Evidence continues to mount on the relationship of restless legs syndrome/ periodic limb movements in sleep to hypertension, cardiovascular disease, and stroke

Usefulness of Restless Legs Symptoms to Predict Adverse Cardiovascular Outcomes in Men With Coronary Artery Disease

The relationship between restless legs syndrome (RLS) and cardiovascular disease remains enigmatic in the general population, and its prognostic value in patients with coronary artery disease (CAD) is unknown. In this study, the frequency of RLS-like symptoms was assessed using a validated instrument in 3,266 patients undergoing cardiac catheterization (mean age 64 years, 62% male, 23% Black, and 74% with obstructive CAD). Patients were followed for primary end points of cardiovascular death or incident myocardial infarction. Fine and Gray hazard models explored the association between RLS and incident events after adjustment for demographic and clinical risk factors. In the total cohort, 29% of patients reported mild (rare or sometimes) symptoms, and 15% of patients had moderate/severe (often to almost always) symptoms of RLS. Female sex (odds ratio [OR] 2.11, 95% confidence interval (CI), 1.68 to 2.57), body mass index (OR 1.12 per 5 kg/m², 95% CI, 1.04 to 1.22), diabetes (OR 1.43, 95%,1.15 to 1.79), and β-blocker use (OR 1.35, 95% CI, 1.07 to 1.72) were independently associated with moderate/severe symptoms of RLS compared with no symptoms. Over a 5-year follow-up period, 991 patients suffered an adverse event. Compared with those with no symptoms, patients with moderate/severe RLS had significantly higher risk of the primary end point (hazard ratio [HR] = 1.33, 95%),CI 1.01 to 1.76) after adjustment for demographic and clinical risk factors. The association was more significant in men than women, HR 1.98, 95% CI, 1.41 to 2.78 versus HR 0.99 (,95% CI, 0.64 to 1.52, p interaction= 0.013. In conclusion, among men with CAD, moderate-to-severe symptoms of RLS are associated with significantly higher risk of adverse cardiovascular outcomes, independent of traditional risk factors.

Cardiac Involvement in Movement Disorders

Background

Several conditions represented mainly by movement disorders are associated with cardiac disease, which can be overlooked in clinical practice in the context of a prominent primary neurological disorder.

Objectives

To review neurological conditions that combine movement disorders and primary cardiac involvement.

Methods

A comprehensive and structured literature search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria was conducted to identify disorders combining movement disorders and cardiac disease.

Results

Some movement disorders are commonly or prominently associated with cardiac disease. Neurological and cardiac symptoms may share underlying physiopathological mechanisms in diseases, such as Friedreich's ataxia and Wilson's disease, and in certain metabolic disorders, including Refsum disease, Gaucher disease, a congenital disorder of glycosylation, or cerebrotendinous xanthomatosis. In certain conditions, such as Sydenham's chorea or dilated cardiomyopathy with ataxia syndrome (ATX-DNAJC19), heart involvement can present early in the course of disease, whereas in others such as Friedreich's ataxia or Refsum disease, cardiac symptoms tend to present in later stages. In another 68 acquired or inherited conditions, cardiac involvement or movement disorders are seldom reported.

Conclusions

As cardiac disease is part of the phenotypic spectrum of several movement disorders, heart involvement should be carefully investigated and increased awareness of this association encouraged as it may represent a leading cause of morbidity and mortality.

Emerging Concepts of the Pathophysiology and Adverse Outcomes of Restless Legs Syndrome

Restless legs syndrome (RLS), also known as Willis-Ekbom disease (WED), is a common neurological disorder affecting up to 5% to 10% of the population, but it remains an underdiagnosed condition. RLS/WED is characterized by uncomfortable sensations, mainly in the legs, which appear during inactivity and worsen in the evening or at night. The prevalence of RLS/WED and periodic leg movements (PLMs) is increased in patients with sleep-disordered breathing, particularly in those with OSA, the most common sleep disorder encountered in sleep centers. New advances in the pathophysiology of RLS/WED have shown important implications for various genetic markers, neurotransmitter dysfunction, and iron deficiency. A practical approach to RLS/WED management includes an accurate diagnosis, the identification of reversible contributing factors, and the use of nonpharmacological therapies, including iron substitution (oral or IV) therapy. Many pharmacological agents are effective for the treatment of RLS/WED. Until recently, the first-line treatment of RLS/WED consisted of low-dose dopamine agonists (DA). However, given the fact that DAs cause high rates of augmentation of symptoms, international guidelines recommend that whenever possible the initial treatment of choice should be an α2δ ligand, and avoidance of dopaminergic agents unless absolutely necessary. If necessary, the lowest effective dose should be used for only the shortest possible time. The symptoms of RLS/WED can disrupt the quality of sleep as well as the quality of life. IV iron therapy may be considered in patients with refractory RLS. A better understanding of RLS/WED pathophysiology will allow patients to receive tailored therapy, resulting in an improved quality of life.

Correlates and predictors of paediatric leg pain: a case-control study

Paediatric leg pains, long described as 'growing pains', frequently present to clinicians, are prevalent in early childhood, disrupt sleep, and distress affected children and parents. There are many cited associations, but no defined leg pain sub-types, nor revealed predictive factors. We explored the implicated factors (viz. foot arches, foot strength, joint mobility, vitamin D, iron) in children with leg pain versus a control group. Leg pain sub-groups-growing pains (GP), restless legs (RLS), both (mixed)-are defined for the first time. A case controlled study design, in a primary care setting, Mumbai, India. A total of 77 children with leg pains (n = 64) and controls (n = 13), aged 3-12 years, identified by paediatricians, completed data collection. Blood assays for iron and vitamin D, pain, Beighton score, foot arch, foot strength and anthropometrical data were collected. All outcome measures were validated, with standardised protocols. Leg pain (all groups) was predicted by increased joint mobility and increased ankle dorsiflexion strength (β = 0.56, P < 0.05). GP sub-group was predicted by increased ankle dorsiflexion strength (β = - 0.06, P < 0.05). Mixed (GP/RLS) and RLS sub-groups were predicted by increased ankle dorsiflexion strength (β = 0.66, P < 0.05) and pain questionnaire (β = 0.11, P < 0.05). Hypovitaminosis D was detected in 87% of the sample, and anaemia in 13%. Increased strength of ankle dorsiflexors and joint flexibility were each found predictive for leg pain. Increased body weight, waist girth, and BMI were all associated with leg pain.

Association of restless legs syndrome and mortality in end-stage renal disease: an analysis of the United States Renal Data System (USRDS)

Background

Objective of the study is to assess prevalence and survival among end stage renal disease patients with restless legs syndrome (RLS) within a national database (USRDS).

Methods

A case-control, retrospective analysis was performed. Differences in characteristics between the groups, RLS and those with no sleep disorder (NSD), were determined using χ2 tests. Cox proportional hazard regression was used to assess survival between those with RLS and propensity score matched controls.

Results

Cases of restless legs syndrome were defined as patients that had received an ICD-9 code of 333.94 at any point during their treatment (n = 372). RLS group demonstrated a significantly higher proportion of patients with major depressive disorder, dysthymic disorder, anxiety, depression, minor depressive disorder, and psychological disorder. The difference between the survival was not statistically significant in those without sleep disorder as compared to those with RLS (HR =1.16±0.14, p = 0.3).

Conclusions

True prevalence of RLS in dialysis patients can only be estimated if knowledge gap for care providers in diagnosis of RLS is addressed. RLS patients also have increased incidence of certain psychological disorders which needs to be addressed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0660-0) contains supplementary material, which is available to authorized users.

The Clinical Importance of Periodic Leg Movements in Sleep

OPINION STATEMENT

Periodic leg movements during sleep (PLMS) are commonly found in patients with restless leg syndrome (RLS), but they may occur in other sleep disorders and several medical conditions. Their prevalence increases with age, but they can also be observed in children. During the last decades, very active research has been devoted to determine and understand the pathophysiology, associated events, and clinical significance of PLMS. This chapter tries to sum up the most relevant PLMS-related findings, focusing on the relationship between PLMS and the cardiovascular system, in order to understand the clinical implication of this complex motor phenomenon. PLMS have been associated with sympathetic overactivity, namely surges in nocturnal blood pressure and heart rate, without modification in global autonomic balance. Also, PLMS have been related to inflammatory cellular pathways, with elevated level of inflammatory markers, which are associated with cardiovascular risk. The PLMS-related modulation of the autonomic system and of inflammation may increase cardiovascular and cerebrovascular risk in subjects with frequent PLMS. Moreover, also, comorbidities associated with PLMS may play a synergic role in worsening the cardiovascular risk and the consequent mortality and morbidity. Furthermore, little is known about pathophysiological correlates in children with PLMS and their chronic implication on the cardiovascular and cerebrovascular systems. A few studies have suggested that treating PLMS with dopaminergic drugs may reduce their associated sympathetic overactivity and modify disease progression. Definitely, further research is needed to assess the clinical impact of PLMS, associated or not with RLS, and above all the long-term impact of treating PLMS on cardiovascular risk, morbidity, and mortality.

Interventions for chronic kidney disease-associated restless legs syndrome

BACKGROUND

Restless legs syndrome (RLS) is defined as the spontaneous movement of the limbs (mainly legs) associated with unpleasant, sometimes painful sensation which is relieved by moving the affected limb. Prevalence of RLS among people on dialysis has been estimated between 6.6% and 80%. RLS symptoms contribute to impaired quality of life and people with RLS are shown to have increased cardiovascular morbidity and mortality.Various pharmacological and non-pharmacological interventions have been used to treat primary RLS. However, the evidence for use of these interventions in people with chronic kidney disease (CKD) is not well established. The agents used in the treatment of primary RLS may be limited by the side effects in people with CKD due to increased comorbidity and altered drug pharmacokinetics.

OBJECTIVES

The aim of this review was to critically look at the benefits, efficacy and safety of various treatment options used in the treatment of RLS in people with CKD and those undergoing renal replacement therapy (RRT). We aimed to define different group characteristics based on CKD stage to assess the applicability of a particular intervention to an individual patient.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 12 January 2016 through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCT) and quasi-RCTs that assessed the efficacy of an intervention for RLS in adults with CKD were eligible for inclusion. Studies investigating idiopathic RLS or RLS secondary to other causes were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for eligibility and conducted risk of bias evaluation. Results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes.

MAIN RESULTS

We included nine studies enrolling 220 dialysis participants. Seven studies were deemed to have moderate to high risk of bias. All studies were small in size and had a short follow-up period (two to six months). Studies evaluated the effects of six different interventions against placebo or standard treatment. The interventions studied included aerobic resistance exercise, gabapentin, ropinirole, levodopa, iron dextran, and vitamins C and E (individually and in combination).Aerobic resistance exercise showed a significant reduction in severity of RLS compared to no exercise (2 studies, 48 participants: MD -7.56, 95% CI -14.20 to -0.93; I2 = 65%), and when compared to exercise with no resistance (1 study, 24 participants: MD -11.10, 95% CI -17.11 to -5.09), however there was no significant reduction when compared to ropinirole (1 study, 22 participants): MD -0.55, 95% CI -6.41 to 5.31). There were no significant differences between aerobic resistance exercise and either no exercise or ropinirole in the physical or mental component summary scores (using the SF-36 form). Improvement in sleep quality varied. There was no significant difference in subjective sleep quality between exercise and no exercise; however one study reported a significant improvement with ropinirole compared to resistance exercise (MD 3.71, 95% CI 0.89 to 6.53). Using the Epworth Sleepiness Scale there were no significant differences between resistance exercise and no exercise, ropinirole, or exercise with no resistance. Two studies reported there were no adverse events and one study did not mention if there were any adverse events. In one study, one patient in each group dropped out but the reason for dropout was not reported. Two studies reported no adverse events and one study did not report adverse events.Gabapentin was associated with reduced RLS severity when compared to placebo or levodopa, and there was a significant improvement in sleep quality, latency and disturbance reported in one study when compared to levodopa. Three patients dropped out due to lethargy (2 patients), and drowsiness, syncope and fatigue (1 patient).Because of a short duration of action, rebound and augmentation were noted with levodopa treatment even though it conferred some benefit in reducing the symptoms of RLS. Reported adverse events were severe vomiting, agitation after caffeine intake, headaches, dry mouth, and gastrointestinal symptoms.One study (25 participants) reported iron dextran reduced the severity of RLS at weeks one and two, but not at week four. Vitamins C, E and C plus E (1 study, 60 participants) helped the symptoms of RLS with minimal side effects (nausea and dyspepsia) but more evidence is needed before any conclusions can be drawn.

AUTHORS' CONCLUSIONS

Given the small size of the studies and short follow-up, it can only be concluded that pharmacological interventions and intra-dialytic exercise programs have uncertain effects on RLS in haemodialysis patients. There have been no studies performed in non-dialysis CKD, peritoneal dialysis patients, or kidney transplant recipients. Further studies are warranted before any conclusions can be drawn. Aerobic resistance exercise and ropinirole may be suitable interventions for further evaluation.

Nonnegative matrix factorization and sparse representation for the automated detection of periodic limb movements in sleep

Stroke is a leading cause of death and disability in adults, and incurs a significant economic burden to society. Periodic limb movements (PLMs) in sleep are repetitive movements involving the great toe, ankle, and hip. Evolving evidence suggests that PLMs may be associated with high blood pressure and stroke, but this relationship remains underexplored. Several issues limit the study of PLMs including the need to manually score them, which is time-consuming and costly. For this reason, we developed a novel automated method for nocturnal PLM detection, which was shown to be correlated with (a) the manually scored PLM index on polysomnography, and (b) white matter hyperintensities on brain imaging, which have been demonstrated to be associated with PLMs. Our proposed algorithm consists of three main stages: (1) representing the signal in the time-frequency plane using time-frequency matrices (TFM), (2) applying K-nonnegative matrix factorization technique to decompose the TFM matrix into its significant components, and (3) applying kernel sparse representation for classification (KSRC) to the decomposed signal. Our approach was applied to a dataset that consisted of 65 subjects who underwent polysomnography. An overall classification of 97 % was achieved for discrimination of the aforementioned signals, demonstrating the potential of the presented method.

Achievements, challenges, and future perspectives of epidemiologic research in restless legs syndrome (RLS)

In the 20 years since the initial consensus on a common definition for restless legs syndrome (RLS), over 600 scientific reports on epidemiological aspects of RLS have been published. Most are descriptive and address important issues such as prevalence, familial patterns, comorbidities, and quality of life. While the establishment of prospective cohort studies and the use of secondary data sources are rather new to RLS research, both options significantly broaden the possibilities for analysis of disease risk factors. These two options, as well as the inclusion of a broader phenotyping of individual patients, have great potential to elucidate etiologic factors for RLS and expand knowledge about this common disorder. This article summarizes achievements in the area of RLS epidemiology, describes current challenges, and highlights future perspectives in the field.

Silent Cerebral Small Vessel Disease in Restless Legs Syndrome

STUDY OBJECTIVES

Growing literature suggests that patients with restless legs syndrome (RLS) may be at increased risk for hypertension, heart disease, and stroke. Cerebral small vessel disease (SVD) is a known risk factor for clinical stroke. This study evaluated silent cerebral SVD by MRI in patients with RLS, in the absence of a history of previous clinical stroke or known stroke risk factors and taking into account disease duration.

METHODS

Fifty-three patients with RLS < 10 y were prospectively recruited along with 44 with RLS > 10 y and 74 normal controls. A magnetic resonance imaging study was obtained from all subjects and scans were analyzed for area and volume of SVD.

RESULTS

There was a significant increase in SVD area in the entire group of RLS patients compared to controls (P = 0.036); this was almost entirely driven by the group with RLS > 10 y. SVD area and volume were significantly increased in patients with RLS > 10 y with respect to both controls (P < 0.0001 and P < 0.0014, respectively) and RLS < 10 y (P < 0.00022 and P < 0.003, respectively). Age, duration of RLS, and the interaction of age and duration of RLS were independent predictors of SVD disease. Duration of RLS was an independent predictor of the burden of cerebral SVD (area P < 0.00012 and volume P < 0.0025), whereas sex and insomnia were not.

CONCLUSION

RLS duration should be taken into account when analyzing the association between RLS and cerebrovascular disease; our data support the hypothesis that a long-lasting RLS and its accompanying periodic limb movements in sleep are a risk factor for silent SVD and perhaps for the development of clinical stroke.

Restless Legs Symptoms and Pregnancy and Neonatal Outcomes

PURPOSE

Restless legs syndrome (RLS) is a commonly occurring neurologic disorder that affects up to one third of women during pregnancy. RLS has been associated with increased sympathetic tone in the nonpregnant population. We examined whether a RLS surrogate is associated with a higher prevalence of pregnancy and neonatal outcomes.

METHODS

Data were analyzed from a cross-sectional survey of 1000 women interviewed soon after delivery by using an RLS surrogate question. Women were asked how frequently (0 = none, 1 = rarely [<1 time/week], 2 = sometimes [1-2 times/week], 3 = frequently [3-4 times/week], and 4 = always [5-7 times/week]) they had "experienced jumpy or jerky leg movements" in the last 3 months of pregnancy. Clinical charts were reviewed to obtain relevant demographic and clinical data, including the presence of gestational hypertensive disorders and neonatal outcomes at birth. Subjects who "always" experienced RLS were compared with subjects experiencing symptoms less frequently or not at all with respect to prevalence of gestational hypertensive disorder.

FINDINGS

The mean ([SD]) age, prepregnancy body mass index (BMI), and BMI at delivery were 29.0 (6.1) years, 26.1 (6.2) kg/m(2), and 32.0 (6.3) kg/m(2), respectively. The overall prevalence of the RLS surrogate (jumpy or jerky leg movements) was 35.5% with the following distribution on a Likert scale: score 1 = 6.4%; score 2 = 10.2%; score 3 = 8.1%; and score 4 = 10.8%. Chronic hypertension was present in 2.1%, pregnancy-induced hypertension in 9.5%, and preeclampsia in 4.5% of respondents. Subjects who reported "always" having sensations of jumpy or jerky legs were more likely to have gestational hypertensive disorders compared with those who reported less frequent occurrence of the symptoms. Adjusted odds ratios were 3.74 (95% CI, 1.31-10.72; P = 0.014) for chronic hypertension; 1.26 (95% CI, 0.65-2.46; P = 0.487) for pregnancy-induced hypertension; and 2.15 (95% CI, 0.97-4.75; P = 0.060) for preeclampsia. There was a significant association between leg movement score and neonatal birth weight (coefficient, -149.5 g [95% CI, -276.9 to -22.5]; P = 0.005) and gestational age at birth (-0.7 week [95% CI, -1.1 to -0.2]; P = 0.021) that persisted after adjusting for preeclampsia, diabetes, and smoking.

IMPLICATIONS

A higher frequency of jumpy or jerky leg symptoms, a proxy for RLS during pregnancy, was associated with a higher likelihood of gestational hypertensive disorders and neonatal outcomes such as gestational age at birth and birth weight. These findings may affect RLS treatment decisions during pregnancy.

Restless Legs Syndrome: Associated Risk Factors in Hemodialysis Patients

Background:

Restless legs syndrome (RLS) may be associated with increased morbidity and mortality among end-stage renal disease (ESRD) patients; however, it is a disorder that is neglected in dialysis centers.

Objectives:

The goal of this study was to investigate the clinical factors associated with RLS among ESRD patients.

Patients and Methods:

This cross-sectional study was conducted on ESRD patients undergoing maintenance hemodialysis (HD) in three HD centers in Ahvaz city in Southwest Iran. Blood samples were obtained prior to a dialysis session to check the routine laboratory test results and assess the adequacy of dialysis. The presence of RLS was assessed by using the international RLS study group (IRLSSG) diagnostic criteria. The IRLSSG rating scale was also used to evaluate the severity of the RLS symptoms.

Results:

Of the 139 HD patients enrolled in this study, 60 were female (43.2%) and 79 were male (56.8%), with a mean age of 51.82 ± 13.31 years. The prevalence of RLS was 15.8% (22 patients), with 50% of them (11 patients) having severe or very severe symptoms. There was a significant relationship between RLS and longer durations of dialysis (P < 0.001). The mean level of serum ferritin was lower in patients without RLS, but it was not significant (P = 0.065). No significant differences were found according to age, gender, dialysis shifts, and hemoglobin (Hb) level among patients with and without RLS.

Conclusions:

We conclude that a significant percentage of ESRD patients undergoing maintenance HD have severe or very severe RLS symptoms. The presence of RLS is associated to longer durations of dialysis.

Restless legs syndrome, a predictor of subcortical stroke: a prospective study in 346 stroke patients

OBJECTIVE

The objective of this study was to assess the prevalence of restless legs syndrome (RLS) among patients with stroke and to examine the anatomical correlation between location of stroke and RLS symptoms.

METHODS

We administered a pre-structured sleep questionnaire to consecutive stroke patients seen in our neurology services department over a 3-year period. Unconscious (Glasgow Coma Scale score <15) or aphasic, renally impaired, or neuropathic patients were excluded. Diagnosis of RLS was established according to the criteria of the International Restless Legs Syndrome Study Group (IRLSSG), and polysomnography was conducted.

RESULTS

Of 346 stroke patients, 35 (10.11%) fulfilled IRLSSG diagnostic criteria for RLS, which had existed for an average (±standard deviation) of 60 ± 40 months before stroke. The mean age of onset was 52.94 (±10.32) years. Twenty-four patients (68%) had RLS symptoms contralateral to the hemisphere involved in the stroke (eight with unilateral and 16 with grossly asymmetrical RLS). Twenty-nine of 35 patients (82.86%) had imaging evidence of subcortical (16 with hemorrhagic and 13 with ischemic) stroke. Patients with pre-stroke RLS differed from those without it only by subcortical location of the stroke (82.9% vs 31.5% respectively, p < 0.001). The most significant differentiating factor between patients with subcortical stroke and those with cortical stroke was pre-stroke RLS (22.83% vs 2.74%, p < 0.001), the others being history of hypertension and hemorrhagic stroke type.

CONCLUSION

RLS, especially unilateral or asymmetrical, might frequently pre-exist in patients presenting with subcortical stroke. The common laterality may suggest an important predictive value for RLS, and may form an important point for future research.

An Evidence-based Analysis of the Association between Periodic Leg Movements during Sleep and Arousals in Restless Legs Syndrome

STUDY OBJECTIVES

To analyze statistically the association between periodic leg movements during sleep (PLMS) and arousals, in order to eventually support or challenge the current scoring rules and to further understand their reciprocal influence.

SETTING

Sleep research center.

PATIENTS

Twenty untreated consecutive patients with restless legs syndrome (RLS) (13 women and 7 males, mean age 60.9 y).

METHODS

In each recording, we selected all PLMS/arousal pairs that met the following inclusion criteria: (a) PLMS events that were separated from another PLMS event (preceding or following) by at least 10 s of EMG inactivity; (b) arousal events separated from another arousal event (preceding or following) by at least 10 s of stable EEG baseline activity; (c) PLMS/arousal pairs were then selected among events identified according to the previous two criteria, when PLMS and arousals were separated (offset-to-onset) by no more than 10 s, regardless of which was first.

MEASUREMENTS AND RESULTS

We selected a mean of 46.1 (SD 25.55) PLMS/arousal pairs per subject; in these pairs, average PLMS duration was 3.2 s (0.65) and average arousal duration was 6.5 s (0.92). Within these event pairs, the great majority (on average 98.4%, SD 3.88) was separated by less than 0.5 s (i.e., between the end of one event and the onset of the other, regardless of which was first). Arousal onsets preceded PLMS onset in 41.2% of pairs, while the opposite was true for the remaining 58.8% of pairs. A significant correlation between PLMS duration and arousal duration was also found (r = 0.447, P < 0.000001).

CONCLUSION

The results of this study support the current rule for the definition of the association between periodic leg movements during sleep (PLMS) and arousals. The tight time relationship between PLMS and arousals and their correlated durations seem to indicate that both events might be regulated by a complex mechanism, rather than being connected by a simple reciprocal cause/effect relationship.

An update on restless legs syndrome (Willis-Ekbom disease): clinical features, pathogenesis and treatment

PURPOSE OF REVIEW

In recent years, there have been a number of advances in the field of restless legs syndrome (RLS) or Willis-Ekbom disease (WED). Here, we review recent studies pertaining to the diagnosis and clinical features, pathogenesis, and treatment of RLS/WED.

RECENT FINDINGS

Recent studies have added a temporal dimension to RLS/WED epidemiology by examining both the incidence and persistence rates in different populations. Diagnostic criteria have been modified to increase sensitivity, and new guidelines take into account recently published studies of different drug classes.

SUMMARY

Recent epidemiological findings have shown that RLS/WED is a common neurological disorder that affects up to 5% of the adult population in Western countries. In moderate and severe cases, RLS/WED has a strong impact on sleep and quality of life and can involve an increased cardiovascular risk. Diagnosis is made clinically by confirming the presence of the five essential criteria. However, in difficult cases objective tests such as the multiple suggested immobilization test (m-SIT) can be used. The pathophysiology is partially known, with several risk polymorphisms (BTBD-9 (BTB (POZ) domain containing 9), MEIS-1 (Meis homeobox 1), protein tyrosine phosphatase, receptor type, D, and others) playing an important role, along with dopaminergic and iron dysfunctions. The disorder frequently requires long-term treatment with low-dose dopamine agonists or α2δ ligands. Dopamine agonists are usually effective but the main complication, RLS/WED augmentation, can arise.

Restless Legs Syndrome: Would You Like That with Movements or Without?

The restless legs syndrome (RLS) is a common sensorimotor condition that often results in discomfort and sleep disturbance. Diagnosis of RLS is entirely clinical and based upon a patient's description of subjective symptoms, and thus when considering RLS diagnosis non-specificity is a real problem. RLS is associated with periodic limb movements during sleep (PLMS) in up to 90% of RLS sufferers; however, their presence is neither sufficient nor necessary for the diagnosis of RLS. The disease RLS and the motor phenomenon of PLMS share similarities in various areas, which include pathophysiology, pharmacology, genetics, and epidemiology. The purpose of this opinion piece is to outline the many similarities between RLS and PLMS in order to make an argument for the inclusion of PLMS as a supplementary diagnostic criterion of RLS, termed electro-clinical RLS, which would consist of the current clinical RLS diagnosis plus PLMS. This additional criterion could be used in cases where diagnosis is unclear to increase specificity or in research projects where proper diagnosis is desired at the investigational level.

Restless legs syndrome/Willis-Ekbom disease diagnostic criteria: updated International Restless Legs Syndrome Study Group (IRLSSG) consensus criteria--history, rationale, description, and significance

BACKGROUND

In 2003, following a workshop at the National Institutes of Health, the International Restless Legs Syndrome Study Group (IRLSSG) developed updated diagnostic criteria for restless legs syndrome/Willis-Ekbom disease (RLS/WED). These criteria were integral to major advances in research, notably in epidemiology, biology, and treatment of RLS/WED. However, extensive review of accumulating literature based on the 2003 NIH/IRLSSG criteria led to efforts to improve the diagnostic criteria further.

METHODS

The clinical standards workshop, sponsored by the WED Foundation and IRLSSG in 2008, started a four-year process for updating the diagnostic criteria. That process included a rigorous review of research advances and input from clinical experts across multiple disciplines. After broad consensus was attained, the criteria were formally approved by the IRLSSG executive committee and membership.

RESULTS

Major changes are: (i) addition of a fifth essential criterion, differential diagnosis, to improve specificity by requiring that RLS/WED symptoms not be confused with similar symptoms from other conditions; (ii) addition of a specifier to delineate clinically significant RLS/WED; (iii) addition of course specifiers to classify RLS/WED as chronic-persistent or intermittent; and (iv) merging of the pediatric with the adult diagnostic criteria. Also discussed are supportive features and clinical aspects that are important in the diagnostic evaluation.

CONCLUSIONS

The IRLSSG consensus criteria for RLS/WED represent an international, interdisciplinary, and collaborative effort intended to improve clinical practice and promote further research.

Restless leg syndrome in diabetics compared with normal controls

Introduction. Restless leg syndrome (RLS) is a common sleep disorder which is characterized by urge to move the legs accompanied by disturbing and uncomfortable leg sensation during night and rest. This common condition affects 7–10% of general population and is frequently unrecognized, misdiagnosed, and poorly managed. Several clinical conditions like diabetes have been associated with secondary form of RLS. This study analyzed the frequency and possible risk factor for RLS development in diabetic patient. Material and Methods. This descriptive case-control study was done on 140 consecutive outpatient diabetics and age, sex, and body mass index matched control group. RLS was diagnosed by criteria of the International RLS Study Group. Results. Prevalence of RLS was 28.6% in diabetes and 7.1% in control group (P = 0.001). Sex difference was not significant and with rising duration of diabetes prevalence of RLS was not increased. Discussion. With regarding significant association between RLS and diabetes and its negative impact on quality of life/health outcome/sleep/daytime activity/cognitive function/ and mental state of diabetic patient/higher awareness of RLS among physicians and related health worker suggested.

Obstructive sleep apnea and risk of cardiovascular events and all-cause mortality: a decade-long historical cohort study

BACKGROUND

Obstructive sleep apnea (OSA) has been reported to be a risk factor for cardiovascular (CV) disease. Although the apnea-hypopnea index (AHI) is the most commonly used measure of OSA, other less well studied OSA-related variables may be more pathophysiologically relevant and offer better prediction. The objective of this study was to evaluate the relationship between OSA-related variables and risk of CV events.

METHODS AND FINDINGS

A historical cohort study was conducted using clinical database and health administrative data. Adults referred for suspected OSA who underwent diagnostic polysomnography at the sleep laboratory at St Michael's Hospital (Toronto, Canada) between 1994 and 2010 were followed through provincial health administrative data (Ontario, Canada) until May 2011 to examine the occurrence of a composite outcome (myocardial infarction, stroke, congestive heart failure, revascularization procedures, or death from any cause). Cox regression models were used to investigate the association between baseline OSA-related variables and composite outcome controlling for traditional risk factors. The results were expressed as hazard ratios (HRs) and 95% CIs; for continuous variables, HRs compare the 75th and 25th percentiles. Over a median follow-up of 68 months, 1,172 (11.5%) of 10,149 participants experienced our composite outcome. In a fully adjusted model, other than AHI OSA-related variables were significant independent predictors: time spent with oxygen saturation <90% (9 minutes versus 0; HR = 1.50, 95% CI 1.25-1.79), sleep time (4.9 versus 6.4 hours; HR = 1.20, 95% CI 1.12-1.27), awakenings (35 versus 18; HR = 1.06, 95% CI 1.02-1.10), periodic leg movements (13 versus 0/hour; HR = 1.05, 95% CI 1.03-1.07), heart rate (70 versus 56 beats per minute [bpm]; HR = 1.28, 95% CI 1.19-1.37), and daytime sleepiness (HR = 1.13, 95% CI 1.01-1.28).The main study limitation was lack of information about continuous positive airway pressure (CPAP) adherence.

CONCLUSION

OSA-related factors other than AHI were shown as important predictors of composite CV outcome and should be considered in future studies and clinical practice.

Sleep-Wake Cycle and Daytime Sleepiness in the Myotonic Dystrophies

Myotonic dystrophy is the most common type of muscular dystrophy in adults and is characterized by progressive myopathy, myotonia, and multiorgan involvement. Two genetically distinct entities have been identified, myotonic dystrophy type 1 (DM1 or Steinert's Disease) and myotonic dystrophy type 2 (DM2). Myotonic dystrophies are strongly associated with sleep dysfunction. Sleep disturbances in DM1 are common and include sleep-disordered breathing (SDB), periodic limb movements (PLMS), central hypersomnia, and REM sleep dysregulation (high REM density and narcoleptic-like phenotype). Interestingly, drowsiness in DM1 seems to be due to a central dysfunction of sleep-wake regulation more than SDB. To date, little is known regarding the occurrence of sleep disorders in DM2. SDB (obstructive and central apnoea), REM sleep without atonia, and restless legs syndrome have been described. Further polysomnographic, controlled studies are strongly needed, particularly in DM2, in order to clarify the role of sleep disorders in the myotonic dystrophies.

Frequent periodic leg movement during sleep is associated with left ventricular hypertrophy and adverse cardiovascular outcomes

BACKGROUND

Sleep disturbance caused by obstructive sleep apnea is recognized as a contributing factor to adverse cardiovascular outcomes. However, the effect of restless legs syndrome, another common cause of fragmented sleep, on cardiac structure, function, and long-term outcomes is not known. The aim of this study was to assess the effect of frequent leg movement during sleep on cardiac structure and outcomes in patients with restless legs syndrome.

METHODS

In our retrospective study, patients with restless legs syndrome referred for polysomnography were divided into those with frequent (periodic movement index > 35/hour) and infrequent (≤ 35/hour) leg movement during sleep. Long-term outcomes were determined using Kaplan-Meier and logistic regression models.

RESULTS

Of 584 patients, 47% had a periodic movement index > 35/hour. Despite similarly preserved left ventricular ejection fraction, the group with periodic movement index > 35/hour had significantly higher left ventricular mass and mass index, reflective of left ventricular hypertrophy (LVH). There were no significant baseline differences in the proportion of patients with hypertension, diabetes, hyperlipidemia, prior myocardial infarction, stroke or heart failure, or the use of antihypertensive medications between the groups. Patients with frequent periodic movement index were older, predominantly male, and had more prevalent coronary artery disease and atrial fibrillation. However, on multivariate analysis, periodic movement index > 35/hour remained the strongest predictor of LVH (odds ratio, 2.45; 95% confidence interval, 1.67-3.59; P < .001). Advanced age, female sex, and apnea-hypopnea index were other predictors of LVH. Patients with periodic movement index > 35/hour had significantly higher rates of heart failure and mortality over median 33-month follow-up.

CONCLUSIONS

Frequent periodic leg movement during sleep is an independent predictor of severe LVH and is associated with increased cardiovascular morbidity and mortality.

Experimentally induced arousals do not elicit periodic leg motor activity during sleep in normal subjects

OBJECTIVE

To evaluate whether eliciting repetitive cortical and autonomic arousals during sleep is able to induce the occurrence of periodic leg movements during sleep (PLMS).

METHODS

Fifteen normal subjects underwent one night of uninterrupted and two sequential nights of experimental sleep fragmentation achieved by auditory and mechanical stimuli eliciting frequent EEG arousals. Sleep was polygraphically recorded and subsequently used to determine the frequency of arousals and occurrence of leg movement (LM) activity during the first (baseline) and the second fragmentation night. Also, heart rate variability parameters were obtained to assess the autonomic changes induced by the stimulation.

RESULTS

Sleep fragmentation was associated with an increase in the arousal index, percentage of sleep stage 1, and frequency of stage shifts. In addition, there was a decrease in sleep latency and in percentage of slow-wave sleep. Moreover, a significant increase in heart rate variability and especially of its sympathetic component, was also found. In contrast, parameters of the leg movement activity showed no significant change following experimental sleep fragmentation. The lack of an increase in leg movement activity was also observed in one subject who demonstrated PLMS at baseline.

CONCLUSIONS

Experimental sleep fragmentation is not associated with an increase in PLMS in normal young adults.

Capturing PLMS and their variability in children with sickle cell disease: does ankle activity monitoring measure up to polysomnography?

OBJECTIVES

To test agreement and define differences in periodic limb movements in sleep (PLMS) measured by polysomnography and an ankle activity monitor, and to describe PLMS variability across nights, feasibility of home monitoring, and correlates of PLMS in children with sickle cell disease (SCD).

METHODS

Twenty children with SCD and restless legs syndrome (RLS) symptoms or polysomnography-documented PLMS underwent concurrent attended polysomnography and ankle activity monitoring over one to two nights and home activity monitoring for three nights. Serum iron and ferritin were measured pre- and post-polysomnography.

RESULTS

Adequate sensitivity (1.00), specificity (0.69), and mean bias (5.0±7.4 PLMS/h) for identifying elevated PLMS by activity monitor were obtained when scoring the period from sleep onset to offset rather than time in bed per manufacturer recommendation, and using a cut-point of 10 PLMS/h. Compared to activity monitor, only polysomnographic PLMS demonstrated periodicity, at inter-movement intervals (IMI) 20-35 s; the activity monitor overscored PLMS at the beginning and end of sleep and at shorter IMI (5-15s; p≤0.003), suggesting misclassification of nonperiodic leg movements as PLMS by activity monitor. PLMS varied across four nights by 16.1±13.4 PLMS/h. Post-polysomnography ferritin was associated (positively) with PLMS (p=0.034); RLS symptoms were not.

CONCLUSIONS

Ankle activity monitoring is a valid screening measure for PLMS in children with SCD and can readily be performed at home. Interpretation should incorporate a threshold for elevated PLMS of 10/h and scoring from sleep onset to offset, which could be identified with concurrent wrist actigraphy, to better account for true PLMS.

Neurological disorders: towards a mechanistic understanding of restless legs syndrome

Restless legs syndrome is a curious neurological disorder of unknown aetiology. A new study has found that Drosophila mutants in the fly homologue of a human gene, BTBD9, that has been implicated as a risk factor for restless legs display important features of the syndrome.

Absence of cardiovascular disease risk factors in restless legs syndrome

OBJECTIVE

Restless legs syndrome (RLS) might represent a condition at risk of cardiovascular (and cerebrovascular) disease; the role of sleep periodic leg movements, sleep deprivation, and presence of common risk factors for heart disease in these patients remains to be determined. The aim of this study was to evaluate the eventual presence of risk factors for cerebrovascular disease in RLS.

MATERIALS & METHODS

Eighty-seven consecutive patients affected by idiopathic RLS were included in this study together with 81 controls. Blood count, chemistry, and kidney function tests were obtained. We detected subjects suffering from diabetes mellitus, kidney diseases, heart diseases, disk herniation, neuropathy, blood diseases, liver diseases, artery diseases, dyslipidemia, or hypertension. Polysomnography was recorded in 66 patients, and cerebral neuroimaging was obtained in 59 patients with RLS.

RESULTS

None of the differences in blood test parameters was statistically significant; however, hypertension was found to be more frequent in controls and dyslipidemia was more frequent in patients with RLS, but this was explained by its higher frequency in patients also affected by obstructive sleep apnea. A diagnosis of cerebrovascular disease was posed for 14 patients with RLS (16.1%), but no predictive factor for its presence was found at the binomial logistic regression.

CONCLUSION

Our findings argue against the presence of an altered lipid metabolism as a risk factor for the development of cerebrovascular disease in patients with RLS, even if they do support the idea that cerebrovascular disease might be frequent in this condition.

Myotonic dystrophy type 1, daytime sleepiness and REM sleep dysregulation

Myotonic dystrophy type 1 (DM1), or Steinert's disease, is the most common adult-onset form of muscular dystrophy. DM1 also constitutes the neuromuscular condition with the most significant sleep disorders including excessive daytime sleepiness (EDS), central and obstructive sleep apneas, restless legs syndrome (RLS), periodic leg movements in wake (PLMW) and periodic leg movements in sleep (PLMS) as well as nocturnal and diurnal rapid eye movement (REM) sleep dysregulation. EDS is the most frequent non-muscular complaint in DM1, being present in about 70-80% of patients. Different phenotypes of sleep-related problems may mimic several sleep disorders, including idiopathic hypersomnia, narcolepsy without cataplexy, sleep apnea syndrome, and periodic leg movement disorder. Subjective and objective daytime sleepiness may be associated with the degree of muscular impairment. However, available evidence suggests that DM1-related EDS is primarily caused by a central dysfunction of sleep regulation rather than by sleep fragmentation, sleep-related respiratory events or periodic leg movements. EDS also tends to persist despite successful treatment of sleep-disordered breathing in DM1 patients. As EDS clearly impacts on physical and social functioning of DM1 patients, studies are needed to identify the best appropriate tools to identify hypersomnia, and clarify the indications for polysomnography (PSG) and multiple sleep latency test (MSLT) in DM1. In addition, further structured trials of assisted nocturnal ventilation and randomized trials of central nervous system (CNS) stimulant drugs in large samples of DM1 patients are required to optimally treat patients affected by this progressive, incurable condition.

Restless legs syndrome--theoretical roles of inflammatory and immune mechanisms

Theories for restless legs syndrome (RLS) pathogenesis include iron deficiency, dopamine dysregulation and peripheral neuropathy. Increased prevalence of small intestinal bacterial overgrowth (SIBO) in controlled studies in RLS and case reports of post-infectious RLS suggest potential roles for inflammation and immunological alterations. A literature search for all conditions associated with RLS was performed. These included secondary RLS disorders and factors that may exacerbate RLS. All of these conditions were reviewed with respect to potential pathogenesis including reports of iron deficiency, neuropathy, SIBO, inflammation and immune changes. A condition was defined as highly-associated if there was a prevalence study that utilized an appropriate control group. Small case reports were recorded but not included as definite RLS-associated conditions. Fifty four diseases, syndromes and conditions have been reported to cause and/or exacerbate RLS. Of these, 38 have been reported to have a higher prevalence than age-matched controls, 9 have adequate sized reports and have general acceptance as RLS-associated conditions and 7 have been reported in case report form. Overall, 42 of the 47 RLS-associated conditions (89%) have also been associated with inflammatory and/or immune changes. In addition, 43% have been associated with peripheral iron deficiency, 40% with peripheral neuropathy and 32% with SIBO. Most of the remaining conditions have yet to be studied for these factors. The fact that 95% of the 38 highly-associated RLS conditions are also associated with inflammatory/immune changes suggests the possibility that RLS may be mediated or affected through these mechanisms. Inflammation can be responsible for iron deficiency and hypothetically could cause central nervous system iron deficiency-induced RLS. Alternatively, an immune reaction to gastrointestinal bacteria or other antigens may hypothetically cause RLS by a direct immunological attack on the central or peripheral nervous system.

Increased prevalence of restless legs syndrome in patients with acromegaly and effects on quality of life assessed by Acro-QoL

Restless legs syndrome (RLS), a neurological sensory-motor disorder characterized by a compelling urge to move the limbs during the night, is a sleep disturbance that impairs quality of life. Prevalence of RLS and consequences on quality of life were investigated in acromegalic patients. Fifty-six patients (20 men, 55.0 ± 1.6 years), 22 with active acromegaly (group 1) and 34 with controlled disease (group 2), and 95 controls (35 men, 52.9 ± 1.1 years) were evaluated by a structured sleep interview concerning insomnia, circadian sleep disorders and excessive diurnal sleepiness (EDS). The Epworth Sleepiness Scale (ESS) questionnaire was administered to those reporting EDS. Patients were investigated by RLS diagnostic interview and International Restless Leg Syndrome-Rating Scale (IRLS-RS). Quality of life was investigated by AcroQoL questionnaire. RLS was diagnosed in 21% of acromegalics and in 4% of controls (P < 0.002). Prevalence of RLS and mean IRLS-RS was higher in group 1 than in group 2 (P < 0.05). Prevalence of insomnia (P < 0.0002) and of EDS (P < 0.05) and mean ESS score (P < 0.01) were higher in RLS-positive than in RLS-free acromegalics. Video-PSG showed that mean sleep latency (P < 0.01), micro-arousal index (P < 0.05) and wakefulness after sleep onset (P < 0.01) were higher, whereas sleep efficiency (P < 0.01) was lower, in RLS-positive than in RLS-free patients. Global and physical AcroQoL scores were significantly lower in RLS-positive than in RLS-free acromegalics (P < 0.01 and P < 0.001, respectively). Prevalence and severity of RLS is increased in patients with active acromegaly and impacts negatively on their physical performances, dramatically impairing quality of life.

Diagnosis of PLMD from increased pulse rate variability on overnight oximetry

STUDY OBJECTIVE

This study was undertaken in a group of patients with periodic limb movement disorder (PLMD) to assess whether the presence of increased pulse rate variability (PRV) without desaturation on overnight oximetry was suggestive of the occurrence of periodic limb movements (PLMs).

METHODS

Seventy sleepy patients with a polysomnographic diagnosis of PLMD and 25 controls with obstructive sleep apnea were included in this retrospective study. All patients had undergone initial domiciliary oximetry and subsequent polysomnography (PSG). The oximetry tracings were independently interpreted by five sleep unit personnel for the presence of increased PRV. Further, the association between increased PRV and PLMs was evaluated in the summary graph of the PSG.

RESULTS

Fifty seven (81.4%) patients had definite evidence of increased PRV without episodes of desaturation on initial oximetry, which was later confirmed to be due to PLMs on PSG. 13 (18.6%) patients had no PRV on oximetry and PSG but had PLMD. The inter-interpreter concurrence in suspecting a diagnosis of PLMD based on oximetry alone was more than 80% in 64 (91%) patients.

CONCLUSION

The presence of isolated increased PRV on overnight oximetry is a valuable tool in suspecting nonsleep apnea disorders like PLMD.