Restless legs syndrome

Prevalence of restless legs syndrome in people with diabetes mellitus: A pooling analysis of observational studies

BACKGROUND

Diabetes mellitus (DM) is associated with different clinical complications. The aim of this study was to explore the prevalence of RLS in people with diabetes mellitus and compare the risk of restless leg syndrome (RLS) between diabetic and non-diabetic population.

METHODS

We searched for studies of RLS prevalence in DM through PubMed, Embase, and Web of Science. Two authors independently completed the literature screening, data extraction, and bias risk assessment of eligible studies. All observational studies that assessed the prevalence or risk of RLS in DM were included, where the diagnosis of RLS was based on the International Restless Legs Syndrome Study Group (IRLSSG). Percentages, odds ratio (OR) with 95% confidence intervals (CI) were used to assess pooled estimates of RLS prevalence and risk based on random-effects models. Newcastle-Ottawa-scale (NOS) or a modified NOS were used to evaluate the quality of studies.

FINDINGS

A total of 42 studies, including 835,986 participants, met the eligibility criteria for the meta-analysis. Among them, 30 studies were included in meta-analysis to analyze the prevalence of RLS. A second meta-analysis was conducted using 31 studies to determine RLS risk between diabetes and non-diabetes. The results indicate that between 25% (95% confidence interval 21%-29%) of people with diabetes showed signs of RLS, and people with diabetes had an increased risk of developing RLS compare to people without diabetes (OR 1.98, 95%CI 1.66- 2.34, p < 0.001). However, the available evidence was limited due to potential risk of bias and variability between studies (I² >75%), all of observational design.

INTERPRETATION

Our study suggests that the prevalence and risk of RLS might be higher in DM patients than in non-diabetes population. However, given limitations in the analysis and study design, the findings need to be corroborated in future studies.

FUNDING

This work was supported by the Basic Conditions Platform Construction Project of Sichuan Science and Technology Department (2019JDPT0015), and the "1・3・5 project for disciplines of excellence, West China Hospital, Sichuan University" (ZYJC18003).

D3 Receptors and Restless Legs Syndrome

Restless Legs Syndrome (RLS) is a sensorimotor disorder that severely affects sleep. It is characterized by an urge to move the legs that is often accompanied by periodic limb movements during sleep (PLMS). RLS has a high prevalence in the population and is usually a life-long condition. While its origins remain unclear, RLS is initially highly responsive to treatment with dopaminergics that target the D3 receptor. However, over time patients often develop a gradual tolerance that can lead to the emergence of adverse effects and the augmentation of the symptoms. While the basal ganglia and the striatum control leg movements, the lumbar spinal cord is the gateway for the sensory processing of the symptoms and critical for the associated leg movements. D3 receptors are highly expressed in nucleus accumbens (NAc) of the striatum and the sensory-processing areas of the spinal dorsal horn. In contrast, D1 receptors are strongly expressed throughout the entire striatum and in the ventral horn of the spinal cord. Long-term treatment with D3 receptor full agonists is associated with an upregulation of the D1 receptor subtype, and D3 and D1 receptors can form functional heteromers, in which the D3R controls the D1R function. It is conceivable that the switch from beneficial treatment to augmentation observed in RLS patients after prolonged D3R agonist exposure may be the result of unmasked D1-like receptor actions.

Restless legs syndrome in people with multiple sclerosis: An updated systematic review and meta-analyses

BACKGROUND

Restless legs syndrome (RLS) is a sensory-motor disorder characterized by an uncomfortable sensation felt in the lower extremity. The aim of this systematic review and meta-analyses was (i) to provide updated information on the prevalence and clinical characteristics of RLS amongst people with multiple sclerosis (PwMS) and (ii) clarify RLS-related factors in PwMS.

METHODS

MEDLINE (PubMed), Scopus, and EMBASE were searched from their inception through April 2021 for the following keywords: 'restless legs syndrome' or 'RLS' and 'multiple sclerosis' or 'MS'. For the analysis of RLS prevalence, we calculated the percentage of RLS sufferers amongst the PwMS and people without MS. The prevalence of RLS was pooled separately for PwMS and healthy controls, regardless of the heterogeneity between studies. The odds ratios (ORs) and 95% CIs were extracted from the data in order to analyze the association between MS and RLS.

RESULTS

Nineteen studies were included in the review (9 case-controlled and 10 cross-sectional).The mean prevalence of RLS in the MS population was 27.5%, ranging from 13.2% to 65.1%, higher than the healthy controls. Based on the case control studies, the pooled RLS prevalence was much higher in PwMS than in healthy controls (OR 4.535, 95% CI 3.043-6.759, p<0.001). The majority of studies found no significant relationship between the presence of RLS in PwMS with disability, disease duration, type of MS, age, or gender.

CONCLUSIONS

Our updated systematic review strengthens the evidence of the increased risk of RLS amongst PwMS. Nevertheless, significant data reporting on characteristics of the MS disease, which increases the risk of suffering from RLS, is still lacking.

Restless legs syndrome and multiple sclerosis: a Brazilian multicenter study and meta-analysis of the literature

OBJECTIVE: The increased prevalence of restless legs syndrome (RLS) in multiple sclerosis (MS) has recently been the subject of a few papers. The present study investigated the prevalence of RLS symptoms in MS patients and in controls in four Brazilian cities. Additionally, a systematic review and meta-analysis of the literature was carried out on the subject of RLS-MS. METHOD: MS patients and controls were investigated regarding the presence of the four typical symptoms of RLS. A questionnaire assessing RLS severity was also used for patients and controls presenting the four RLS symptoms criteria. The systematic review and meta-analysis on the subject were carried out according to the strict international criteria. RESULTS: In the present report, the RLS-MS association was confirmed as being more than fortuitous in Brazilian MS patients, in a multicenter case-control study. MS patients also presented RLS symptoms of greater severity than did the control population. A systematic review and meta-analysis of the literature showed that MS patients had a fourfold higher chance of presenting RLS than did the controls. CONCLUSION: Although underlying mechanisms to explain the association RLS-MS are still a matter of discussion, there is a clear association of these two neurological conditions.

Epidemiology of restless legs syndrome in Turkish adults on the western Black Sea coast of Turkey: A door-to-door study in a rural area

OBJECTIVE

To determine the prevalence and clinical presentation of restless legs syndrome (RLS) in Turkish population living in Kandira, a town located on the Black Sea coast of Istanbul.

METHODS

This study was designed as a descriptive, cross-sectional, door-to-door field study. A total of 2111 people aged 18 years and over were selected for the study. The criteria suggested by the IRLSSG (International Restless Legs Syndrome Study Group) were used in the assessment of RLS. All the suspected subjects underwent neurological examination.

RESULTS

The prevalence of RLS was found to be 3.4% of Turkish population aged over 18. Female:male ratio was 3.5:1. The prevalence reached peak point (8.3%) in the 58- to 67-year-old group. Prevalence of DM, anemia and polyneuropathy in RLS patients was 13.9%, 8.3% and 4.2%, respectively.

CONCLUSION

RLS prevalence is relatively low, but increases with age in both genders in this Turkish population. Although it has negative effects on daily life, it is not well recognized by the population.

Unaltered D1, D2, D4, and D5 dopamine receptor mRNA expression and distribution in the spinal cord of the D3 receptor knockout mouse

Dopamine (DA) acts through five receptor subtypes (D1-D5). We compared expression levels and distribution patterns of all DA mRNA receptors in the spinal cord of wild-type (WT) and loss of function D3 receptor knockout (D3KO) animals. D3 mRNA expression was increased in D3KO, but no D3 receptor protein was associated with cell membranes, supporting the previously reported lack of function. In contrast, mRNA expression levels and distribution patterns of D1, D2, D4, and D5 receptors were similar between WT and D3KO animals. We conclude that D3KO spinal neurons do not compensate for the loss of function of the D3 receptor with changes in the other DA receptor subtypes. This supports use of D3KO animals as a model to provide insight into D3 receptor dysfunction in the spinal cord.

Reversal of the circadian expression of tyrosine-hydroxylase but not nitric oxide synthase levels in the spinal cord of dopamine D3 receptor knockout mice

Circadian rhythms have been described for numerous transmitter synthesizing enzymes in the brain but rarely in spinal cord. We measured spinal tyrosine-hydroxylase (TH) and nitric oxide synthase (NOS) levels in the thoracic intermediolateral nucleus, the location of sympathetic preganglionic neurons, in male wild type (WT) and dopamine D(3) receptor knockout mice (D(3)KO). TH and NOS levels both displayed circadian patterns in WT and D(3)KO animals with overall reduced TH and increased NOS expression in the D(3)KO mice. The circadian pattern of NOS expression was similar in WT and D(3)KO mice. In contrast, TH expression was inverted in D(3)KO mice, with TH levels consistently lower than in WT throughout the day, but strongly increased temporarily 1 h prior to daylight. TH is the rate-limiting enzyme for the production of dopamine. Spinal dopamine dysfunction is implicated in a sleep disorder called restless legs syndrome (RLS). RLS follows a circadian rhythm and is relieved clinically by dopamine D(3) receptor agonists. Our observations of an altered circadian pattern in spinal dopamine synthesis in D(3)KO animals may provide insight into putative dopaminergic mechanisms contributing to RLS.

Analysis of familial and sporadic restless legs syndrome in age of onset, gender, and severity features

Restless Legs Syndrome is characterized by the irresistible, often indescribable unpleasant urge to move the limbs while resting. It has an estimated prevalence of approximately 29.3 % in US private practice. Restless Legs Syndrome often has a familial component; whether the familial and non-familial forms differ in terms of clinical features has previously been investigated, with the only significant factor emerging as younger age at onset in familial cases. Our study further explores a possible underlying difference between familial and sporadic forms of RLS by comparing familial RLS with sporadic RLS in terms of demographic and clinical features including subject gender, age of onset, and severity measures based an the IRLSSG severity scale. Both gender and family history are significant predictors of onset age in an overall model and also significant when analyzed independently. Participants who reported more severe RLS symptoms were significantly younger in age and progressed more rapidly. Two variables from the IRLSSG severity scale were significantly associated with age of onset when tested independently: discomfort and the urge to move the limb for relief. Our analysis supports the prevailing hypothesis that RLS is divided into earlier onset disease with a clear genetic component and later onset disease with unclear etiology, and that one or more endophenotypes might exist within the disorder which could further characterize these subjects for future genetic studies.

Diagnosing restless legs syndrome (RLS) in primary care

This paper represents a review of current opinion and information on the effective diagnosis of restless legs syndrome (RLS) in a primary care setting. RLS can be a distressing condition--it can cause serious sleep disturbance and has a significant impact on quality of life comparable to that of depression or type 2 diabetes. The prevalence of adults whose RLS is severe enough to warrant medical advice has been estimated to be approximately 3%, but only a small proportion of these patients currently report having been diagnosed in primary care, despite stating that they have presented to their GP. The benefits of increased understanding of the symptoms of RLS and how patients present in primary care are discussed, with emphasis on how this will help GPs more effectively diagnose and manage the patients affected. Guidelines on how to diagnose RLS in a primary care setting are given--when a patient presents with sleep disturbance, RLS should be routinely considered and, where existing, be readily diagnosed in a primary care setting on the basis of the patient's clinical history, a physical examination and with the aid of four questions based on the International RLS Study Group (IRLSSG) four essential diagnostic criteria.

A double-blind, placebo-controlled trial of intravenous iron dextran therapy in patients with ESRD and restless legs syndrome

BACKGROUND

Restless legs syndrome (RLS) is a common disorder in patients with end-stage renal disease (ESRD) that causes motor agitation and insomnia. Because RLS has been associated with iron deficiency, we sought to investigate the effects of intravenous (IV) iron dextran on symptoms of RLS in a double-blind placebo-controlled trial.

METHODS

Patients determined to have RLS by International RLS Study Group criteria were administered either iron dextran, 1,000 mg, or normal saline IV in a blinded fashion. Patient demographic data were collected, and blood chemistry tests, liver function studies, serum iron levels, ferritin levels, and total iron-binding capacity were obtained at baseline and 1, 2, and 4 weeks postinfusion. Side effects or adverse events to interventions were monitored, and RLS symptoms were assessed by a rating scale at the same intervals.

RESULTS

Eleven patients were randomly assigned to the administration of iron dextran, and 14 patients to the administration of saline. RLS severity scores were slightly higher in the placebo group at baseline, but hemoglobin levels, iron stores, and other biochemical parameters did not differ. Although no change in symptoms were seen in the placebo-treated group, significant improvement in RLS symptom scores in response to iron dextran was seen 1 week after infusion (-2; interquartile range [IQR], -6 to -1; P = 0.03, Wilcoxon's rank sums), but was greatest at 2 weeks (-3; IQR, -5 to -2 compared with -1 to 0; P = 0.01). Salutary effects of iron persisted at 4 weeks, but were no longer statistically significant. The significant increase in serum ferritin levels and iron saturation observed in the iron dextran-treated group was not seen in the placebo-treated group. No differences in adverse events were noted between groups.

CONCLUSION

High-dose iron dextran infusion is associated with a significant, but transient, reduction in symptoms of RLS in patients with ESRD.