Pathophysiological concepts of restless legs syndrome

Micro- and Nanosized Carriers for Nose-to-Brain Drug Delivery in Neurodegenerative Disorders

Neurodegenerative disorders (NDs) have become a serious health problem worldwide due to the rapid increase in the number of people that are affected and the constantly aging population. Among all NDs, Alzheimer’s and Parkinson’s disease are the most common, and many efforts have been made in the development of effective and reliable therapeutic strategies. The intranasal route of drug administration offers numerous advantages, such as bypassing the blood–brain barrier and providing a direct entrance to the brain through the olfactory and trigeminal neurons. The present review summarizes the available information on recent advances in micro- and nanoscale nose-to-brain drug-delivery systems as a novel strategy for the treatment of Alzheimer’s and Parkinson’s disease. Specifically, polymer- and lipid-base micro- and nanoparticles have been studied as a feasible approach to increase the brain bioavailability of certain drugs. Furthermore, nanocomposites are discussed as a suitable formulation for administration into the nasal cavity.

Genome-wide analysis identified novel susceptible genes of restless legs syndrome in migraineurs

Background

Restless legs syndrome is a highly prevalent comorbidity of migraine; however, its genetic contributions remain unclear.

Objectives

To identify the genetic variants of restless legs syndrome in migraineurs and to investigate their potential pathogenic roles.

Methods

We conducted a two-stage genome-wide association study (GWAS) to identify susceptible genes for restless legs syndrome in 1,647 patients with migraine, including 264 with and 1,383 without restless legs syndrome, and also validated the association of lead variants in normal controls unaffected with restless legs syndrome (n = 1,053). We used morpholino translational knockdown (morphants), CRISPR/dCas9 transcriptional knockdown, transient CRISPR/Cas9 knockout (crispants) and gene rescue in one-cell stage embryos of zebrafish to study the function of the identified genes.

Results

We identified two novel susceptibility loci rs6021854 (in VSTM2L) and rs79823654 (in CCDC141) to be associated with restless legs syndrome in migraineurs, which remained significant when compared to normal controls. Two different morpholinos targeting vstm2l and ccdc141 in zebrafish demonstrated behavioural and cytochemical phenotypes relevant to restless legs syndrome, including hyperkinetic movements of pectoral fins and decreased number in dopaminergic amacrine cells. These phenotypes could be partially reversed with gene rescue, suggesting the specificity of translational knockdown. Transcriptional CRISPR/dCas9 knockdown and transient CRISPR/Cas9 knockout of vstm2l and ccdc141 replicated the findings observed in translationally knocked-down morphants.

Conclusions

Our GWAS and functional analysis suggest VSTM2L and CCDC141 are highly relevant to the pathogenesis of restless legs syndrome in migraineurs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01409-9.

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.

Migraine and sleep disorders: a systematic review

Migraine and sleep disorders are common and often burdensome chronic conditions with a high prevalence in the general population, and with considerable socio-economic impact and costs.The existence of a relationship between migraine and sleep disorders has been recognized from centuries by clinicians and epidemiological studies. Nevertheless, the exact nature of this association, the underlying mechanisms and interactions are complex and not completely understood. Recent biochemical and functional imaging studies identified central nervous system structures and neurotransmitters involved in the pathophysiology of migraine and also important for the regulation of normal sleep architecture, suggesting a possible causative role, in the pathogenesis of both disorders, of a dysregulation in these common nervous system pathways.This systematic review summarizes the existing data on migraine and sleep disorders with the aim to evaluate the existence of a causal relationship and to assess the presence of influencing factors. The identification of specific sleep disorders associated with migraine should induce clinicians to systematically assess their presence in migraine patients and to adopt combined treatment strategies.

Restless in the mouse cage-A new genetic model for restless legs syndrome: An Editorial Highlight for "Deficiency of Meis1, a transcriptional regulator, in mice and worms:Neurochemical and behavioral characterizations with implications in the restless legs syndrome" on page 522

Restless legs syndrome (RLS) is a movement disorder that is characterized by an uncomfortable sensation in the legs, and the urge to move the legs. Meis1 has previously identified as a risk gene for RLS. This Editorial highlights the study by Lyu and colleagues who developed a novel genetic mouse model heterozygous for Meis1 expression in neurons of the central nervous system. Using behavioral tests, the authors established hyperactivity of the mice, reminiscent of symptoms found in RLS patients. In addition, the authors took a closer look at the iron, dopaminergic, and cholinergic system of these mice.

The role of dopamine pharmacotherapy and addiction-like behaviors in Parkinson's disease

Addictions involve a spectrum of behaviors that encompass features of impulsivity and compulsivity, herein referred to as impulsive-compulsive spectrum disorders (ICSDs). The etiology of ICSDs likely involves a complex interplay among neurobiological, psychological and social risk factors. Neurobiological risk factors include the status of the neuroanatomical circuits that govern ICSDs. These circuits can be altered by disease, as well as exogenous influences such as centrally-acting pharmacologics. The 'poster child' for this scenario is Parkinson's disease (PD) medically managed by pharmacological treatments. PD is a progressive neurodegenerative disease that involves a gradual loss of dopaminergic neurons largely within nigrostriatal projections. Replacement therapy includes dopamine receptor agonists that directly activate postsynaptic dopamine receptors (bypassing the requirement for functioning presynaptic terminals). Some clinically useful dopamine agonists, e.g., pramipexole and ropinirole, exhibit high affinity for the D2/D3 receptor subtypes. These agonists provide excellent relief from PD motor symptoms, but some patients exhibit debilitating ICSD. Teasing out the neuropsychiatric contribution of PD-associated pathology from the drugs used to treat PD motor symptoms is challenging. In this review, we posit that modern clinical and preclinical research converge on the conclusion that dopamine replacement therapy can mediate addictions in PD and other neurological disorders. We provide five categories of evidences that align with this position: (i) ICSD prevalence is greater with D2/D3 receptor agonist therapy vs PD alone. (ii) Capacity of dopamine replacement therapy to produce addiction-like behaviors is independent of disease for which the therapy is being provided. (iii) ICSD-like behaviors are recapitulated in laboratory rats with and without PD-like pathology. (iv) Behavioral pathology co-varies with drug exposure. (v) ICSD Features of ICSDs are consistent with agonist pharmacology and neuroanatomical substrates of addictions. Considering the underpinnings of ICSDs in PD should not only help therapeutic decision-making in neurological disorders, but also apprise ICSDs in general.

The role of BTBD9 in the cerebral cortex and the pathogenesis of restless legs syndrome

Restless legs syndrome (RLS) is a nocturnal neurological disorder affecting up to 10% of the population. It is characterized by an urge to move and uncomfortable sensations in the legs which can be relieved by movements. Mutations in BTBD9 may confer a higher risk of RLS. We developed Btbd9 knockout mice as an animal model. Functional alterations in the cerebral cortex, especially the sensorimotor cortex, have been found in RLS patients in several imaging studies. However, the role of cerebral cortex in the pathogenesis of RLS remains unclear. To explore this, we used in vivo manganese-enhanced MRI and found that the Btbd9 knockout mice had significantly increased neural activities in the primary somatosensory cortex (S1) and the rostral piriform cortex. Morphometry study revealed a decreased thickness in a part of S1 representing the hindlimb (S1HL) and M1. The electrophysiological recording showed Btbd9 knockout mice had enhanced short-term plasticity at the corticostriatal terminals to D1 medium spiny neurons (MSNs). Furthermore, we specifically knocked out Btbd9 in the cerebral cortex of mice (Btbd9 cKO). The Btbd9 cKO mice showed a rest-phase specific motor restlessness, decreased thermal sensation, and a thinner S1HL and M1. Both Btbd9 knockout and Btbd9 cKO exhibited motor deficits. Our results indicate that systematic BTBD9 deficiency leads to both functional and morphometrical changes of the cerebral cortex, and an alteration in the corticostriatal pathway to D1 MSNs. Loss of BTBD9 only in the cerebral cortex is sufficient to cause similar phenotypes as observed in the Btbd9 complete knockout mice.

Mobility Deficits Assessed With Mobile Technology: What Can We Learn From Brain Iron-Altered Animal Models?

Background: Recent developments in mobile technology have enabled the investigation of human movements and mobility under natural conditions, i.e., in the home environment. Iron accumulation in the basal ganglia is deleterious in Parkinson's disease (i.e., iron accumulation with lower striatal level of dopamine). The effect of iron chelation (i.e., re-deployment of iron) in Parkinson's disease patients is currently tested in a large investigator-initiated multicenter study. Conversely, restless legs syndrome (RLS) is associated with iron depletion and higher striatal level of dopamine. To determine from animal models which movement and mobility parameters might be associated with iron content modulation and the potential effect of therapeutic chelation inhuman.

Methods: We recapitulated pathophysiological aspects of the association between iron, dopamine, and neuronal dysfunction and deterioration in the basal ganglia, and systematically searched PubMed to identify original articles reporting about quantitatively assessed mobility deficits in animal models of brain iron dyshomeostasis.

Results: We found six original studies using murine and fly models fulfilling the inclusion criteria. Especially postural and trunk stability were altered in animal models with iron overload. Animal models with lowered basal ganglia iron suffered from alterations in physical activity, mobility, and sleep fragmentation.

Conclusion: From preclinical investigations in the animal model, we can deduce that possibly also in humans with iron accumulation in the basal ganglia undergoing therapeutic chelation may primarily show changes in physical activity (such as daily “motor activity”), postural and trunk stability and sleep fragmentation. These changes can readily be monitored with currently available mobile technology.

The association between migraine and restless legs syndrome: an updated systematic review and meta-analysis

OBJECTIVE

This study aims to gain further insight into the association between migraine and restless legs syndrome (RLS).

METHODS

A literature search of PubMed, Embase, and Web of Science was performed for studies investigating the association between any migraine and RLS; a meta-analysis of eligible studies was conducted to determine a pooled effect estimate for the association.

RESULTS

Fifteen studies were included in this meta-analysis. The studies differed in methodology, but all investigated the association between migraine and RLS. Pooled RLS prevalence was 17.0% [95% confidence interval (CI) 15.0%-20.0%] among migraineurs, and 7.0% (95% CI 5.0%-8.0%) among no migraine individuals. Pooled analyses showed that migraine was associated with RLS, but effect estimates were substantially higher in case-control studies [pooled odds ratio (OR) = 3.77, 95% CI 2.73-5.21; I² = 50.1%] than in cross-sectional studies (pooled OR = 1.25, 95% CI 1.11-1.41; I² = 34.2%). Subgroup analyses were not conducted to find potential factors that affect this association because of too few available studies.

CONCLUSIONS

This updated meta-analysis confirms the association between migraine and RLS. Future studies should specifically investigate the potential effects of gender, age, aura status, and type (episodic or chronic) of migraine on the association between the two disorders.

Comparative Efficacy and Safety of Clonazepam versus Nortriptyline in Restless Leg Syndrome among Forty Plus Women: A Prospective, Open-Label Randomized Study

Aims and Objectives:

The aim of this study is to compare the effect of clonazepam and nortriptyline on rate, frequency, and severity of restless leg syndrome (RLS) in above 40 years women suffering from RLS.

Materials and Methods:

A prospective, randomized, open-label comparative study was conducted at a tertiary care teaching hospital for 1 year. Restless legs syndrome (RLS) diagnosis was based on four essential clinical criteria established by the International RLS Study Group in 2003. Patients were randomized into two groups. Group 1 received tablet clonazepam 0.5 mg bedtime orally daily. Group 2 received tablet nortriptyline 25 mg bedtime orally daily. The primary efficacy endpoints by the International Restless leg Syndrome Scale (IRLS) were evaluated at 0, 4, and 8 weeks. Adverse drug events and safety assessment for vital signs such as blood pressure, pulse, heart rate, waist circumference, and body mass index were compared between two groups.

Results:

Effect on mean IRLSS was statistically more in clonazepam group in comparison to nortriptyline group with comparable results at 8 weeks (P < 0.001), but at 4 weeks, nortriptyline showed less improvement (P < 0.01) versus P < 0.001 in nortriptyline group. Thus, nortriptyline reported relatively more improvement on IRLSS numerically in comparison to clonazepam. Nortriptyline proved to be statistically better in improving the frequency of RLS with comparison to clonazepam, whereas the results were comparable with regard to rate and the severity of RLS. Both the groups were relatively safe and did not produce any change in biochemical parameters and were free from any serious or severe adverse events and overall, both the treatments were well tolerated.

Conclusion:

Both the drugs provided clinically and statistical significant effect on RLS when compared with their respective baselines. However, nortriptyline proved to be statistically better in improving the frequency of RLS in comparison to clonazepam, whereas the results were comparable with regard to rate and the severity of RLS on intergroup comparison. Both the drugs were well tolerated.

Clinical and radiological characteristics of restless legs syndrome following acute lacunar infarction

BACKGROUND

Recent studies have suggested that cerebral ischemic infarction may contribute to the development of restless legs syndrome (RLS). This study analyzed the clinical and radiological profiles of RLS with onset after acute lacunar infarction.

METHODS

In this retrospective study we enrolled 244 consecutive patients with acute lacunar infarction between January 2012 and June 2014. RLS was identified and evaluated based on the International RLS Rating Scale (IRLS-RS). Individual sleep quality was assessed using the Epworth Sleepiness Scale (ESS). Psychological state was also assessed using the Hamilton Depression Scale (HDS) and the Hamilton Anxiety Scale (HAS).

RESULTS

The incidence of RLS in patients with lacunar infarction was 5.33%. Our participant group consisted of nine males and four females. Three patients had symptoms in bilateral limbs, and 10 patients had symptoms only contralateral to the cerebral infarction. The infarctions were localized to the pons, centrum semiovale, thalamus, putamen, medulla, and occipital lobe. Contralateral paralysis was found in 13 patients, and contralateral sensory deficit in seven patients. The average IRLS-RS, ESS, HDS, HAS scores were 19.07 ± 8.70, 4.69 ± 5.82, 4.38 ± 4.68, and 3.85 ± 4.76, respectively. Nine patients had diabetes mellitus. After administration of dopaminergic drugs, patients' RLS significantly improved.

CONCLUSIONS

The incidence of RLS after acute lacunar infarction was 5.33%. Pons, centrum semiovale, and basal ganglia were the common locations of responsible lesions. Compared to idiopathic RLS, symptoms of RLS after acute lacunar infarction appeared more unilateral and more likely involved the arm. Moreover, diabetes mellitus may be a risk factor for RLS in stroke patients.

Pharmacological insights into impulsive-compulsive spectrum disorders associated with dopaminergic therapy

Impulsive-compulsive spectrum disorders are associated with dopamine agonist therapy in some patients. These untoward outcomes occur with direct-acting, full and partial agonists at D2 dopamine family receptors. The disorders typically emerge during chronic treatment, and exhibit common features that are independent of the neurological or psychiatric pathology for which the initial therapy was indicated. It is well-documented that the brain is 'plastic', changing in response to alterations to internal factors (e.g., disease processes), as well as external factors (e.g., therapies). The complexities of these clinical scenarios have eluded a clear depiction of the neurobiology for impulsive-compulsive spectrum disorders and engendered considerable debate regarding the mechanistic underpinnings of the disorders. In this opinion, we use pharmacological concepts related to homeostatic compensation subsequent to chronic receptor activation to provide a unifying construct. This construct helps explain the occurrence of impulsive-compulsive spectrum disorders across disease states, and during therapy with full and partial agonists.

Sleep Disorders and Migraine: Review of Literature and Potential Pathophysiology Mechanisms

Migraine shares a complex and poorly understood relationship with sleep. Patients consistently report poor sleep prior to migraine attacks and during them, identifying poor sleep as a migraine trigger. However, anecdotally, sleep is reported to serve a therapeutic role in terminating headache. Are the associations between migraine and sleep simply the result of various bidirectional relationships? A growing body of evidence suggests there may be a common underlying etiology as well. Our objective was to review studies of sleep and migraine from the last 2 decades utilizing validated subjective and objective measures of sleep and to explore potential mechanisms underlying this complex relationship by incorporating recent advances in neuroscience. We specifically focus on insomnia, obstructive sleep apnea, parasomnias, sleep related movement disorders, and REM sleep related disorders and their relationship to migraine. Parts of brainstem-cortical networks involved in sleep physiology are unintentionally being identified as important factors in the common migraine pathway. Recent discoveries on anatomic localization (the hypothalamus as a key and early mediator in the pathophysiology of migraine), common mediating signaling molecules (such as serotonin and dopamine), and the discovery of a new CNS waste removal system, the glymphatic system, all point to a common pathophysiology manifesting in migraine and sleep problems.

Evaluation of Optical Coherence Tomography Results and Cognitive Functions in Patients with Restless Legs Syndrome

Introduction

The aim of this study was to evaluate whether retinal neural network was impaired and cognitive functions were disturbed in restless legs syndrome (RLS) considering the hypothesis that there may be a dysfunction in dopaminergic pathways in RLS like in Parkinson's disease. Therefore, we evaluated retinal neural network with optical coherence tomography (OCT) and presence of cognitive impairment with Montreal Cognitive Assessment (MOCA).

Methods

OCT evaluations were performed for 30 RLS patients and 30 healthy controls. Ganglion cell complex was segmented to retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) automatically by the device, and recorded. Additionally, all the patients and the controls were evaluated using MOCA.

Results

No statistically significant difference was detected between RLS and controls in RNFL, GCL, IPL, and choroidal thicknesses. However, total MOCA score and all of its subscale scores were significantly lower in the RLS patients compared with the controls. No significant correlation was detected between OCT and MOCA parameters.

Conclusion

No degeneration was detected in retinal neurons (RNFL, GCL, and IPL) of RLS patients. However, impairments were seen in MOCA total and subscale scores of these patients. On the other hand, no significant correlation was detected between MOCA scores and RNFL, GCL, or IPL thicknesses. These findings suggest decrease in cognitive functions of RLS patients probably due to dopaminergic dysfunction regardless of anatomical neural degeneration. Longitudinal follow-up studies are warranted to evaluate whether neuronal degeneration will develop.

Altered Brain Functional Connectome in Migraine with and without Restless Legs Syndrome: A Resting-State Functional MRI Study

Background

Migraine is frequently comorbid with restless legs syndrome (RLS), both displaying functional connectivity (FC) alterations in multiple brain networks, although the neurological basis of this association is unknown.

Methods

We performed resting-state functional magnetic resonance imaging and network-wise analysis of FC in migraine patients with and without RLS and healthy controls (CRL). Network-based statistics (NBS) and composite FC matrix analyses were performed to identify the patterns of FC changes. Correlation analyses were performed to identify associations between alterations in FC and clinical profiles.

Results

NBS results revealed that both migraine patients with and without RLS exhibited lower FC than CRL in the dorsal attention, salience, default mode, cingulo-opercular, visual, frontoparietal, auditory, and sensory/somatomotor networks. Further composite FC matrix analyses revealed differences in FC of the salience, default mode to subcortical and frontoparietal, auditory to salience, and memory retrieval networks between migraine patients with and without RLS. There was a trend toward a negative association between RLS severity and cross-network abnormalities in the default mode to subcortical network.

Discussion

Migraine patients with and without RLS exhibit disruptions of brain FC. Such findings suggest that these disorders are associated with differential neuropathological mechanisms and may aid in the future development of neuroimaging-driven biomarkers for these conditions.

Restless Legs Syndrome: From Pathophysiology to Clinical Diagnosis and Management

Restless legs syndrome (RLS), a common neurological sensorimotor disorder in western countries, has gained more and more attention in Asian countries. The prevalence of RLS is higher in older people and females. RLS is most commonly related to iron deficiency, pregnancy and uremia. The RLS symptoms show a significant circadian rhythm and a close relationship to periodic limb movements (PLMs) in clinical observations, while the pathophysiological pathways are still unknown. The diagnostic criteria have been revised in 2012 to improve the validity of RLS diagnosis. Recent studies have suggested an important role of iron decrease of brain in RLS pathophysiology. Dopaminergic (DA) system dysfunction in A11 cell groups has been recognized long ago from clinical treatment and autopsy. Nowadays, it is believed that iron dysfunction can affect DA system from different pathways and opioids have a protective effect on DA system. Several susceptible single nucleotide polymorphisms such as BTBD9 and MEIS1, which are thought to be involved in embryonic neuronal development, have been reported to be associated with RLS. Several pharmacological and non-pharmacological treatment are discussed in this review. First-line treatments of RLS include DA agents and α2δ agonists. Augmentation is very common in long-term treatment of RLS which makes prevention and management of augmentation very important for RLS patients. A combination of different types of medication is effective in preventing and treating augmentation. The knowledge on RLS is still limited, the pathophysiology and better management of RLS remain to be discovered.

Treatment of restless legs syndrome with the selective AMPA receptor antagonist perampanel

OBJECTIVES

Perampanel is a selective, noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA) antagonist that has been approved for the treatment of partial seizures. Here we report on the first open study evaluating its efficacy in idiopathic restless legs syndrome (RLS).

METHODS

The study was designed as a prospective two-month open trial. Twenty-two previously untreated patients diagnosed with idiopathic RLS began treatment with 2 mg perampanel, which was increased to 4 mg at week four if clinically necessary. Multiple Suggested Immobilization Tests (mSITs) followed by polysomnography were performed at baseline and at week eight. Severity ratings were performed every two weeks by means of the IRLS scale, and Clinical Global Index (CGI) subscale. The main endpoint was therapeutic response, defined as a 50% improvement in IRLS total score.

RESULTS

Twenty patients completed the study. During the 8-week treatment period, the IRLS score improved from a mean (±standard deviation (SD)) 23.7 ± 4.2 to 11.5 ± 5.3. Twelve of 20 patients were full responders (improvement 50% in IRLS total score), and four responded partially. The mean effective dose of perampanel at the end of treatment was 3.8 mg/day. Treatment with perampanel also resulted in an improvement in the mean (±SD) periodic leg movement index from 27.8 ± 6.9 to 4.36 ± 2.0. Perampanel was well tolerated. The main side effects were dizziness, somnolence, headache, and irritability.

CONCLUSION

These preliminary results suggest that perampanel has significant therapeutic effects on both sensory and motor symptoms. If confirmed by future controlled studies, perampanel might become a promising alternative to existing dopaminergic treatments due to its glutamatergic mechanism of action. The study provides class IV evidence supporting the therapeutic effects of perampanel in RLS/WED.

Evaluation of neurodegeneration through visual evoked potentials in restless legs syndrome

Restless legs syndrome (RLS) is a disease characterized by some type of dysesthesia, an indescribable abnormal sensation in the extremities. Our objective was to determine whether the visual evoked potentials (VEP) can be used as a quantitative monitoring method to evaluate demyelination-remyelination and neurodegeneration in the patients with RLS. The present study was carried out prospectively. It was planned to determine normal or pathological conditions in the form of increased latency or decreased amplitude of VEP and to evaluate possible pathologies in the visual and retinal pathways at early stages and at months 3 and 6 of follow-up in the patients with RLS (with or without iron deficiency anemia), in those without RLS (at the time of diagnosis prior to any medical therapy) without any visual symptoms. It was observed that latency of VEP improved but didn't return to normal limits following treatment with dopamin agonists, iron, or combination of both and that there was no significant difference between the post-treatment data and those of the control group. These results in combination with the fact that the latencies and amplitudes didn't return to normal levels despite the 6-month-treatment but showed a progressive course with partial regeneration suggests that there was incomplete remyelination. It should be kept in mind that this syndrome is likely to be a part of neurodegenerative process.

Prevalence of restless legs syndrome in migraine patients with and without aura: a cross-sectional, case-controlled study

BACKGROUND

Although the comorbidity of migraine and restless legs syndrome (RLS) has been well-documented, the association between RLS and migraine frequency has yet to be elucidated. The present study aims to evaluate the prevalence of RLS among individuals who experience low-frequency, high-frequency, or chronic migraine presenting with and without aura.

METHODS

We conducted a cross-sectional, case-controlled study involving 505 participants receiving outpatient headache treatment. Standardized questionnaires were administered to collect information on experiences of migraine, RLS, sleep quality, anxiety, depression, and demographics. Participants were categorized into low-frequency (1-8/month), high-frequency (9-14/month), and chronic (≥15/month) headache groups. RLS was diagnosed according to the criteria outlined by the International RLS Study Group (IRLSSG). The Pittsburgh Sleep Quality Index (PSQI) and Hospital Anxiety and Depression Scale (HADS) were used to assess sleep quality and identify symptoms of anxiety and depression. Associations between migraine frequency and RLS prevalence were investigated using multivariate linear and logistic regression.

RESULTS

Univariate analysis revealed an effect of migraine frequency on RLS prevalence (p = 0.026), though this effect did not persist following adjustment for baseline characteristics (p = 0.256). The trend was robust in patients whose migraines presented with auras (p _univariate = 0.002; p _multivariate = 0.043) but not in those without auras (p _univariate and p _multivariate > 0.05). Higher anxiety [odds ratio (OR) = 1.18, p = 0.019] and sleep disturbance (OR = 1.17, p = 0.023) scores were associated with higher RLS prevalence.

CONCLUSIONS

Higher migraine frequency correlates with a higher prevalence of RLS, particularly among patients with auras.

Susceptible genes of restless legs syndrome in migraine

Objective Several genetic variants have been found to increase the risk of restless legs syndrome (RLS). The aim of the present study was to determine if these genetic variants were also associated with the comorbidity of RLS and migraine in patients. Methods Thirteen single-nucleotide polymorphisms (SNPs) at six RLS risk loci ( MEIS1, BTBD9, MAP2K5, PTPRD, TOX3, and an intergenic region on chromosome 2p14) were genotyped in 211 migraine patients with RLS and 781 migraine patients without RLS. Association analyses were performed for the overall cohort, as well as for the subgroups of patients who experienced migraines with and without aura and episodic migraines (EMs) vs. chronic migraines (CMs). In order to verify which genetic markers were potentially related to the incidence of RLS in migraine patients, multivariate regression analyses were also performed. Results Among the six tested loci, only MEIS1 was significantly associated with RLS. The most significant SNP of MEIS1, rs2300478, increased the risk of RLS by 1.42-fold in the overall cohort ( p = 0.0047). In the subgroup analyses, MEIS1 augmented the risk of RLS only in the patients who experienced EMs (odds ratio (OR) = 1.99, p = 0.0004) and not those experiencing CMs. Multivariate regression analyses further showed that rs2300478 in MEIS1 (OR = 1.39, p = 0.018), a CM diagnosis (OR = 1.52, p = 0.022), and depression (OR = 1.86, p = 0.005) were independent predictors of RLS in migraine. Conclusions MEIS1 variants were associated with an increased risk of RLS in migraine patients. It is possible that an imbalance in iron homeostasis and the dopaminergic system may represent a link between RLS incidence and migraines.

Improvement of restless legs syndrome by nabat: a case series and new hypotheses for research

BACKGROUND

Although many hypotheses have been suggested, the pathophysiology of restless legs syndrome (RLS) has not been fully understood. In this case series, we describe eleven cases with RLS whose symptoms subsided by the use of crystallized sucrose. This kind of sugar, known as nabat, is used in traditional Iranian medicine.

METHODS

Case series.

RESULTS

All patients felt relief 30-60 min after taking 100 grams of dissolved nabat.

CONCLUSIONS

Sucrose seems to carry a special benefit for patients with RLS, and it provides evidence for growing literature demonstrating the different underlying mechanisms of RLS. Possible causes for this concurrence are also discussed.

Increased Risk of Restless Legs Syndrome in Patients With Migraine: A Nationwide Population-Based Cohort Study

Previous studies suggest that an association between restless legs syndrome (RLS) and migraine exists. However, population-based data are unavailable in Asian cohorts. Our study thus aims to evaluate the association between migraine and RLS in a nationwide, population-based cohort in Taiwan and to examine the effects of age, sex, migraine subtype, and comorbidities on RLS development.Data from the Taiwan National Health Insurance Research Database were used. Patients aged 20 years or older with newly diagnosed migraine from 2000 to 2008 were included; 23,641 patients with newly diagnosed migraine and 94,564 subjects without migraine were randomly selected and followed until RLS development, withdrawal from the National Health Insurance, or until the end of 2011. A multivariate Cox proportional hazards regression model was used to explore the risk of RLS in patients with migraine after adjustment for demographic characteristics and comorbidities.Both cohorts were followed for a mean of 7.38 years. After adjustment for covariates, the risk of RLS was 1.42-fold higher (95% confidence interval = 1.13-1.79) in the migraine cohort than in the nonmigraine cohort (7.19 versus 3.42 years per 10,000 person-years). The increased risk was more prominent in males in the migraine cohort (1.87-fold increased risk, 95% confidence interval 1.22-2.85). Neither comorbidity status nor migraine subtype influenced the RLS risk.This population-based study demonstrated that migraine is associated with an increased risk of RLS compared with those without migraine, particularly in male patients with migraine and regardless of the comorbidity status.

Risk of Restless Legs Syndrome Following Tension-Type Headache: A Nationwide Population-Based Cohort Study

Migraine and restless legs syndrome (RLS) appear to be associated, but the relationship between tension-type headache (TTH) and RLS is unknown. This nationwide, population-based, retrospective cohort study explored the potential association between TTH and RLS.We identified 15,504 patients with newly diagnosed TTH from 2000 to 2007 and 62,016 individuals without TTH who were selected by frequency matched based on sex, age, and the index year. The study participants were followed until diagnosed with RLS, withdrawal from the NHI program, or the end of 2011. Cox proportional hazard models were used to identify risk factors for RLS in TTH patients.After adjusting for sex, age, comorbidity, and medications, TTH was significantly associated with an increased risk of RLS (hazard ratio [HR] = 1.57, 95% confidence interval [CI] = 1.22-2.02). The risk was most prominent in patients aged 20 to 39 years in the TTH group, which exhibited a 2.60-fold higher risk (95% confidence interval = 1.53-4.42) of RLS compared with the non-TTH group. The TTH group had a higher risk of RLS than that of the non-TTH group regardless of sex.Tension-type headache appears to be associated with an increased risk of developing RLS. This similarity to migraines may indicate that headache and RLS have a coincident pathophysiological mechanism, a possibility requiring further study. Clinicians should be more attentive to RLS as a possible comorbidity in patients with TTH.

DTI and VBM reveal white matter changes without associated gray matter changes in patients with idiopathic restless legs syndrome

BACKGROUND AND PURPOSE

We evaluated cerebral white and gray matter changes in patients with iRLS in order to shed light on the pathophysiology of this disease.

METHODS

Twelve patients with iRLS were compared to 12 age- and sex-matched controls using whole-head diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) techniques. Evaluation of the DTI scans included the voxelwise analysis of the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD).

RESULTS

Diffusion tensor imaging revealed areas of altered FA in subcortical white matter bilaterally, mainly in temporal regions as well as in the right internal capsule, the pons, and the right cerebellum. These changes overlapped with changes in RD. Voxel-based morphometry did not reveal any gray matter alterations.

CONCLUSIONS

We showed altered diffusion properties in several white matter regions in patients with iRLS. White matter changes could mainly be attributed to changes in RD, a parameter thought to reflect altered myelination. Areas with altered white matter microstructure included areas in the internal capsule which include the corticospinal tract to the lower limbs, thereby supporting studies that suggest changes in sensorimotor pathways associated with RLS.

Sleep and Headache

The interaction between sleep and headache or migraine is powerful and an elevated comorbidity between these 2 disorders has been reported in either adults or children. This comobidity is linked to common neurophysiological and neuroanatomical substrates that are genetically based strongly. The first reports on this relationship were related to the prevalence of parasomnias and sleep-disordered breathing in headache but recent research has expanded the comorbidity to several other sleep disorders, such as restless legs syndrome, periodic limb movements during sleep, and narcolepsy. The assessment of children with headache should always include an accurate anamnesis for the presence of sleep problems either in the child or in the relatives; no correct approach for treating children and adolescents is possible without an integrated method of evaluation and management.

What patients do to counteract the symptoms of Willis-Ekbom disease (RLS/WED): Effect of gender and severity of illness

Objectives:

This study was carried out to assess different counteracting strategies used by patients with idiopathic Willis-Ekbom disease (RLS/WED). Whether these strategies were influenced by gender or disease severity was also assessed.

Materials and Methods:

A total of 173 patients of idiopathic RLS/WED were included in this study. Their demographic data was recorded. Details regarding the RLS/WED and strategies that they used to counteract the symptoms were asked. The severity of RLS/WED was measured with the help of the Hindi version of international restless legs syndrome severity rating scale. They were asked to provide the details regarding the relief obtained from all the strategies they used on three-point scale: no relief, some relief, and complete relief.

Results:

Of the patients, 72% were females. Mean age of the subjects in this study was 39.6 ± 12.6 years, and male subjects were older than females. Four common strategies were reported by the patients to counter the sensations of RLS/WED: moving legs while in bed (85.5%), asking somebody to massage their legs or massaging legs themselves (76.9%), walking (53.2%), and tying a cloth/rope tightly on the legs (39.3%). Of all the patients who moved their legs, 6.7% did not experience any relief, 64.2% reported some relief, and 28.4% reported complete relief. Similarly, of all the patients who used “walking” to counteract symptoms, 50% reported complete relief, 44.5% reported some relief, and the rest did not experience any relief. Many of these patients reported that massage and tying a cloth/rope on legs brought greater relief than any of these strategies. Tying cloth on the leg was more common among females as compared to males (45.9% females vs. 23.5% males; χ² = 7.54; P = 0.006), while patients with moderately severe to severe RLS/WED reported “moving legs in bed” (79.3% in mild to moderate RLS/WED; 91.8% in severe to very severe RLS; χ² = 5.36; P = 0.02).

Conclusion:

Patients with RLS/WED use a variety of strategies to counteract symptoms. These strategies may be influenced by gender, disease severity, and cultural practices.

Structural brain lesions and restless legs syndrome: a cross-sectional population-based study

OBJECTIVE

To evaluate the association between white matter lesion (WML) volume, silent infarcts and restless legs syndrome (RLS) in a population-based study of elderly individuals.

DESIGN

Cross-sectional study.

SETTING

Population-based Three-City study.

PARTICIPANTS

1035 individuals from the Dijon, France, centre of the Three-City study who had available information on volume of WMLs from MRIs and who answered questions about the prevalence of RLS.

PRIMARY OUTCOME MEASURE

Prevalence of RLS.

RESULTS

WML volume was measured using an automated tissue segmentation method. Logistic regression was used to evaluate adjusted associations between tertiles of WML volume and RLS and between silent infarcts and RLS. 218 individuals (21.1%) were determined to have RLS. Compared with those in the first tertile of WML volume, individuals in the second tertile (OR=1.09; 95% CI 0.75 to 1.60) or third tertile (OR=1.17; 95% CI 0.79 to 1.74) did not have an increased prevalence of RLS. We also did not observe associations between the volume of deep or periventricular WML and RLS; nor did we observe an association between silent brain infarcts and RLS (OR=0.74; 95% CI 0.40 to 1.39). These findings were not modified by age or gender.

CONCLUSIONS

Higher volume of WML and the presence of silent infarcts were not associated with an increased prevalence of RLS in this population-based cohort of elderly individuals.

Migraine and restless legs syndrome: a systematic review

BACKGROUND

Restless legs syndrome (RLS) is increasingly being reported as a comorbidity of migraine.

METHODS

We conducted a systematic review and meta-analysis of studies investigating RLS in headache/migraine and vice versa. We calculated the prevalence and 95% confidence intervals (CI) of RLS in headache/migraine, of headache/migraine in RLS and controls, and odds ratios (ORs) of the association between the conditions. We then determined pooled effect estimates for the associations.

RESULTS

We identified 24 studies. RLS prevalence in migraine ranged from 8.7% to 39.0% with no apparent differences based on gender and aura status. Prevalence among controls was compatible with the literature. Migraine prevalence in RLS ranged from 15.1% to 62.6%. We did not pool prevalence data because of high unexplained heterogeneity. High heterogeneity with respect to the association between any migraine and RLS could be explained by study design. Pooled analyses showed substantially higher effect estimates in case-control studies (pooled OR = 4.19, 95% CI 3.07-5.71; I (2) = 0.0%) than in cohort studies (pooled OR = 1.22, 95% CI 1.14-1.30; I (2) = 0.0%).

CONCLUSION

Our results support the concept of RLS as an important comorbidity of migraine. However, the degree of association appears to be strongly determined by study design. Potential effects by gender and aura status and the role of RLS in other headache disorders remain unclear.

Association between restless legs syndrome and migraine: a population-based study

BACKGROUND AND PURPOSE

A higher prevalence of restless legs syndrome (RLS) in migraineurs has been reported in clinical samples and in two large-scale clinical trials performed on healthcare workers but general population-based studies on this topic are lacking. The aim of this study was to assess the association between migraine and RLS in an Italian rural adult population-based setting.

METHODS

The presence of migraine and RLS was assessed via a computer-assisted personal interview and self-administered questionnaires according to current diagnostic criteria in 1567 participants of a preliminary phase of an adult population-based study performed in South Tyrol, Italy.

RESULTS

Migraineurs had an increased risk of having RLS also after adjustment for confounding factors such as age, sex, major depression, anxiety and sleep quality (odds ratio 1.79; confidence interval 1.00-3.19; P = 0.049). This association was not modified by aura status and possible causes of secondary RLS. RLS was not significantly associated with tension-type headache.

CONCLUSIONS

Restless legs syndrome and migraine were associated in our rural adult population. This association could be explained by a possible shared pathogenic pathway which would implicate new management strategies of these two disorders.

Sensory aspects of movement disorders

Movement disorders, which include disorders such as Parkinson's disease, dystonia, Tourette's syndrome, restless legs syndrome, and akathisia, have traditionally been considered to be disorders of impaired motor control resulting predominantly from dysfunction of the basal ganglia. This notion has been revised largely because of increasing recognition of associated behavioural, psychiatric, autonomic, and other non-motor symptoms. The sensory aspects of movement disorders include intrinsic sensory abnormalities and the effects of external sensory input on the underlying motor abnormality. The basal ganglia, cerebellum, thalamus, and their connections, coupled with altered sensory input, seem to play a key part in abnormal sensorimotor integration. However, more investigation into the phenomenology and physiological basis of sensory abnormalities, and about the role of the basal ganglia, cerebellum, and related structures in somatosensory processing, and its effect on motor control, is needed.

Major sleep disorders among women: (women's health series)

Disruption of sleep causes adverse health outcomes and poor quality of life. People with sleep disruption have higher levels than people without disrupted sleep of depression and anxiety and increased rates of cardiovascular diseases. Women have a higher incidence than men of insomnia and depression related to poor sleep. The types of complaints differ significantly between the sexes. Women are more likely than men to complain of insomnia, headache, irritability, and fatigue than the "typical" symptoms of loud snoring and breathing cessation during sleep. Hormones play an important role in sleep in women. Reproductive hormones were found to have a protective effect on sleep apnea in women of premenopausal age. Pregnancy is another period when the prevalence of sleep apnea and restless leg syndrome increases from hormonal effect. Cardiovascular mortality is high in women with obstructive sleep apnea. Continuous positive airway pressure therapy improves outcomes in most cases of obstructive sleep apnea. The epidemiology, risk factors, diagnostic criteria, and therapies for the three most common sleep disorders (insomnia, obstructive sleep apnea, and restless leg syndrome), along with effects of menopause, pregnancy, and social factors on sleep in women, are key considerations for clinicians caring for female patients across the adult life span.

Electro-acupuncture stimulation improves spontaneous locomotor hyperactivity in MPTP intoxicated mice

Bradykinesia is one of the major clinical symptoms of Parkinson`s disease (PD) for which treatment is sought. In most mouse models of PD, decreased locomotor activity can be reflected in an open field behavioral test. Therefore the open field test provides a useful tool to study the clinic symptoms of PD patients. Our previous work demonstrated that 100 Hz electro-acupuncture (EA) stimulation at ZUSANLI and SANYINJIAO protected the dopaminergic nigrostriatal system of C57BL/6 mice from MPTP toxicity, indicating that acupuncture might be an effective therapy for PD sufferers. In the present study, we investigated the effects of 100 Hz EA stimulation on the spontaneous locomotor activity in MPTP injured mice. Here we found that, in MPTP treated mice, the total movements significantly decreased and the movement time, velocity and distance dramatically increased, although the dopaminergic nigrostriatal system was devastated, revealed by immunohistochemistry and HPLC-ECD. After 12 sessions of 100 Hz EA stimulation, the total movements elevated and the movement time, velocity and distance decreased, in MPTP mice. 100 Hz EA increased striatal dopamine content in MPTP mice by 35.9%, but decreased its striatal dopamine turnover. We assumed that the injury of other regions in the brain, such as the A11 group in diencephalon, might be involved in the hypermotility in MPTP mice. The effects of 100 Hz EA on spontaneous locomotor activity in MPTP mice might not relate with the striatal dopamine, but with its neuroprotective and regulatory effects on motor circuits in the brain. Our study suggests that EA might be a promising treatment for neurological disorders including PD.

Prospective study of restless legs syndrome and risk of erectile dysfunction

In our previous cross-sectional study, we found that restless legs syndrome (RLS) was associated with erectile dysfunction (ED). Thus, we conducted a prospective study to examine whether RLS was associated with a higher risk of developing ED based on 6 years of follow-up among 10,394 men (mean age = 63.4 years) in the Health Professionals Follow-up Study. RLS was assessed in 2002 using a set of standardized questions recommended by the International RLS Study Group. Erectile function was assessed by means of questionnaires in 2000, 2004, and 2008. We identified 1,633 incident ED cases. Men with RLS were more likely to develop ED (relative risk = 1.38, 95% confidence interval: 1.14, 1.68; P = 0.001) than were those without the syndrome, after adjustment for potential confounders, such as age, body mass index, smoking, physical activity, other sleep disorders, and snoring status. A higher frequency of RLS symptoms was also associated with an increased risk of ED (P(trend) = 0.001). In conclusion, men with RLS had a higher risk of ED, and the magnitude of the risk increased with a higher frequency of RLS symptoms. Combinations of other sleep disorders with RLS further increased the risk of ED.

Vascular risk factors, cardiovascular disease, and restless legs syndrome in women

BACKGROUND

Previous studies evaluating the association of cardiovascular disease and vascular risk factors with restless legs syndrome showed inconsistent results, especially for the potential relation between various vascular risk factors and restless legs syndrome. We therefore aimed to analyze the relationships between vascular risk factors, prevalent cardiovascular disease, and restless legs syndrome.

METHODS

This is a cross-sectional study of 30,262 female health professionals participating in the Women's Health Study (WHS). Restless legs syndrome was defined according to diagnostic criteria of the International Restless Legs Study Group. Information on vascular risk factors (diabetes, hypertension, hypercholesterolemia, body mass index [BMI], alcohol, smoking, exercise, and family history of myocardial infarction) was self-reported. Cardiovascular disease events (coronary revascularization, myocardial infarction, and stroke) were confirmed by medical record review. Prevalent major cardiovascular disease was defined as nonfatal stroke or nonfatal myocardial infarction. Logistic regression models were used to evaluate the association between vascular risk factors, prevalent cardiovascular disease, and restless legs syndrome.

RESULTS

Of the 30,262 participants (mean age: 63.6 years), 3624 (12.0%) reported restless legs syndrome. In multivariable-adjusted models, BMI (odds ratio [OR] for BMI ≥35 kg/m(2), 1.35; 95% confidence interval [CI], 1.17-1.56), diabetes (OR, 1.19; 95% CI, 1.04-1.35), hypercholesterolemia (OR, 1.17; 95% CI, 1.09-1.26), smoking status (OR for ≥15 cigarettes/day, 1.41; 95% CI, 1.19-1.66), and exercise (OR for exercise ≥4 times/week, 0.84; 95% CI, 0.74-0.95) were associated with restless legs syndrome prevalence. We found no association between prevalent cardiovascular disease (major cardiovascular disease, myocardial infarction, and stroke) and restless legs syndrome prevalence. Women who underwent coronary revascularization had a multivariable-adjusted OR of 1.39 (1.10-1.77) for restless legs syndrome.

CONCLUSIONS

In this large cohort of female health professionals, various vascular risk factors are associated with the prevalence of restless legs syndrome. We could not confirm the results of previous reports indicating an association between prevalent cardiovascular disease and restless legs syndrome.

The conserved dopaminergic diencephalospinal tract mediates vertebrate locomotor development in zebrafish larvae

The most conserved part of the vertebrate dopaminergic system is the orthopedia (otp)-expressing diencephalic neuronal population that constitutes the dopaminergic diencephalospinal tract (DDT). Although studies in the neonatal murine spinal cord in vitro suggest an early locomotor role of the DDT, the function of the DDT in developing vertebrates in vivo remains unknown. Here, we investigated the role of the DDT in the locomotor development of zebrafish larvae. To assess the development of the behavioral and neural locomotor pattern, we used high-throughput video tracking in combination with peripheral nerve recordings. We found a behavioral and neural correspondence in the developmental switch from an immature to mature locomotor pattern. Blocking endogenous dopamine receptor 4 (D(4)R) signaling in vivo either before or after the developmental switch prevented or reversed the switch, respectively. Spinal transections of post-switch larvae reestablished the immature locomotor pattern, which was rescued to a mature-like pattern via spinal D(4)R agonism. Selective chemogenetic ablation of otp b (otpb) neurons that contribute to the DDT perpetuated the immature locomotor pattern in vivo. This phenotype was recapitulated by diencephalic transections that removed the dopaminergic otpb population and was rescued to a mature-like locomotor pattern by D(4)R agonism. We conclude that the dopaminergic otpb population, via the DDT, is responsible for spinal D(4)R signaling to mediate the developmental switch to the mature locomotor pattern of zebrafish. These results, integrated with the mammalian literature, suggest that the DDT represents an evolutionarily conserved neuromodulatory system that is necessary for normal vertebrate locomotor development.

Increased frequency of restless legs syndrome in atopic dermatitis

BACKGROUND

Restless legs syndrome (RLS) is characterized by an unpleasant sensation in the legs, which is difficult to describe, but produces an urge to move the legs frequently.

AIM

To assess the prevalence and severity of RLS in patients with atopic dermatitis (AD) and patients with psoriasis, and to investigate the factors potentially associated with RLS.

METHODS

In total, 253 people were enrolled (120 with AD, 50 with psoriasis and 83 healthy controls). A diagnosis of RLS was made according to the criteria of the International RLS Study Group (IRLSSG), and severity was assessed using the IRLSSG severity scale.

RESULTS

RLS was significantly more common in patients with AD (40.8%) than in patients with psoriasis (18.0%) or in controls (10.8%) (P<0.01 and P<0.001, respectively). Prevalence of RLS was higher in patients with active AD than in those with inactive AD (55.3% vs. 23.6%) or controls. There was a significant difference in RLS prevalence between patients with active and those with iactive AD, between patients with active AD and healthy controls, between patients with active AD and patients with psoriasis, and between patients with inactive AD and healthy controls (P<0.001, P<0.001, P<0.001, P=0.04, respectively). There was no significant difference in RLS prevalence between patients with active AD and patients with psoriasis, or between patients with psoriasis and healthy controls (P>0.05). Of patients who were positive for RLS, 56.9% had a family history of atopy and 40.3% had a family history of RLS, and there was a significant relationship between the presence of RLS and family history of atopy or RLS (P<0.001 for both).

CONCLUSIONS

RLS is common in patients with AD, particularly in those with active disease.

Growing pains: twin family study evidence for genetic susceptibility and a genetic relationship with restless legs syndrome

BACKGROUND

Growing pains (GP) is a prevalent familial childhood disorder of unknown aetiology. Familial occurrence of GP, and individual and familial association of GP with restless legs syndrome (RLS) has been reported.

METHODS

We applied a twin family design to search for evidence of genetic susceptibility to GP, and for a genetic relationship between GP and RLS. The parents of 1843 twin pairs aged 3-16 years were administered a questionnaire, which identified 88 pairs with at least one twin individual fulfilling criteria for GP. Standard questionnaires for history of GP and RLS were completed for these twin pairs, their siblings and parents.

RESULTS

Twenty-five of 34 monozygotic (MZ) pairs were concordant for GP, compared with 12 of the 54 dizygotic (DZ) pairs. The casewise concordance was 0.85 and 0.36 for MZ and DZ pairs, respectively (p < 0.001). The lifetime GP prevalence for relatives of twins with GP was 51% for non-twin siblings, 47% for parents. Twenty-three percent of twin individuals with GP met RLS criteria compared with 8% of twin individuals without GP (p = 0.03). Of the twins with GP concordance, 19% met RLS criteria compared with 2% of twins with GP discordance (p = 0.01). In two MZ pairs, one had GP and the other RLS. The lifetime prevalence of RLS was 40% for mothers, and 24% for fathers and 18% for non-twin siblings.

CONCLUSION

This first twin family study of GP provides evidence for a genetic aetiology and for a genetic relationship to RLS.

Migraine and restless legs syndrome in women

BACKGROUND

Few clinic-based studies report an association between migraine and restless legs syndrome (RLS); however, population-based data are unavailable.

METHODS

Cohort study among 31,370 women participating in the Women's Health Study. We had detailed self-reported information on migraine, including aura status, and RLS. RLS was ascertained at the 9-year follow-up. We calculated odds ratios (OR) and 95% confidence intervals (CI) for the association between migraine and RLS. We investigated any indication of migraine until RLS ascertainment as well as migraine with and without aura at baseline, prior migraine before baseline, and new reports of migraine during follow-up.

RESULTS

At baseline or during follow-up 6857 (21.9%) women reported any migraine. These women had an increased risk for RLS (multivariable-adjusted OR = 1.22; 95%CI 1.13-1.32). Further analyses indicated a similar association for migraine with aura (multivariable-adjusted OR = 1.27; 95%CI 1.10-1.48) and migraine without aura (multivariable-adjusted OR = 1.24; 95%CI 1.09-1.40) as well as for new reports of migraine during follow-up (multivariable-adjusted OR = 1.30; 95%CI 1.10-1.54). Prior migraine did not appear to be associated with RLS.

CONCLUSIONS

Our data suggest an association between migraine and RLS at the population level. The association is similar for migraine with and without aura and for new reports of migraine during follow-up.

Small fiber function in drug naïve patients with idiopathic restless legs syndrome

To assess whether idiopathic restless legs syndrome (RLS) is associated with small fiber abnormalities, we evaluated somatic and autonomic small fiber function in 56 patients with idiopathic RLS and 36 age-matched and sex-matched healthy controls using quantitative sensory testing and quantitative sudomotor axon reflex tests. The warm detection thresholds (WDT) of the hands (p=0.017) and feet (p=0.008) were higher in patients with RLS than in controls. Cooling detection thresholds (CDT) were higher in the feet of patients with RLS than controls (p<0.001), but CDT in the hands did not differ between groups (p=0.161). There were no significant between-group differences in total sweat volume and sweat production in the forearms, proximal legs, distal legs, and feet (p>0.1 each). These findings suggest that abnormal sensory perception in patients with idiopathic RLS may result from impairment of central somatosensory processing rather than small fiber neuropathy.

A comparison of gray matter density in restless legs syndrome patients and matched controls using voxel-based morphometry

BACKGROUND

Restless legs syndrome (RLS) is a common neurological disorder the pathophysiology of which is incompletely understood. Four studies have examined structural differences between the brains of RLS patients and healthy controls, using voxel-based morphometry (VBM). All 4 studies have provided different results.

METHODS

Optimized VBM was used to search for structural differences in gray matter density. Sixteen RLS patients naïve to dopaminergic drugs and 16 age- and sex-matched controls received structural T1-weighted MR scans. Structural data were analyzed using FSL-VBM.

RESULTS

No difference in gray matter density was detected between the two groups (voxel-wise significance: no significant voxels at P= .89 (whole brain Family Wise Error (FWE) corrected); no significant voxels at P < .05 (whole brain False Discovery Rate (FDR) corrected; smallest achievable FDR threshold .99).

CONCLUSION/DISCUSSION

The present study did not replicate (confirm) previous findings of structural brain changes in RLS, but instead supported the findings of a recent study showing a lack of gray matter alteration in an elderly RLS population. More specifically, the results do not support neuronal loss as an underlying disease mechanism in RLS. Potential limitations in the application of VBM are also discussed.

Restless legs syndrome and risk of incident cardiovascular disease in women and men: prospective cohort study

OBJECTIVES

To evaluate the association between restless legs syndrome (RLS) and incident cardiovascular disease (CVD).

DESIGN

Prospective cohort study.

SETTING

Women's Health Study (WHS) and Physicians' Health Study (PHS), USA.

PARTICIPANTS

29 756 female health professionals aged ≥45 years and 19 182 male physicians aged ≥40 years at baseline.

MAIN OUTCOME MEASURES

Main outcome was incidence of major CVD; secondary outcomes were first incidence of myocardial infarction, stroke, death due to CVD or coronary revascularisation.

RESULTS

3487 (11.7%) women and 1373 (7.2%) men met International Restless Legs Study Group criteria for RLS. In the WHS 450 major CVD events occurred and 1064 major CVD events were confirmed in the PHS. In both cohorts, RLS was not associated with increased risk of major CVD, stroke, myocardial infarction, CVD death or coronary revascularisation. After adjustment for major vascular risk factors, the HRs (95% CI) for major CVD were 1.15 (0.88 to 1.50) in women and 1.01 (0.81 to 1.25) in men. Highest multivariable-adjusted HRs were 1.29 (0.91 to 1.82) for total stroke in women and 1.22 (0.87 to 1.70) for CVD death in men. Excluding participants with comorbidities potentially leading to RLS did not substantially change the effect estimates.

CONCLUSIONS

In these large prospective studies of female and male health professionals, RLS was not associated with an increased risk of any incident CVD event. The data do not support the hypothesis that RLS is a marker of increased risk of vascular disease.

Evaluation of periodic limb movements in a putative animal model of restless leg syndrome

Restless leg syndrome (RLS) is a major healthcare burden with increasing prevalence. It has been demonstrated that periodic limb movements (PLM) can occur as an isolated phenomenon, but they are often associated with this syndrome and are the only symptom of this disorder that can be measured electrophysiologically. The aim of this study was to examine the sleep-wake behavior and the presence of limb movement in a rat model of RLS induced by lesioning the A11 dopaminergic nuclei with the neurotoxin 6-hydroxydopamine (6-OHDA). Rats were implanted with electrodes for electrocorticography and electromyography. Sleep recordings were monitored during light/dark periods lasting 12 hours each and were evaluated on days 7, 15, and 28 after injection of the drug or phosphate-buffered saline (PBS). A control group that did not receive any injection was also included. Wakefulness percentages were generated for 4-hour segments of the dark period, yielding the following 3 bins: 7 PM to 11 PM, 11 PM to 3 AM, and 3 PM to 7 PM. Additionally, slow wave sleep, paradoxical sleep, wakefulness, and limb movements were evaluated over the entire 12 hours of the light/dark cycle. All A11-lesioned rats exhibited an increased percentage of wakefulness during the last block of the dark period, as would be expected for an animal model of this syndrome. In addition, at all time points after lesioning, these animals presented increased frequencies of limb movement during both the light and the dark periods. These alterations were reversed by the acute administration of the dopaminergic agonist pramipexole. This animal model strengthens the notion that 6-OHDA-induced A11 lesions can be a valid animal model for RLS and PLM.

[Frequently occurring sleep disorders]

Some sleep disorders are frequently found in the general population. The most common include restless legs syndrome, insomnia, and sleep apnea. These sleep disorders are well classified and can easily be diagnosed and treated. Since they are risk factors for cardiovascular and psychiatric disorders, early diagnosis and treatment are essential to prevent these sequelae. The impairments caused by these sleep disorders (e.g., due to daytime sleepiness, sleep disruption, or cognitive deficits) can result in a significant reduction in a person's quality of life. The diagnostic and therapeutic recommendations were taken from the S3 guideline "Nonrestorative sleep/sleep disorders" by the German Sleep Society. The levels of evidence were given according to the recommendations of the Oxford Centre for Evidence-based Medicine.

Alterations in pain responses in treated and untreated patients with restless legs syndrome: associations with sleep disruption

OBJECTIVE

There has been recent interest in characterizing potential abnormalities of pain processing in patients with sleep disorders such as Restless Legs Syndrome (RLS). The aim of this study was to evaluate psychophysical responses to noxious heat and pressure stimuli in both treated and untreated RLS patients, compared to matched controls.

METHODS

This study is a cross-sectional group comparison of RLS patients with matched controls. A total of 31 patients (15 treated, 16 untreated) with a confirmed diagnosis of RLS were compared to 18 controls with no history of RLS or related sleep disorders.

RESULTS

RLS patients (both treated and untreated) demonstrated reduced pain thresholds and reported greater clinical pain relative to controls. Moreover, RLS patients demonstrated enhanced temporal summation of heat pain (p<.05), which may reflect aberrant central nervous system facilitation of pain transmission. Both treated and untreated RLS patients reported disrupted sleep relative to controls, and mediation analyses suggested that the reduced pain thresholds in RLS were attributable to sleep disturbance. However, the effect of RLS on the magnitude of temporal summation of heat pain was independent of sleep disturbance.

CONCLUSIONS

These findings suggest that central nervous system pain processing may be amplified in RLS, perhaps partially as a consequence of sleep disruption. RLS patients, even those whose symptoms are managed pharmacologically, may be at elevated long-term risk for the development or maintenance of persistent pain conditions. Further studies in larger samples could help to improve the prospects for pain management in RLS patients.