Genetic aspects of restless legs syndrome

Restless legs syndrome in chronic renal failure patients on dialysis

Background

Restless legs syndrome (RLS) occurs in patients with chronic renal failure (CRF).

Objectives

To determine the prevalence and morbidity of RLS in CRF patients on dialysis.

Methods

This cross-sectional questionnaire-based study included 100 dialysis patients (50 on haemodialysis [HD]; 50 on peritoneal dialysis [PD]). A focused lower limb examination was done. Patients were classified with RLS when reporting uncomfortable feelings in their legs that improved with movement and worsened when resting and at night.

Results

Gender distribution was equal. The median age was 43 (19-67) years. Six patients (HD and PD n=3 each) had international criteria-confirmed RLS. Twenty-four patients reported symptoms suggestive of RLS. Fourteen and 16 patients with RLS symptoms were on HD and PD, respectively. Sleep disturbances occurred in 43.3% (n=13) of patients with RLS symptoms, compared to 20.0% (n=20) of the large cohort. Sleep disturbances, peripheral sensory loss, chronic disease-related anaemia, increased urea and decreased albumin levels were more common among patients with RLS symptoms.

Conclusion

RLS symptoms occurred in 30.0% of the entire cohort, although only 6.0% met the international criteria. The type of dialysis had no impact on the incidence of symptoms. Identifying RLS in patients with CRF on dialysis will allow for early intervention.

Attention deficit hyperactivity disorder and restless leg syndrome across the lifespan: A systematic review and meta-analysis

This systematic review aims to assess the association between attention deficit hyperactivity disorder (ADHD) and restless legs syndrome (RLS) in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Databases were searched for original articles that reported prevalence data on ADHD and RLS until January 24th, 2023. Two independent reviewers evaluated the quality of the articles using the National Institutes of Health assessment tool. Among the 208 articles identified between 1996 and 2022, 29 were included. In large general population studies, 2.6-15.3% of participants met the RLS criteria, of which 3.2-17.4% presented with ADHD. In the ADHD group, RLS symptoms ranged from 11 to 42.9% in children and 20-33.0% in adults. This suggests a strong co-occurrence between RLS and ADHD. A common characteristic of these conditions is sleep fragmentation, as discussed in the reviewed papers. Although large-scale studies with comparable diagnostic criteria across the lifespan are required, our findings may advocate a possible common physiological pathway, including sleep fragmentation and dopaminergic system impairment.

Does Dexmedetomidine Improve or Worsen Restless Leg Syndrome under Sedation: A Case Report and Extensive Review

Background

Restless leg syndrome (RLS) is a common neurological condition that manifests as creeping, nonpainful urges to move lower extremities and is relieved with movements of the legs. RLS is associated with comorbidities such as gastric surgery, diabetes mellitus, uremia, and iron deficiency anemia, and it is misdiagnosed in many cases. Drugs like levodopa, ropinirole, pramipexole, cabergoline, and pergolide that target the dopaminergic system have been traditionally used to treat symptoms of RLS. α2-adrenoceptor (α2-AR) agonists, like clonidine and dexmedetomidine, have also been reported to show improvement of RLS symptoms during sedation. Specific Aim. This case report suggests that dexmedetomidine may have worsened RLS during sedation in a 71-year-old male with no prior diagnosis of RLS or reported symptoms. The patient had a procedure for right first metatarsophalangeal joint (MTPJ) fusion, with second digit proximal interphalangeal joint (PIPJ) arthrodesis, and flexor tendon transfer due to pain on walking and failing conservative therapy. He underwent intravenous sedation/monitored anesthesia care (MAC) with propofol, dexmedetomidine, and a peripheral regional block for intraoperative anesthesia and postoperative analgesia. During the surgery, the patient experienced continuous bilateral leg movement, unpredictable, and unrelated to surgical stimulation or level of consciousness within 5 minutes of administration of dexmedetomidine. The patient tolerated the procedure, and the unpredicted leg movement was managed by the surgeons intraoperatively.

Conclusion

Although no previous literature exists and mechanisms are unclear, this case report hypothesizes that dexmedetomidine may contribute to worsening RLS symptoms.

BTBD9 attenuates manganese-induced oxidative stress and neurotoxicity by regulating insulin growth factor signaling pathway

Manganese (Mn) is an essential mineral, but excess exposure can cause dopaminergic neurotoxicity. Restless legs syndrome (RLS) is a common neurological disorder, but the etiology and pathology remain largely unknown. The purpose of this study was to identify the role of Mn in the regulation of an RLS genetic risk factor BTBD9, characterize the function of BTBD9 in Mn-induced oxidative stress and dopaminergic neuronal dysfunction. We found that human subjects with high blood Mn levels were associated with decreased BTBD9 mRNA levels, when compared with subjects with low blood Mn levels. In A549 cells, Mn exposure decreased BTBD9 protein levels. In Caenorhabditis elegans, loss of hpo-9 (BTBD9 homolog) resulted in more susceptibility to Mn-induced oxidative stress and mitochondrial dysfunction, as well as decreased dopamine levels and alternations of dopaminergic neuronal morphology and behavior. Overexpression of hpo-9 in mutant animals restored these defects and the protection was eliminated by mutation of the forkhead box O (FOXO). In addition, expression of hpo-9 upregulated FOXO protein levels and decreased protein kinase B levels. These results suggest that elevated Mn exposure might be an environmental risk factor for RLS. Furthermore, BTBD9 functions to alleviate Mn-induced oxidative stress and neurotoxicity via regulation of insulin/insulin-like growth factor signaling pathway.

Periodic limb movements during sleep: a narrative review

Objective

Using narrative review techniques, this paper evaluates the evidence for separable underlying patho-mechanisms of periodic limb movements (PLMs) to separable PLM motor patterns and phenotypes, in order to elucidate potential new treatment modalities.

Background

Periodic limb movement disorder (PLMD) is estimated to occur in 5–8% of the paediatric population and 4–11% of the general adult population. Due to significant sleep fragmentation, PLMD can lead to functional impairment, including hyperactivity and delayed language development in children, and poor concentration and work performance in adults. Longitudinal data demonstrate that those with PLMD are at greater risk of depression and anxiety, and a 4-fold greater risk of developing dementia. PLMD has been extensively studied over the past two decades, and several key insights into the genetic, pathophysiological, and neural correlates have been proposed. Amongst these proposals is the concept of separable PLM phenotypes, proposed on the basis of nocturnal features such as the ratio of limb movements and distribution throughout the night. PLM phenotype and presentation, however, varies significantly depending on the scoring utilized and the nocturnal features examined, across age, and co-morbid clinical conditions. Furthermore, associations between these phenotypes with major neurologic and psychiatric disorders remain controversial.

Methods

In order to elucidate potential divergent biological pathways that may help clarify important new treatment modalities, this paper utilizes narrative review and evaluates the evidence linking PLM motor patterns and phenotypes with hypothesised underlying patho-mechanisms. Distinctive, underlying patho-mechanisms include: a pure motor mechanism originating in the spinal cord, iron deficiency, dopamine system dysfunction, thalamic glutamatergic hyperactivity, and a more cortical-subcortical interplay. In support of the latter hypothesis, PLM rhythmicity appears tightly linked to the microarchitecture of sleep, not dissimilarly to the apnoeic/hypopneic events seen in obstructive sleep apnea (OSA).

Conclusions

This review closes with a proposal for greater investigation into the identification of potential, divergent biological pathways. To do so would require prospective, multimodal imaging clinical studies which may delineate differential responses to treatment in restless legs syndrome (RLS) without PLMS and PLMS without RLS. This could pave the way toward important new treatment modalities.

New-onset restless leg syndrome in a COVID-19 patient: a case report with literature review

Restless leg syndrome (RLS) is a sleep disorder characterized by the sudden urge to move the lower limbs during periods of rest accompanied by an unpleasant sensation like tingling or burning in the legs. Often, this urge is partially relieved by the movement of legs. However, it causes disturbance of sleep leading to daytime fatigue. Herein, we present an unusual case of new-onset of restless leg syndrome in a COVID-19 infected patient who presented three weeks after an uncomplicated delivery via caesarean section. The patient was managed with sleep hygiene measures, oral iron and vitamin C tablets apart from general COVID-19 management medications, subsequently leading to significant improvements. Here we have discussed possible associated factors, pathophysiological mechanisms and management of RLS in the case of COVID infected individuals.

Mineral absorption is an enriched pathway in a brain region of restless legs syndrome patients with reduced MEIS1 expression

Restless legs syndrome is a common complex disorder with different genetic and environmental risk factors. Here we used human cell lines to conduct an RNA-Seq study and observed how the gene showing the most significant association with RLS, MEIS1, acts as a regulator of the expression of many other genes. Some of the genes affected by its expression level are linked to pathways previously reported to be associated with RLS. We found that in cells where MEIS1 expression was either increased or prevented, mineral absorption is the principal dysregulated pathway. The mineral absorption pathway genes, HMOX1 and VDR are involved in iron metabolism and response to vitamin D, respectively. This shows a strong functional link to the known RLS pathways. We observed the same enrichment of the mineral absorption pathway in postmortem brain tissues of RLS patients showing a reduced expression of MEIS1. The expression of genes encoding metallothioneins (MTs) was observed to be dysregulated across the RNA-Seq datasets generated from both human cells and tissues. MTs are highly relevant to RLS as they bind intracellular metals, protect against oxidative stress and interact with ferritins which manage iron level in the central nervous system. Overall, our study suggests that in a subset of RLS patients, the contribution of MEIS1 appears to be associated to its downstream regulation of genes that are more directly involved in pathways that are relevant to RLS. While MTs have been implicated in the pathogenesis of neurodegenerative diseases such as Parkinson’s diseases, this is a first report to propose that they have a role in RLS.

Use of antidepressants and risks of restless legs syndrome in patients with irritable bowel syndrome: A population-based cohort study

Previous research has suggested an association between antidepressants use and clinical restless legs syndrome (RLS) in patients, but there has never been a single study investigating the risk of RLS in irritable bowel syndrome (IBS) patients treated with antidepressants. Hence, we aimed to explore the association between IBS and RLS and to examine the risk of RLS in IBS patients treated with antidepressants. With the use of the National Health Insurance Research Database of Taiwan, 27,437 adults aged ≥ 20 years with newly diagnosed IBS (ICD-9-CM Code 564.1) and gender- and age-matched 54,874 controls without IBS were enrolled between 2000 and 2012. All patients were followed-up until RLS diagnosis, withdrawal from the National Health Insurance program, or end of 2013. We used the Cox proportional hazards model to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of RLS. RLS was more prevalent in IBS patients than in the non-IBS group (7.57 versus 3.36 per 10,000 person-years), with an increased risk of RLS (adjusted HR [aHR], 1.91; 95% CI, 1.52-2.40). Multivariate Cox proportional hazards analysis identified older age (age, 51-65 years; aHR, 1.67; 95% CI, 1.09-2.56; and age > 65; aHR, 1.59; 95% CI, 1.02-2.48), hypothyroidism (aHR, 4.24; 95% CI, 1.92-9.37), CAD (aHR, 1.70; 95% CI, 1.17-2.48), and depression (aHR, 3.15; 95% CI, 2.14-4.64) as independent RLS risk factors in IBS patients. In addition, the male SSRIs users were associated with significantly higher risk of RLS (aHR, 3.05 95% CI, 1.34-6.92). Our study showed that the IBS group has higher risk of RLS. Moreover, SSRIs use may increase the risk of RLS in male IBS patients.

Restless legs syndrome

Restless legs syndrome (RLS), also known as Willis-Ekbom disease (WED), is a common movement disorder characterised by an uncontrollable urge to move because of uncomfortable, sometimes painful sensations in the legs with a diurnal variation and a release with movement. The pathophysiology is only partially known and a genetic component together with dopaminergic and brain iron dysregulation plays an important role. Secondary causes for RLS need to be excluded. Treatment depends on the severity and frequency of RLS symptoms, comprises non-pharmacological (eg lifestyle changes) and pharmacological interventions (eg dopaminergic medication, alpha-2-delta calcium channel ligands, opioids) and relieves symptoms only. Augmentation is the main complication of long-term dopaminergic treatment of RLS. This article will provide a clinically useful overview of RLS with provision of diagnostic criteria, differential diagnoses, possible investigations and different treatment strategies with their associated complications.

Sleep in Autism Spectrum Disorders

Autism spectrum disorders (ASD) are common neurodevelopmental conditions, affecting 1 in 68 children. Sleep disturbance, particularly insomnia, is very common in children diagnosed with ASD, with evidence supporting overlapping neurobiological and genetic underpinnings. Disturbed sleep exacerbates core and related ASD symptoms and has a substantial negative impact on the entire family. Treatment of sleep disturbance holds promise for ameliorating many of the challenging behavioral symptoms that children with ASD and their families face. Behavioral and pharmacological studies indicate promising approaches to treating sleep disturbances in this population. Awareness of treatment options is particularly important as parents and clinicians may believe that sleep disturbance is part of autism and refractory to therapy. In addition, autism symptoms refractory to treatment with conventional psychiatric medications may improve when sleep is addressed. Additional evidence-based studies are needed, including those that address the underlying biology of this condition.