Age and gender effects on heart rate activation associated with periodic leg movements in patients with restless legs syndrome

The paradoxical impact of periodic limb movements on isolated REM sleep behavior disorder patients

Recently, the α-synuclein origin and connectome model described two types of Parkinson's disease: "brain-first" and "body-first" subtypes. We aimed to investigate the role of periodic limb movements during sleep (PLMS) in identifying these subtypes starting from a prodromal stage of α-synucleinopathies. 191 patients with isolated REM sleep behavior disorder (iRBD) underwent video-polysomnography (vPSG), questionnaires, clinical interview, and neuropsychological battery. Patients who presented PLMS index (PLMSi) > 15 were compared with patients presenting PLMSi ≤ 15 on clinical questionnaires, vPSG, and neuropsychological domains with age as a covariate. Correlations were performed between PLMSi and vPSG and neuropsychological domains in both groups of iRBD. 48.2% of patients presented PLMSi > 15. iRBD subgroup with PLMSi > 15 performed better than the iRBD subgroup with PLMSi ≤ 15 in the executive function domain. In patients with PLMSi > 15 negative correlations were observed between PLMSi and some neuropsychological domains (memory, language, and executive function). Moreover, this subgroup was older and their PLMSi was positively correlated with wake-after-sleep onset and inversely correlated with total sleep time and sleep efficiency, suggesting a detrimental effect of PLM on sleep also in this cohort. Patients with PLMSi > 15 are characterized by a more preserved cognitive status, despite a more disrupted sleep. PLMSi could be explored in longitudinal studies concerning the "brain-first" and "body-first" model.

Sex and Sleep Disruption as Contributing Factors in Alzheimer's Disease

Alzheimer's disease (AD) affects more women than men, with women throughout the menopausal transition potentially being the most under researched and at-risk group. Sleep disruptions, which are an established risk factor for AD, increase in prevalence with normal aging and are exacerbated in women during menopause. Sex differences showing more disrupted sleep patterns and increased AD pathology in women and female animal models have been established in literature, with much emphasis placed on loss of circulating gonadal hormones with age. Interestingly, increases in gonadotropins such as follicle stimulating hormone are emerging to be a major contributor to AD pathogenesis and may also play a role in sleep disruption, perhaps in combination with other lesser studied hormones. Several sleep influencing regions of the brain appear to be affected early in AD progression and some may exhibit sexual dimorphisms that may contribute to increased sleep disruptions in women with age. Additionally, some of the most common sleep disorders, as well as multiple health conditions that impair sleep quality, are more prevalent and more severe in women. These conditions are often comorbid with AD and have bi-directional relationships that contribute synergistically to cognitive decline and neuropathology. The association during aging of increased sleep disruption and sleep disorders, dramatic hormonal changes during and after menopause, and increased AD pathology may be interacting and contributing factors that lead to the increased number of women living with AD.

Periodic limb movements during sleep and risk of hypertension: A systematic review

BACKGROUND

Several studies suggest an association between periodic limb movements during sleep (PLMS) and hypertension; however, a systematic evaluation of this relationship is lacking.

METHODS

We conducted a systematic review and meta-analysis of observational studies that reported odds ratio, relative risk, hazard ratio, or standardized incidence ratio, comparing the risk of hypertension in persons with PLMS (defined by the level of periodic limb movements per hour of sleep depended on individual studies) versus those without PLMS. After assessing heterogeneity and bias, the pooled risk ratio and 95% confidence intervals (CIs) were determined using a random-effect, generic inverse variance method of DerSimonian and Laird.

RESULTS

Out of 572 potentially relevant articles, six eligible studies were included in the data analysis. Studies (6 cross-sectional) included 8949 participants. The statistical heterogeneity of this study was insignificant, with an I² of 0%. A funnel plot and Egger's regression asymmetry test showed no publication bias with P-value ≥0.05. The pooled risk ratio of hypertension in patients with PLMS was 1.26 (95% CI, 1.12-1.41).

CONCLUSIONS

Our analysis demonstrates an increased hypertension risk among patients with PLMS. Prospective or interventional studies are needed to confirm this association.

[Periodic limb movements in sleep and cerebral small vessel disease progression: a prospective cohort study]

OBJECTIVE

To determine the predictive role of periodic limb movements in sleep (PLMS) in cerebral small vessel disease (cSVD) progression rate.

MATERIAL AND METHODS

Fifty patients with cSVD, aged 60-75 y.o., were enrolled. The study protocol included MRI assessment of white matter hyperintensities (WMH), nocturnal actigraphy and cognitive assessment. Depending on the PLMS, the main (PLM index ≥15) and the control (PLM index <15) groups were formed. The second visit was carried out in one year follow-up period, the examination consisted of brain MRI and cognitive assessment under the same protocol. ANCOVA was performed to determine if PLMS influence the degree of MRI- and neuropsychological changes.

RESULTS

A significant effect of PLMS on the increase in the volume of WMH was revealed, both in the form of an increase in the index by more than 15 movements per hour (p=0.03), and quantitatively in the form of a connection with the index value (p=0.048). The influence of PLMS on the progression of cognitive dysfunction has not been found, however, it has been shown that the presence of PLMS is associated with lesions in the deep white matter (r=0.42, p<0.0001), and the results of neuropsychological tests are associated with lesions in the periventricular and juxtacortical WMH (p < 0.05 for each test).

CONCLUSION

PLMS predict WMH progression in cSVD.

Myoclonus and other jerky movement disorders

Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.

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.

Periodic Leg Movements During Sleep

Periodic leg movements during sleep (PLMS) are a frequent finding in nocturnal sleep registrations that include tibialis anterior electromyographic signals. Different PLMS scoring rules exist and can have a major impact on PLMS frequency, which tends to be underappreciated. There is no consistent evidence that frequent PLMS are a causal risk factor for clinically significant outcomes. Several critical open questions are identified that need to be addressed, including but not limited to the consideration of the full range of all sleep-related leg movement activity.

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

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

Multiple asystole events in a patient undergoing total knee arthroplasty - a case report

Background

Unexpected cardiac arrest in patients during surgery is associated with high mortality. Reasons are often multifactorial and unclear.

Case presentation

This case report describes a patient who developed reversible asystole during knee surgery under general anaesthesia. All diagnostic cardiac examinations were unremarkable. After surgery, the patient showed no further symptoms.

Conclusion

To prevent cardiac arrest due to non-cardiac reasons, patients with a high risk for asystole caused by vasovagal reflex or by pain need to be identified. Preoperative conditions such as hypovolemia need to be improved prior to surgery, and additional monitoring should be used. Further investigations to determine the influence of non-cardiac disease and long-term medication are necessary.

Higher Prevalence of Hypertension among Individuals with Restless Legs Syndrome: A Meta-Analysis

OBJECTIVE

This study investigated the proposed association between restless legs syndrome (RLS) and the prevalence of hypertension.

METHODS

A meta-analysis was conducted based on searches of the PUBMED, EMBASE, Cochrane Library, and Korean electronic databases. Cohort and cross-sectional studies reporting the incidence of hypertension in individuals with RLS were included. Dichotomous data were pooled to obtain an odds ratio (OR) and 95% confidence interval (CI) for the prevalence of hypertension in individuals with RLS. The main outcome measure of the study was prevalence of hypertension in patients with RLS compared with a control group.

RESULTS

One cohort study and eight cross-sectional studies were included in the meta-analysis. Individuals with RLS had an increased prevalence of hypertension (all studies: OR=1.13, 95% CI=1.04-1.23; cross-sectional studies: OR=1.12, 95% CI=1.01-1.24). However, in subgroup analyses controlling for cardiovascular risk factors, such as diabetes mellitus and dyslipidemia, the differences in the prevalence of hypertension between RLS and control patients were no longer significant.

CONCLUSION

Patients with RLS may have a higher prevalence of hypertension, according to a pooled analysis, but the results remain to be confirmed in well-designed prospective studies.

Residual excessive sleepiness in patients with obstructive sleep apnea on treatment with continuous positive airway pressure

PURPOSE OF REVIEW

One of the most common causes of excessive daytime sleepiness in clinical practice is obstructive sleep apnea syndrome (OSAS). So far, continuous positive airway pressure (CPAP) is the most effective treatment for OSA. Some of the patients do not improve on CPAP and remain sleepy despite using CPAP.This review provides updated information about the possible causes of residual sleepiness whilst using the CPAP in patients with OSAS.

RECENT FINDINGS

Prevalence of OSAS has increased recently to 23.4% in women and 49.7% in men. Periodic limb movement, behaviorally induced insufficient sleep syndrome and depression are the most common causes of persistent sleepiness on CPAP. Residual sleepiness after exclusion of all possible causes is 6%.

SUMMARY

There is still lack of sufficient evidence about the accurate characteristics and possible causes of this residual sleepiness and how to address this in large prospective studies.

Patients with primary restless legs syndrome have higher prevalence of autonomic dysfunction and irritable bowel syndrome

INTRODUCTION

Given the limited data on autonomic dysfunction in patients with primary restless legs syndrome (pRLS), we compared autonomic dysfunction and presence of irritable bowel syndrome (IBS) between patients with pRLS and control patients.

METHODS

Consecutive adult drug-naïve patients with pRLS, and age- and gender-matched healthy control patients were enrolled in this study. Diagnoses, based on validated self-reported questionnaires, were made using the following guidelines: Rome III classification system for functional gastrointestinal disorders for IBS; Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI) for the presence of anxiety and depression, respectively; Pittsburgh Sleep Quality Index (PSQI) for severity of sleep disturbances; and Scales for Outcomes in Parkinson's disease-Autonomic (SCOPA-AUT) for autonomic dysfunction.

RESULTS

There were 88 patients with pRLS (18 male, 70 female) and 128 control patients (40 men, 88 women). The mean age of the pRLS patients and control patients was 50.3 ± 9.3 years and 49.7 ± 8.2 years, respectively. Overall, 41 (46.6%) of the patients with pRLS and 16 (12.5%) of the control patients had IBS. Among patients with pRLS, IBS was significantly more common and the total autonomic SCOPA-AUT scores were higher than those found among control patients. Among pRLS patients with IBS, total autonomic SCOPA-AUT, PSQI, BAI and BDI scores were significantly higher than among pRLS patients without IBS. The presence of IBS did not affect the severity of restless legs syndrome.

CONCLUSION

The presence of autonomic nervous system impairment in patients with pRLS and the strong link between IBS and pRLS merit further, more extensive investigation.

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.

Periodic limb movements in sleep are followed by increases in EEG activity, blood pressure, and heart rate during sleep

Purpose

Periodic limb movements in sleep (PLMS) are related to arousal, sympathetic activation, and increases in blood pressure (BP), but whether they are part of the arousal process or causative of it is unclear. Our objective was to assess the temporal distribution of arousal-related measures around PLMS.

Methods

Polysomnographic recordings of six patients with restless legs syndrome were analyzed. We analyzed 15 PLMS, plus three 5-s epochs before and after each movement, for every patient. Mean values per epoch of blood pressure (BP), heart rate (HR), and electroencephalographic (EEG) power were calculated. For each patient, six 5-s epochs of undisturbed sleep were analyzed as controls.

Results

Alpha + beta EEG power, systolic BP, and HR were significantly increased following PLMS. The EEG power and HR increases were noticed in the first epoch after PLMS, whereas that of systolic BP was observed in the second and third epochs following a PLMS. No significant changes occurred in the epochs of undisturbed sleep.

Conclusions

The results suggest that PLMS are followed by arousal-related nervous system events. Given the high frequency of PLMS throughout the night, they could be a potential risk factor for nocturnal arrhythmias and hypertension, in addition to causing sleep deprivation.

Rotigotine's effect on PLM-associated blood pressure elevations in restless legs syndrome: An RCT

Objective:

This double-blind, placebo-controlled, interventional trial was conducted to investigate the effects of rotigotine patch on periodic limb movement (PLM)–associated nocturnal systolic blood pressure (SBP) elevations.

Methods:

Patients with moderate to severe restless legs syndrome (RLS) were randomized to rotigotine (optimal dose [1–3 mg/24 h]) or placebo. Continuous beat-to-beat blood pressure (BP) assessments were performed during polysomnography at baseline and at the end of 4-week maintenance. Primary outcome was change in number of PLM-associated SBP elevations (defined as slope of linear regression ≥2.5 mm Hg/beat-to-beat interval over 5 consecutive heartbeats [≥10 mm Hg]). Additional outcomes were total SBP elevations, PLM-associated and total diastolic BP (DBP) elevations, periodic limb movements index (PLMI), and PLM in sleep arousal index (PLMSAI).

Results:

Of 81 randomized patients, 66 (37 rotigotine, 29 placebo) were included in efficacy assessments. PLM-associated SBP elevations were significantly reduced with rotigotine vs placebo (least squares mean treatment difference [95% confidence interval (CI)] −160.34 [−213.23 to −107.45]; p < 0.0001). Rotigotine-treated patients also had greater reduction vs placebo in total SBP elevations (−161.13 [−264.47 to −57.79]; p = 0.0028), PLM-associated elevations (−88.45 [−126.12 to −50.78]; p < 0.0001), and total DBP elevations (−93.81 [−168.45 to −19.16]; p = 0.0146), PLMI (−32.77 [−44.73 to −20.80]; p < 0.0001), and PLMSAI (−7.10 [−11.93 to −2.26]; p = 0.0047). Adverse events included nausea (rotigotine 23%; placebo 8%), headache (18% each), nasopharyngitis (18%; 8%), and fatigue (13%; 15%).

Conclusions:

Further investigation is required to determine whether reductions in nocturnal BP elevations observed with rotigotine might modify cardiovascular risk.

Classification of evidence:

This study provides Class I evidence that for patients with moderate to severe RLS, rotigotine at optimal dose (1–3 mg/24 h) reduced PLM-associated nocturnal SBP elevations.

A Data-Driven Analysis of the Rules Defining Bilateral Leg Movements during Sleep

STUDY OBJECTIVES

The aim of this study was to describe and analyze the association between bilateral leg movements (LMs) during sleep in subjects with restless legs syndrome (RLS), in order to eventually support or challenge the current scoring rules defining bilateral LMs.

METHODS

Polysomnographic recordings of 100 untreated patients with RLS (57 women and 43 males, mean age 57 y) were included. In each recording, we selected as reference all LMs that occurred during sleep and that were separated from another ipsilateral LM by at least 10 sec of EMG inactivity. For each reference LM and an evaluation interval from 5 sec before the onset to 5 sec after the offset of the reference LM, we evaluated (1) the presence or absence of contralateral leg movement activity and (2) the distribution of the onset-to-onset and (3) the offset-to-onset differences between bilateral LMs.

RESULTS

We selected a mean of 368 (± 222 standard deviation [SD]) reference LMs per subject. For 42% (± 22%) of the reference LMs no contralateral leg movement activity was observed within the evaluation interval. In 55% (± 22%) exactly one and in 3% (± 2%) more than one contralateral LM was observed. A further evaluation of events where exactly one contralateral LM was observed showed that in most (1) the two LMs were overlapping (93% ± 9% SD) and (2) were classified as bilateral according to the World Association of Sleep Medicine and the International Restless Legs Syndrome Study Group (WASM/ IRLSSG) (96% ± 6% SD) and (3) the American Academy of Sleep Medicine scoring rules (99% ± 2% SD). Although there was a systematic and statistically significant difference in standard LM indices during sleep based on the two different definitions of bilateral LMs, the size of the difference was not clinically meaningful (maximum individual, absolute difference in LM indices ± 2.5). In addition, we found that the duration of LMs within bilateral LM pairs was longer compared to monolateral LMs and that the duration of the single LMs in bilateral LM pairs tended to correlate.

CONCLUSIONS

The results of this study indicate that the two current standard scoring rules for the definition of bilateral LMs during sleep provide largely corresponding classifications in subjects with RLS and, in a clinical context, can be considered to be equivalent.

Periodic limb movements of sleep: empirical and theoretical evidence supporting objective at-home monitoring

INTRODUCTION

Periodic limb movements of sleep (PLMS) may increase cardiovascular and cerebrovascular morbidity. However, most people with PLMS are either asymptomatic or have nonspecific symptoms. Therefore, predicting elevated PLMS in the absence of restless legs syndrome remains an important clinical challenge.

METHODS

We undertook a retrospective analysis of demographic data, subjective symptoms, and objective polysomnography (PSG) findings in a clinical cohort with or without obstructive sleep apnea (OSA) from our laboratory (n=443 with OSA, n=209 without OSA). Correlation analysis and regression modeling were performed to determine predictors of periodic limb movement index (PLMI). Markov decision analysis with TreeAge software compared strategies to detect PLMS: in-laboratory PSG, at-home testing, and a clinical prediction tool based on the regression analysis.

RESULTS

Elevated PLMI values (>15 per hour) were observed in >25% of patients. PLMI values in No-OSA patients correlated with age, sex, self-reported nocturnal leg jerks, restless legs syndrome symptoms, and hypertension. In OSA patients, PLMI correlated only with age and self-reported psychiatric medications. Regression models indicated only a modest predictive value of demographics, symptoms, and clinical history. Decision modeling suggests that at-home testing is favored as the pretest probability of PLMS increases, given plausible assumptions regarding PLMS morbidity, costs, and assumed benefits of pharmacological therapy.

CONCLUSION

Although elevated PLMI values were commonly observed, routinely acquired clinical information had only weak predictive utility. As the clinical importance of elevated PLMI continues to evolve, it is likely that objective measures such as PSG or at-home PLMS monitors will prove increasingly important for clinical and research endeavors.

The Role of Periodic Limb Movements During Sleep in Restless Legs Syndrome: A Selective Update

Periodic leg movements during sleep (PLMS) are a highly active research topic and accumulating recent evidence has led to reevaluation of key aspects on the role of PLMS in restless legs syndrome (RLS). This article summarizes the recent developments in 3 areas: the relationship of PLMS to cortical arousals in patients with RLS, the differential effect of dopaminergic and non-dopaminergic treatment on PLMS, and the possible emergence of PLMS as a sleep-related cardiovascular risk factor.

Is autonomic nervous system involved in restless legs syndrome during wakefulness?

OBJECTIVE

To investigate cardiovascular autonomic function in patients with restless leg syndrome (RLS) by means of cardiovascular reflexes and heart rate variability (HRV) during wakefulness.

METHODS

Twelve RLS patients and 14 controls underwent cardiovascular function tests including head-up tilt test (HUTT), Valsalva maneuver, deep breathing, hand grip, and cold face. HRV analysis was performed in the frequency domain using both autoregressive (AR) and fast Fourier transform algorithms in rest supine condition and during HUTT.

RESULTS

There was a significant increase in systolic blood pressure values in supine rest condition and a trend toward a lower Valsalva ratio in RLS patients with respect to controls. The significant and physiological changes of HRV at HUTT detected in healthy subjects were not found in RLS patients.

CONCLUSION

RLS patients exhibit a tendency toward hypertension, reduced amplitude of both sympathetic and parasympathetic responses at HUTT, as well as blunted parasympathetic drive to blood pressure changes. These findings, if confirmed by more controlled studies, might support the hypothesis of autonomic nervous system involvement during wakefulness and consequently an enhanced cardiovascular risk in RLS.

Periodic limb movements during sleep and their effect on the cardiovascular system: is there a final answer?

Periodic limb movements during sleep (PLMS) is a sleep-related movement disorder characterized by repetitive limb movements during sleep, seen predominantly in the legs but also occasionally involving the arms. These movements may be associated with arousals that can lead to increases in sympathetic tone, resulting in tachycardia and elevated systolic blood pressure. Chronic sustained tachycardia and elevated systolic blood pressure are known to be associated with the development of arrhythmias, hypertension, left ventricular hypertrophy, and congestive heart failure. However, the data are not entirely clear on whether untreated PLMS is associated with these cardiovascular risks. This review examines the current evidence on whether PLMS has any effect on the cardiovascular system.

The effects of periodic limb movements in sleep (PLMS) on cardiovascular disease

Periodic limb movements in sleep (PLMS) are uncontrollable nocturnal movements that occur during sleep and increase with age. Research has implicated PLMS as a contributing factor to the development of cardiovascular disease (CVD). The purpose of this manuscript is to 1) explain the sleep disorder of PLMS and implications on CVD; 2) identify the impact of PLMS on CVD; 3) discuss treatment options for PLMS; 4) present future research needs for PLMS/RLS; 5) provide implications to health care providers to improve the care and health outcomes of persons with PLMS.

Mirtazapine provokes periodic leg movements during sleep in young healthy men

STUDY OBJECTIVES

Recent evidence suggests that certain antidepressants are associated with an increase of periodic leg movements (PLMS) that may disturb sleep. So far, this has been shown in patients clinically treated for depression and in cross-sectional studies for various substances, but not mirtazapine. It is unclear whether antidepressants induce the new onset of PLMS or only increase preexisting PLMS, and whether this is a general property of the antidepressant or only seen in depressed patients. We report here the effect of mirtazapine on PLMS in young healthy men.

DESIGN

Open-labeled clinical trial (NCT00878540) including a 3-week preparatory phase with standardized food, physical activity, and sleep-wake behavior, and a 10-day experimental inpatient phase with an adaptation day, 2 baseline days, and 7 days with mirtazapine.

SETTING

Research institute.

PARTICIPANTS

Twelve healthy young (20-25 years) men.

INTERVENTIONS

Seven days of nightly intake (22:00) of 30 mg mirtazapine.

MEASUREMENTS AND RESULTS

Sleep was recorded on 2 drug-free baseline nights, the first 2 drug nights, and the last 2 drug nights. Eight of the 12 subjects showed increased PLMS after the first dose of mirtazapine. Frequency of PLMS was highest on the first drug night and attenuated over the course of the next 6 days. Three subjects reported transient restless legs symptoms.

CONCLUSIONS

Mirtazapine provoked PLMS in 67% of young healthy males. The effect was most pronounced in the first days. The possible role of serotonergic, noradrenergic and histaminergic mechanisms in mirtazapine-induced PLMS is discussed.

Restless legs syndrome, periodic leg movements, and periodic limb movement disorder in children

The characteristic symptoms of restless legs syndrome (RLS) have been known for hundreds of years and were first reported in medicine in the 1600s. Clinicians must consider potential mimics, comorbid, and associated conditions when evaluating children with RLS symptoms. The traditional differentiation of RLS from periodic limb movement disorder (PLMD) is noted in children as well as adults. Because current pediatric RLS research is sparse, this article provides the most up-to-date evidence-based as well as consensus opinion-based information on the subject of childhood RLS and PLMD. Prevalence, pathophysiology, diagnosis, treatment, and clinical associations are discussed.

Autonomic response to periodic leg movements during sleep in narcolepsy-cataplexy

STUDY OBJECTIVES

To test the hypothesis of autonomic nervous system dysfunction in patients with narcolepsy-cataplexy (NC) by assessing the physiologic activations associated with periodic limb movements during sleep (PLMS).

DESIGN

Sleep and heart rate (HR) were recorded during 1 night of polysomnography.

SETTING

Data were collected at the Sleep Disorders Center, Sacre-Coeur Hospital, Montreal, Canada.

PARTICIPANTS

Data from 14 patients with NC (6 men, 8 women, mean age: 52.5 ± 11.9 years) were compared with data from 14 healthy control subjects matched for age and sex.

INTERVENTIONS

NA.

MEASUREMENTS AND RESULTS

Analyses included sleep stages, PLMS, microarousals, RR intervals converted into beats per minute on segments lasting 25 heartbeats (10 RR intervals before PLMS and 15 after), and cardiac-activation amplitudes. A Group-by-Heartbeat interaction was noted for PLMS without microarousals; the patients had a tachycardia of lower amplitude and a delayed and lower-amplitude bradycardia, compared with normal control subjects. Similar significant HR modifications were observed for PLMS with microarousals between patients with NC and control subjects. Patients with NC had a reduced magnitude of cardiac activation associated with PLMS with and without microarousals, as compared with control subjects. A negative correlation was noted between cardiac-activation amplitude and age in patients with NC, but no correlation with PLMS index was found in either patients with NC or control subjects.

CONCLUSION

A significant reduction in the amplitude of PLMS-related HR responses in both tachycardia and bradycardia was found in patients with NC. These findings favor the physiologic relevance of the action of hypocretin on autonomic function that may be of clinical significance, i.e., increasing the risk of cardiovascular diseases.

Restless legs syndrome

Restless legs syndrome (RLS) is a common neurological sensory-motor disorder that is characterized by intense restlessness and unpleasant creeping sensations deep inside the lower legs. Symptoms appear when the legs are at rest and are worst in the evening and at night. They force patients to keep moving their legs, and often to get out of bed and wander about. Periodic limb movements (PLMS) are also common during sleep amongst those suffering from RLS, and sleep efficiency is severely reduced. There are idiopathic as well as symptomatic forms of RLS, the latter being associated with e.g. pregnancy, iron deficiency and chronic renal failure. A family history of RLS is very common and pedigrees in these cases suggest an autosomal-dominant transmission with high penetrance. Genetic investigations have been performed in order to identify genes associated with RLS. Several loci have been found (on chromosomes 12q, 14q, 9p, 2q, 20p and 16p). Pathophysiology of RLS remains incompletely understood. However, advanced brain imaging studies and positive results of dopaminergic treatment suggest that RLS may be generated by dopamine dysfunction locally within the central nervous system. At present, there is a wide range of treatment options including levodopa, dopamine agonists, opioids, benzodiazepines, antiepileptic drugs and iron supplements.

The prevalence and significance of periodic leg movements during sleep in patients with congestive heart failure

PURPOSE

The aim of this study was to evaluate (1) the prevalence of periodic leg movements during sleep (PLMs) in a consecutive sample of congestive heart failure (CHF) outpatients; (2) the presence of correlation between PLMs, subjective daytime sleepiness, and sleep architecture; and (3) the heart rate response to PLMs in CHF.

MATERIALS AND METHODS

Seventy-nine [50 men, age 59 +/- 11 years, body mass index (BMI) 26 +/- 5 kg/m(2)] consecutive adult stable outpatients with CHF [left ventricular ejection fraction (LVEF) 36 +/- 6%] were prospectively evaluated. The patients underwent assessment of echocardiography, sleepiness (Epworth Scale), and overnight in-lab polysomnography.

RESULTS

Fifteen patients (19%) had PLM index >5. These subjects were similar in sex distribution, BMI, subjective somnolence, LVEF, and apnea-hypopnea index (AHI), but were significantly older than subjects without PLMs. Sleep architecture was similar in subjects with and without PLMs. There was a small but significant elevation of heart rate after PLMs (80.1 +/- 9.4 vs. 81.5 +/- 9.2; p < 0.001). The cardiac acceleration was also present in absence of electroencephalogram activation.

CONCLUSION

The prevalence of PLMs in consecutive sample of adult CHF outpatients was 19%. There were no differences in subjective daytime sleepiness, sleep architecture, AHI, and severity of CHF in subjects with and without PLMs. PLMs caused a small but statistically significant cardiac acceleration.

The effect of gender on autonomic and respiratory responses during sleep among both young and middle-aged subjects

BACKGROUND AND OBJECTIVES

Sleep affects the control of circulation and respiratory function. Gender and age are also known to have a profound impact on the neural control of circulation. We investigated whether gender affects sleep-related cardiovascular and respiratory responses and whether these vary according to healthy subjects being young or middle-aged.

METHODS

We studied 32 subjects: 8 women and 8 men aged 20-30 years (young), and 8 women and 8 men aged 50-60 years (middle-aged). Young women were under oral contraceptive therapy and middle-aged women were postmenopausal and not receiving hormonal replacement therapy. One-night polysomnography was used to assess RR variability during non-rapid eye movement (NREM) (stage 2) and rapid eye movement (REM) sleep. Low-frequency (LF) and high-frequency (HF) components, in normalized units (LFnu and HFnu) and LF/HF ratio were calculated on five-minute segments selected across the night and averaged for each sleep stage. The respiration frequency in NREM and REM sleep was also measured. Interaction between gender, age and sleep on autonomic and respiration variables was assessed by 2 x 2 x 2 analysis of variance (ANOVA).

RESULTS

Compared to men, women had a greater NREM-to-REM increment in LFnu (gender-by-state interaction, p<0.01), a greater decrement in HFnu (interaction, p<0.01) and a greater increment in LF/HF (interaction, p<0.05). Women also showed a more pronounced increase in respiratory frequency during REM sleep compared to men in both groups of age (gender-by-state interaction, F=7.1, p<0.05). No gender-by-age-by-state interaction was observed to affect autonomic and respiration variables.

CONCLUSION

NREM-to-REM excitatory cardiac and respiratory responses are more marked among women compared to men, regardless of their hormonal status and whether they are young or middle-aged.

CAP, epilepsy and motor events during sleep: the unifying role of arousal

Arousal systems play a topical neurophysiologic role in protecting and tailoring sleep duration and depth. When they appear in NREM sleep, arousal responses are not limited to a single EEG pattern but are part of a continuous spectrum of EEG modifications ranging from high-voltage slow rhythms to low amplitude fast activities. The hierarchic features of arousal responses are reflected in the phase A subtypes of CAP (cyclic alternating pattern) including both slow arousals (dominated by the <1Hz oscillation) and fast arousals (ASDA arousals). CAP is an infraslow oscillation with a periodicity of 20-40s that participates in the dynamic organization of sleep and in the activation of motor events. Physiologic, paraphysiologic and pathologic motor activities during NREM sleep are always associated with a stereotyped arousal pattern characterized by an initial increase in EEG delta power and heart rate, followed by a progressive activation of faster EEG frequencies. These findings suggest that motor patterns are already written in the brain codes (central pattern generators) embraced with an automatic sequence of EEG-vegetative events, but require a certain degree of activation (arousal) to become visibly apparent. Arousal can appear either spontaneously or be elicited by internal (epileptic burst) or external (noise, respiratory disturbance) stimuli. Whether the outcome is a physiologic movement, a muscle jerk or a major epileptic attack will depend on a number of ongoing factors (sleep stage, delta power, neuro-motor network) but all events share the common trait of arousal-activated phenomena.

Restless legs syndrome

BACKGROUND

The authors reviewed the clinical features, epidemiology, pathogenesis and risk factors, medical management, dental findings and dental management of patients with restless legs syndrome (RLS).

TYPES OF STUDIES REVIEWED

The authors conducted a MEDLINE search for the years 2000 through 2004 using the key terms "restless legs syndrome," "epidemiology," "pathophysiology," "treatment" and "dentistry." They selected articles published in English in peer-reviewed journals for further review, and they gave preference to articles reporting randomized controlled trials.

CONCLUSIONS

RLS is a neurological disorder that is characterized by unpleasant sensations in the legs that occur at rest, especially at bedtime. These symptoms cause an irresistible urge to get out of bed and move the legs to relieve the discomfort, thereby delaying sleep onset and resulting in fatigue and dysphoria the next day.

CLINICAL IMPLICATIONS

The prevalence of dental disease may be extensive in patients with RLS because of diminished salivary flow resulting from the medications used to treat RLS. Patient education, saliva substitutes and anticaries agents are indicated. Special precautions must be taken when prescribing or administering sedative-hypnotic agents that are likely to have adverse reactions with the medications used to treat RLS.

Effects of periodic leg movements during sleep in middle-aged subjects without sleep complaints

Recent reports have called into question the relevance of periodic leg movements during sleep disorder (PLMSD) as a specific clinical entity. Because periodic leg movement in sleep index (PLMSI) increases with age, it has become an important exclusion criterion in research on aging. However, it is unknown if PLMSI is related to sleep quality in middle-aged subjects without sleep complaints. The sleep of 70 healthy, middle-aged subjects (age 40 to 60 years) without sleep complaints was evaluated. Subjects were divided into two groups according to their PLMSI severity: (1) 43 subjects (28 women, 15 men) were in the low PLMSI group (<5) and (2) 22 subjects (9 women, 13 men) were in the high PLMSI group (>10). A significantly higher proportion of men than women showed PLMSI greater than 5. There was no significant effect of PLMSI severity group for polysomnographic sleep parameters. PLMSI exerted a small but significant effect on subjective sleep quality, especially in middle-aged men. These results raise questions about the relevance of PLMSI as a pathological index for middle-aged subjects without sleep complaints and support the notion that an increase in PLMSI may be part of the normal process of aging associated with the loss of dopaminergic function.

Mechanisms of arousal from sleep and their consequences

PURPOSE OF REVIEW

In recent years, understanding of the mechanisms by which sleep is maintained and the consequences of abnormal arousal from sleep has improved rapidly. This review describes the recent insights into the nature of sleep and arousal and the particular insights gained in common disease states such as sleep-disordered breathing.

RECENT FINDINGS

Expansion of the definitions of the classic stages of non-REM and REM sleep to include consideration of the role of cyclic alternating pattern sleep as a gating mechanism for arousal and maintenance of stable sleep has led to a significant advancement in understanding the nature of normal and pathologic arousals from sleep. In addition, the effect of arousals from sleep on cerebral cortical electrophysiology and autonomic activation has been further defined, with a potential effect on clinical practice.

SUMMARY

Arousal from sleep is dependent on wake-promoting influences overwhelming forces promoting sleep. Autonomic activation and cortical arousal can significantly affect and destabilize sleep homeostasis. The understanding of sleep-respiration interactions continues to evolve. The definition of the minimal arousal event is an important research goal. It will be important in clinical practice and research to consider sleep stability domains as a complement to sleep depth staging to allow better understanding of the relative stability and instability of the system and to consider all components of the consequences of arousal.

Influence of sleep stage and wakefulness on spectral EEG activity and heart rate variations around periodic leg movements

OBJECTIVE

Typical changes in spectral electroencephalographic (EEG) activity and heart rate (HR) have been described in periodic leg movements (PLM) associated with or without microarousals (MA). We aimed to determine the effects of sleep stage and wakefulness on these responses to ascertain whether a common pattern of EEG and HR activation takes place.

METHODS

The time course of EEG spectral activity and HR variability associated with PLM was analysed in 13 patients during light NREM sleep, rapid-eye-movement (REM) sleep and wakefulness. The same analysis was also conducted for PLM without MA occurring in stage 2.

RESULTS

A significant EEG and electrocardiogram (ECG) activation was found associated with PLM during sleep, but not during wakefulness. While in light NREM sleep, an increase in delta and theta bands was detected before the PLM onset, in REM sleep the EEG activation occurred simultaneously with the PLM onset. Moreover, during stage 1 and REM sleep, alpha and fast frequencies tended to remain sustained after the PLM onset. In contrast, during wakefulness, a small and not significant increase in cerebral activity was present, starting at the PLM onset and persisting in the post-movement period. A typical pattern of cardiac response was present during NREM and REM sleep, the autonomic activation being lesser and prolonged during wakefulness.

CONCLUSIONS

We conclude that the EEG and HR responses to PLM differ between sleep stages and wakefulness with lesser changes found during wakefulness.

SIGNIFICANCE

These findings suggest that specific sleep state-dependent mechanisms may underlie the occurrence of PLM.

The clinical neurophysiology of the restless legs syndrome and periodic limb movements. Part I: diagnosis, assessment, and characterization

OBJECTIVE

The restless legs syndrome is a common sensorimotor disorder impacting on sleep which has been known for centuries, but only recently become recognized as a significant clinical and pathophysiological problem. The definition of RLS has evolved until certain key clinical features have been defined as diagnostic, while others are strongly associated: the urge to move is seen as primary. Epidemiology suggests ethnic variation with highest frequency in populations of European origin; family and genetic studies support a genetic basis to many idiopathic cases while links to secondary disorders usually involving low iron stores are also known. Abnormalities of brain iron transport and consequent dysfunction of the dopamine system are suspected sources of the disorder.

METHODS

The literature was searched for all references relating clinical neurophysiologic investigations to the diagnosis, assessment, and characterization of RLS.

RESULTS

RLS is defined clinically and diagnosed by medical history while its frequent concomitant, periodic limb movements (PLM), must be diagnosed by polysomnography or movement recording. Severity of RLS is generally assessed by subjective measures, but sleep recording and measurement of PLM frequency and association with sleep disruption are also used to measure severity. A provocative test, the suggested immobilization test, can also be used with both subjective and movement recording. RLS and PLM in RLS are both associated with the circadian cycle and are maximal early in the sleep period. PLM appear to be associated both with unstable EEG phases involving the cyclic alternating pattern and cyclical autonomic changes whose initiation may precede the muscle activity.

CONCLUSIONS

While RLS remains a subjective disorder, neurophysiologic measures have been important, especially for assessment. Ambulatory methodologies may offer the most accurate and economical means of assessing motor activity as a key marker of RLS and of accurately measuring PLM from night to night. As the pathophysiology of RLS is better understood, more focused techniques may be developed to measure its presence and severity in individual patients.