22.2 [9.32] at 6 months, p = 0.0005). Four of the 15 patients had an IRLS score of <20 at 6 months and two an IRLS score of 5. Quality of life significantly improved compared to baseline (mean [SD] score at baseline 49.3 [18.1] versus 65.66 [22.58] at 6 months, p = 0.0005) as did anxiety and depression symptoms (mean [SD] HADA score at baseline 8.9 [5.4] versus 7.53 [4.42] at 6 months, p = 0.029; and HADD score at baseline 5.2 [4.5] versus 4.73 [4.44] at 6 months, p = 0.03). Treatment was well tolerated, and no adverse events were reported. Our case series shows a potential role for self-administered taVNS in patients with severe pharmacoresistant RLS. Randomised controlled trials are needed to confirm the utility of taVNS.

Restless legs syndrome: From clinic to personalized medicine

Restless legs syndrome (RLS) is a common neurological sensorimotor disorder that impairs sleep, mood and quality of life. RLS is defined by an urge to move the legs at rest that increases in the evening and at night, and is frequently associated with metabolic and cardiovascular diseases. Symptoms frequency, age at RLS onset, severity, familial history and consequences of RLS vary widely between patients. A genetic susceptibility, iron deficiency, dopamine deregulation, and possible hypo-adenosinergic state may play a role in the pathophysiology of RLS. Polysomnographic recordings found often periodic leg movements during sleep and wakefulness in patients with RLS. RLS can be classified as primary or comorbid with major diseases: iron deficiency, renal, neurological, rheumatological and lung diseases. First-line treatments are low-dose dopamine agonists, and alpha-2-delta ligands depending on the clinical context, and second/third line opiates for pharmacoresistant forms of RLS. Augmentation syndrome is a serious complication of dopamine agonists and should be prevented by using the recommended low dose. Despite an increase in knowledge, RLS is still underdiagnosed, poorly recognized, resulting in substantial individual health burden and socioeconomic coast, and education is urgently needed to increase awareness of this disabling disorder.

Noninvasive Vagus Nerve Stimulation: A New Therapeutic Approach for Pharmacoresistant Restless Legs Syndrome

AIMS

This work aimed to study the effect of noninvasive vagus nerve stimulation on severe restless legs syndrome (RLS) resistant to pharmacotherapy.

MATERIALS AND METHODS

Patients with severe pharmacoresistant RLS were recruited from a tertiary care sleep center. Intervention was one-hour weekly sessions of transauricular vagus nerve stimulation (tVNS) in the left cymba concha, for eight weeks. The primary outcome measure was the score on the International Restless Legs Rating Scale (IRLS); secondary outcome measures were quality of life (Restless Legs Syndrome Quality of Life scale [RLSQOL]), mood disorders using the Hospital Anxiety and Depression scale subscale for depression (HADD) and Hospital Anxiety and Depression scale subscale for anxiety (HADA), and objective sleep latency, sleep duration, efficiency, and leg movement time measured by actigraphy.

RESULTS

Fifteen patients, 53% male, aged mean 62.7 ± 12.3 years with severe RLS, reduced quality of life, and symptoms of anxiety and depression, were included. The IRLS improved from baseline to session eight: IRLS 31.9 ± 2.9 vs 24.6 ± 5.9 p = 0.0003. Of these participants, 27% (4/15) had a total response with a decrease below an IRLS score of 20; 40% (6/15) a partial response with an improvement in the IRLS > 5 but an IRLS above 20; and 33% (5/15) were nonresponders. After tVNS, quality of life improved (RLSQOL 49.3 ± 18.1 vs 80.0 ± 19.6 p = 0.0005), as did anxiety (HADA 8.9 ± 5.4 vs 6.2 ± 5.0 p = 0.001) and depression (HADD 5.2 ± 4.5 vs 4.0 ± 4.0 p = 0.01). No significant change was found in actigraphic outcome measures.

CONCLUSIONS

In this pilot study, tVNS improved the symptoms of RLS in 66% of participants (10/15) with severe pharmacoresistant RLS, with concomitant improvements in quality of life and mood. Randomized controlled trials evaluating therapeutic efficacy of tVNS in RLS are needed to confirm these promising findings.

The autism-associated Meis2 gene is necessary for cardiac baroreflex regulation in mice

Recent understanding of Autism Spectrum Disorder (ASD) showed that peripheral primary mechanosensitive neurons involved in touch sensation and central neurons affected in ASD share transcriptional regulators. Mutant mice for ASD-associated transcription factors exhibit impaired primary tactile perception and restoring those genes specifically in primary sensory neurons rescues some of the anxiety-like behavior and social interaction defects. Interestingly, peripheral mechanosensitive sensory neurons also project to internal organs including the cardiovascular system, and an imbalance of the cardio-vascular sympathovagal regulation is evidenced in ASD and intellectual disability. ASD patients have decreased vagal tone, suggesting dysfunction of sensory neurons involved in cardio-vascular sensing. In light of our previous finding that the ASD-associated Meis2 gene is necessary for normal touch neuron development and function, we investigated here if its inactivation in mouse peripheral sensory neurons also affects cardio-vascular sympathovagal regulation and baroreflex. Combining echocardiography, pharmacological challenge, blood pressure monitoring, and heart rate variability analysis, we found that Meis2 mutant mice exhibited a blunted vagal response independently of any apparent cardiac malformation. These results suggest that defects in primary sensory neurons with mechanosensitive identity could participate in the imbalanced cardio-vascular sympathovagal tone found in ASD patients, reinforcing current hypotheses on the role of primary sensory neurons in the etiology of ASD.

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.

Polysomnographic nighttime features of Restless Legs Syndrome: A systematic review and meta-analysis

Background

Restless Legs Syndrome (RLS) is a common sleep disorder. Polysomnographic (PSG) studies have been used to explore the night sleep characteristics of RLS, but their relationship with RLS has not been fully analyzed and researched.

Methods

We searched the Cochrane Library electronic literature, PubMed, and EMBASE databases to identify research literature comparing the differences in polysomnography between patients with RLS and healthy controls (HCs).

Results

This review identified 26 studies for meta-analysis. Our research found that the rapid eye movement sleep (REM)%, sleep efficiency (SE)%, total sleep time (TST) min, and N2 were significantly decreased in patients with RLS compared with HCs, while sleep latency (SL) min, stage shifts (SS), awakenings number (AWN), wake time after sleep onset (WASO) min, N1%, rapid eye movement sleep latency (REML), and arousal index (AI) were significantly increased. Additionally, there was no significant difference among N3%, slow wave sleep (SWS)%, and apnea-hypopnea index (AHI).

Conclusion

Our findings demonstrated that architecture and sleep continuity had been disturbed in patients with RLS, which further illustrates the changes in sleep structure in patients with RLS. In addition, further attention to the underlying pathophysiological mechanisms of RLS and its association with neurodegenerative diseases is needed in future studies.

Restless legs syndrome: Over 50 years of European contribution

Restless legs syndrome (RLS) is a sensorimotor neurological disorder characterised by an urge to move the limbs with a circadian pattern (occurring in the evening/at night), more prominent at rest, and relieved with movements. RLS is one of the most prevalent sleep disorders, occurring in 5%-10% of the European population. Thomas Willis first described RLS clinical cases already in the 17th century, and Karl-Axel Ekbom described the disease as a modern clinical entity in the 20th century. Despite variable severity, RLS can markedly affect sleep (partly through the presence of periodic leg movements) and quality of life, with a relevant socio-economic impact. Thus, its recognition and treatment are essential. However, screening methods present limitations and should be improved. Moreover, available RLS treatment options albeit providing sustained relief to many patients are limited in number. Additionally, the development of augmentation with dopamine agonists represents a major treatment problem. A better understanding of RLS pathomechanisms can bring to light novel treatment possibilities. With emerging new avenues of research in pharmacology, imaging, genetics, and animal models of RLS, this is an interesting and constantly growing field of research. This review will update the reader on the current state of RLS clinical practice and research, with a special focus on the contribution of European researchers.

Heart rate variability during sleep in children and adolescents with restless sleep disorder: a comparison with restless legs syndrome and normal controls

STUDY OBJECTIVES

Restless sleep disorder (RSD) has recently been characterized clinically and polysomnographically in children and differentiated from restless legs syndrome (RLS). Heart rate variability is a reliable method to quantify autonomic changes during sleep. The aim of this study was to characterize heart rate variability in children with RSD, RLS, and individuals without these disorders, with the hypothesis that children with RSD have a shift toward sympathetic predominance during sleep.

METHODS

We analyzed polysomnographic recordings from 32 children who fulfilled RSD diagnostic criteria (19 boys and 13 girls), 32 children with RLS (20 boys and 12 girls), and 33 individuals without disorders (17 boys and 16 girls). Four electrocardiographic epochs were chosen, 1 for each stage, and were analyzed for automatic detection of R waves. Time domain and frequency domain heart rate variability parameters were obtained and analyzed.

RESULTS

In terms of time domain, only the standard deviation of the average interval between successive R waves during stage N3 was slightly but significantly higher in patients with RSD than in patients with RLS. In terms of frequency domain, in patients with RSD, the very-low-frequency and low-frequency bands were increased (vs patients with RLS and individuals without disorders, respectively), whereas low-frequency/high-frequency ratio tended to be increased in both patients with RSD and with RLS. In rapid eye movement sleep, low-frequency/high-frequency ratio was increased in both patients with RSD and with RLS. The low-frequency/high-frequency ratio increased in patients with RLS during quiet wakefulness preceding sleep.

CONCLUSIONS

Children with RSD have increased sympathetic activation during sleep, particularly N3 and rapid eye movement sleep, compared with individuals without disorders but, as expected, not during wakefulness. Differently, children with RLS have sympathetic activation during relaxed wakefulness preceding sleep and during sleep.

Systematic assessment of autonomic symptoms in restless legs syndrome

OBJECTIVES

To compare the clinical features of autonomic dysfunction using the SCOPA-AUT questionnaire in untreated patients with restless legs syndrome (RLS) with controls, to identify factors associated with more severe autonomic symptoms, and to assess the effect of medication in patients.

METHODS

The SCOPA-AUT questionnaire that evaluates cardiovascular, gastrointestinal, urinary, thermoregulatory, pupillomotor, and sexual dysfunctions was completed by 409 consecutive untreated patients with RLS (54.1 ± 14.5 y.o; 265 women) and 331 controls (59.0 ± 17.0; 161 women). Clinical and polysomnographic data were assessed in all patients. A subgroup of 57 patients were evaluated a second time after treatment (mostly dopaminergic agonist) after an interval of 0.88 ± 1.42 year.

RESULTS

Compared to controls, untreated patients with RLS were younger, more often women, obese, with increased cardiovascular diseases (CVD). The SCOPA-AUT total score was higher in patients than controls in unadjusted and adjusted models. Patients had more autonomic symptoms in all subdomains of the scale (except for sexual dysfunction in men). These results were confirmed in a subgroup of 259 cases and age-sex-matched controls. Female gender, obesity, RLS severity, diabetes mellitus, CVD, sleepiness, insomnia and depressive symptoms but neither periodic legs movements during sleep (PLMS) nor objective sleep parameters were associated with high scores. Despite RLS and PLMS improvement, medication did not change total and subdomain scores.

CONCLUSIONS

Patients with RLS have frequent and large spectrum of autonomic symptoms, without effect of PLMS, sleep fragmentation and medication. These results suggest a global autonomic dysfunction in RLS that should be assessed more systematically in severe patients.

Blood pressure profile and endothelial function in restless legs syndrome

Restless legs syndrome (RLS) is frequently comorbid with hypertension and cardiovascular diseases; however this relationship and underlying mechanisms remain controversial. After clinical evaluation, 84 drug-free patients with primary RLS (53 women; mean age 55.1 ± 12.3 years) and 76 controls (47 women; mean age 52.2 ± 15.3 years) underwent 24-hour ambulatory blood pressure (BP) and polysomnographic monitoring, and peripheral arterial tonometry to assess endothelial function for 61 patients and 69 controls. Hypertension was diagnosed in 11.9% of patients with RLS based on office measurement, and in 46.4% on the 24 h recording, with nighttime hypertension, two times more frequent than daytime hypertension. Periodic limb movement during sleep (PLMS), markers of sleep fragmentation, and systolic and mean BP non-dipping profile were more frequent among patients. BP non-dipping status was associated with older age, later RLS onset and diagnosis, RLS severity and higher sleep fragmentation. The mean 24-hour, daytime and nighttime BP values, the frequency of hypertension and the endothelial function were comparable between groups. However, both systolic and diastolic BP trajectories over a 24-hour period differed between groups. In conclusion, patients with RLS exhibit a 24-hour BP deregulation with increased frequency of systolic non-dipping profiles that could worsen the risk for CVD morbidity and mortality.

Increased blood pressure during the suggested immobilization test in Restless Legs Syndrome

Objective

To investigate the relationship between sensory discomfort/motor component and cardiovascular autonomic response by continuous beat-to-beat blood pressure monitoring (CBPM) during the suggested immobilization test (SIT) in patients with restless legs syndrome (RLS).

Methods

Thirty-two drug-free patients with primary RLS (10 men; mean age 60.29 ± 10.81 years) and 17 healthy controls (2 men; mean age 58.82 ± 11.86 years) underwent a 1-hour SIT starting at 8 pm with concomitant CBPM to measure the heart rate (HR) and systolic/diastolic blood pressure (SBP, DBP). In all subjects, the presence of sensory discomfort and motor component during the SIT (S-SIT+ and M-SIT+, respectively) was quantified. Mixed regression models were used to compare the SBP, DBP, and HR profiles during the SIT by taking into account the repeated measures (6 time periods of 10 minutes).

Results

In patients with S-SIT+ (n = 17), SBP (p &lt; 0.0001), DBP (p = 0.0007), and HR (p = 0.03) increased during the SIT compared with other patients and controls. Seventeen patients had M-SIT+ (none among healthy controls). Classifying patients in 4 groups in function of the presence/absence of the SIT sensory and motor components revealed that SDB and DBP increased throughout the SIT in patients with S-SIT+, independently of the motor component (p &lt; 0.0001 and p = 0.0008 for SBD; p &lt; 0.0001 and p = 0.01 for DBP in the S-SIT+/M-SIT− and S-SIT+/M-SIT+ groups, respectively).

Conclusion

During the SIT, BP concomitantly increased only in patients with RLS and sensory discomfort, with or without motor component. This highlights the link between evening sensory RLS symptoms, autonomic activation, and potential long-term cardiovascular consequences.

Determinants of Nocturnal Cardiovascular Variability and Heart Rate Arousal Response in Restless Legs Syndrome (RLS)/Periodic Limb Movements (PLMS)

Recent studies have suggested that restless legs syndrome is associated with an increased prevalence of cardiovascular diseases mediated by sympathetic activation occurring during periodic limb movements. The aim of this study was to establish which factors affect the degree of sympathetic activation during the basal condition and during periodic limb movements that may contribute to increased vascular risk. Fifty untreated restless legs syndrome patients aged 62.6 ± 11.1 y, free of cardiovascular diseases, were examined. Heart rate variability was calculated during wakefulness and all sleep stages, during periods with and without periodic limb movements. Heart rate changes before and after periodic limb movement onset were analyzed to assess the arousal response to periodic limb movements. Both analyses took into account the effects of age, gender, periodic limb movement duration, periodic limb movement index, periodic limb movement interval and periodicity, and magnitude of muscular activity (electromyogram power). Compared to periods without periodic limb movements, a significant increase in sympathetic activity occurred in periods with periodic limb movements, independent of age, sex and periodic limb movement characteristics. Data obtained from the cardiac arousal response to periodic limb movements showed that electromyogram power is the factor affecting sympathetic tonus. These results suggest that other factors, such as electromyogram power and individual susceptibility, should be considered in the assessment of the vascular risk related to restless legs syndrome.

Gene Regulatory Networks in Peripheral Mononuclear Cells Reveals Critical Regulatory Modules and Regulators of Multiple Sclerosis

Multiple sclerosis (MS) is a complex, demyelinating disease with the involvement of autoimmunity and neurodegeneration. Increasing efforts have been made towards identifying the diagnostic markers to differentiate the classes of MS from other similar neurological conditions. Using a systems biology approach, we constructed four types of gene regulatory networks (GRNs) involved in peripheral blood mononuclear cells (PBMCs). The regulatory strength of each GRN across primary progressive MS (PPMS), relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), and control were evaluated by an integrity algorithm. Among the constructed GRNs (referred as TF_gene_miRNA), POU3F2_CDK6_hsa-miR-590-3p, MEIS1_CASC3_hsa-miR-1261, STAT3_OGG1_hsa-miR-298, and TCF4_FMR1_hsa-miR-301b were top-ranked and differentially regulated in all classes of MS compared to control. These GRNs showed potential involvement in regulating various molecular pathways such as interleukin, integrin, glypican, sphingosine phosphate, androgen, and Wnt signaling pathways. For validation, the qPCR analysis of the GRN components (TFs, gene, and miRNAs) in PBMCs of healthy controls (n = 30), RRMS (n = 14), PPMS (n = 13) and SPMS (n = 12) were carried out. Real-time expression analysis of GRNs showed a similar regulatory pattern as derived from our systems biology approach. Also, our study provided several novel GRNs that regulate unique and common molecular mechanisms between MS conditions. Hence, these regulatory components of GRNs will help to understand the disease mechanism across MS classes and further insight may though light towards diagnosis.

Discovery of restless legs syndrome plasmatic biomarkers by proteomic analysis

OBJECTIVES

Restless legs syndrome (RLS) can lead to severe clinical consequences, thus negatively impacts on patients' overall health and quality of life. Nevertheless, the pathophysiology of RLS is still unclear, resulting in underestimate, incorrect, or ignored diagnosis and in limited management and treatment. The aim of this study was to compare the plasma proteome of RLS patients and healthy controls, in the search of diagnostic biomarkers related to the disease severity.

MATERIALS AND METHODS

Two-dimensional gel electrophoresis coupled with liquid chromatography-mass spectrometry was employed to analyze plasma samples of 34 patients with primary RLS, divided into two subgroups according to the disease severity: MMS group (mild-moderate symptoms) and HS group (severe and very severe symptoms), and 17 age- and sex-matched control subjects. Sleep quality, daytime sleepiness, and the level of depression were also evaluated.

RESULTS

We identified eight upregulated spots, corresponding to five unique proteins, in both RLS group vs. controls (alpha-1B-glycoprotein, alpha-1-acid glycoprotein 1, haptoglobin, complement C4-A, and immunoglobulin kappa constant); five increased spots, consistent with three unique proteins, only in HS-RLS (kininogen-1, immunoglobulin heavy constant alpha 1, and immunoglobulin lambda constant 2); one downregulated spot in both patient's groups (complement C3) and another one only in HS-RLS (alpha-1-antitrypsin).

CONCLUSIONS

The significantly different plasma proteins detected in RLS were mainly associated with inflammation, immune response, and cardiovascular disorders. Particularly, the gradual increasing in immunoglobulins could be indicative of the disease severity and evolution. Accordingly, these proteins may represent a valid set of useful biomarkers for RLS diagnosis, progression and treatment.