Periodic leg movements during sleep and periodic limb movement disorder in patients presenting with unexplained insomnia

Elevated periodic limb movement index is associated with hypoxemia in children with early onset scoliosis

PURPOSE

Patients with early onset scoliosis are at high risk of sleep disordered breathing, sleep disruption, and adverse consequences of poor sleep. In this study, we aim to assess the prevalence of periodic limb movements of sleep in a cohort of children with early onset scoliosis and identify factors that correlate with the presence of periodic limb movements.

METHODS

This is a retrospective chart review of 40 patients with EOS (ages 1-17 years) who underwent a PSG from 2003 through 2019. Data collected included age, sex, and polysomnography parameters. Descriptive statistics were used: independent T test and Pearson correlation.

RESULTS

The average age was 9.6 years (SD 5.2); 22 were female. Eleven patients (27.5%) had elevated periodic limb movement index (PLMI) (≥ 5). Those with PLMI ≥ 5 had arousal index of 15.4 (SD 7.2) and those with normal PLMI having an arousal index of 9.4 (SD 4.9); this reached statistical significance (p < 0.05). Those with elevated PLMI spent 4.9 (SD 8.3) minutes with saturations below 88%, while those with normal PLMI spent 1.0 (SD 1.8); this was statistically significant. There was a moderate positive correlation between arousal index, hypoxemia, and PLMI.

CONCLUSION

The study suggests that children with early onset scoliosis have higher frequency of periodic limb movements during sleep, and these may be correlated with increased arousal and with hypoxemia.

The dynamics of cyclic-periodic phenomena during non-rapid and rapid eye movement sleep

Sleep is a complex physiological state characterized by distinct stages, each exhibiting unique electroencephalographic patterns and physiological phenomena. Sleep research has unveiled the presence of intricate cyclic-periodic phenomena during both non-rapid eye movement and rapid eye movement sleep stages. These phenomena encompass a spectrum of rhythmic oscillations and periodic events, including cyclic alternating pattern, periodic leg movements during sleep, respiratory-related events such as apneas, and heart rate variability. This narrative review synthesizes empirical findings and theoretical frameworks to elucidate the dynamics, interplay and implications of cyclic-periodic phenomena within the context of sleep physiology. Furthermore, it invokes the clinical relevance of these phenomena in the diagnosis and management of sleep disorders.

Changes in time structure of periodic leg movements during sleep in restless legs syndrome: Effects of sex and age

BACKGROUND

The objective of this study was to check the hypothesis that in women with restless legs syndrome (RLS) different changes occur in periodic leg movements during sleep (PLMS) during the post-menopausal period (using >50 years as a proxy) than in men of the same age.

METHODS

We recruited 36 untreated patients aged 18-50 years (19 men, median age 40 years, and 17 women, median age 37 years) while the remaining 67 were >50 years old (24 men, median age 66.6 years, and 43 women, median age 60.0 years). Leg movement activity during sleep was analyzed by means of an approach utilizing indexes especially suitable to assess leg movement periodicity.

RESULTS

No significant difference was seen between men in the two age groups; conversely, in women, a clear and significant increase in Periodicity Index was observed in the older group, along with a decrease in isolated leg movements. In women, a clear age-related enhancement of PLMS was found in the intermovement interval graphs, especially in the 16-22 s range, which was more evident than that observed in men. The results remained unchanged also when they were replicated by selecting only subjects aged 18-45 years vs. those aged >55 years.

CONCLUSIONS

Our findings indicate that assessing PLMS in women after menopause is clinically relevant because they are probably connected with the hormonal fluctuations of this period of life. Translationally, identifying and addressing PLMS in post-menopausal women is crucial for optimizing their sleep health and addressing potential health risks associated with sleep disturbances.

Polysomnographic features of idiopathic restless legs syndrome: a systematic review and meta-analysis of 13 sleep parameters and 23 leg movement parameters

STUDY OBJECTIVES

This study aims to explore the polysomnographically measured sleep and leg movement differences between idiopathic restless legs syndrome (RLS) patients and healthy controls.

METHODS

An electronic literature search was conducted in EMBASE, MEDLINE, all EBM databases, CINAHL, and PsycINFO. Only observational case-control studies were included in the meta-analysis. The differences in 13 sleep parameters and 23 leg movement parameters between RLS patients and healthy controls were explored.

RESULTS

Thirty-eight studies were identified for systematic review, 31 of which were used for meta-analysis. Meta-analyses revealed significant reductions in total sleep time, sleep efficiency, stage N2 and rapid eye movement (REM) sleep percentages, and increases in wake time after sleep onset, stage shifts per hour, stage N1 percentage, REM latency, arousal index, and apnea-hypopnea index. Some leg movement parameters, such as periodic limb movement during sleep (PLMS) index, PLMS sequence duration, number of PLMS sequence, and periodicity index, were higher in RLS patients compared with healthy controls. Further, our meta-analysis revealed a higher PLMS index during non-REM sleep compared with that during REM sleep.

CONCLUSIONS

RLS patients manifest a lightening of sleep, increased sleep fragmentation, and greater sleep-related breathing disruption and limb movements during sleep relative to healthy normal individuals. The distributions of PLMS during a night's sleep may provide more information to clarify the specific characteristics of leg movements in RLS. PLMS in RLS are concentrated in non-REM sleep. The periodicity index may be a more sensitive and specific marker of RLS than the PLMS index.

CITATION

Zhang H, Zhang Y, Ren R, et al. Polysomnographic features of idiopathic restless legs syndrome: a systematic review and meta-analysis of 13 sleep parameters and 23 leg movement parameters. J Clin Sleep Med. 2022;18(11):2561-2575.

Sleep medicine: Practice, challenges and new frontiers

Sleep medicine is an ambitious cross-disciplinary challenge, requiring the mutual integration between complementary specialists in order to build a solid framework. Although knowledge in the sleep field is growing impressively thanks to technical and brain imaging support and through detailed clinic-epidemiologic observations, several topics are still dominated by outdated paradigms. In this review we explore the main novelties and gaps in the field of sleep medicine, assess the commonest sleep disturbances, provide advices for routine clinical practice and offer alternative insights and perspectives on the future of sleep research.

Polysomnographic nighttime features of Restless Legs Syndrome: A systematic review and meta-analysis

Background

Restless Legs Syndrome (RLS) is a common sleep disorder. Polysomnographic (PSG) studies have been used to explore the night sleep characteristics of RLS, but their relationship with RLS has not been fully analyzed and researched.

Methods

We searched the Cochrane Library electronic literature, PubMed, and EMBASE databases to identify research literature comparing the differences in polysomnography between patients with RLS and healthy controls (HCs).

Results

This review identified 26 studies for meta-analysis. Our research found that the rapid eye movement sleep (REM)%, sleep efficiency (SE)%, total sleep time (TST) min, and N2 were significantly decreased in patients with RLS compared with HCs, while sleep latency (SL) min, stage shifts (SS), awakenings number (AWN), wake time after sleep onset (WASO) min, N1%, rapid eye movement sleep latency (REML), and arousal index (AI) were significantly increased. Additionally, there was no significant difference among N3%, slow wave sleep (SWS)%, and apnea-hypopnea index (AHI).

Conclusion

Our findings demonstrated that architecture and sleep continuity had been disturbed in patients with RLS, which further illustrates the changes in sleep structure in patients with RLS. In addition, further attention to the underlying pathophysiological mechanisms of RLS and its association with neurodegenerative diseases is needed in future studies.

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.

Patient characteristics and compliance with positive airway pressure therapy during New York City's 2020 COVID-19 pandemic stay-at-home orders: The NYU comprehensive epilepsy center-sleep center telemedicine experience

Objectives

We sought to evaluate the success of telemedicine during New York City's COVID-19 pandemic stay-at-home period, and understand the distribution of sleep complaints seen. We also compared positive airway pressure (PAP) therapy compliance for a random patient sample to determine whether the pandemic influenced PAP usage.

Methods

Encounters from the stay-at-home period were reviewed for patient characteristics and clinician impressions, and were compared to administrative data from the prior 2.5 months (“control” period). PAP compliance was compared between the periods for a randomly selected group of forty patients.

Results

The telemedicine show rate was 89.37%. Sleep apnea then insomnia were the predominant diagnoses. Insomnia complaints were higher during the stay-at-home period. PAP compliance and AHI were similar between the periods.

Conclusions

Sleep apnea and insomnia were common complaints; insomnia was significantly more common during the pandemic. PAP compliance was similar between the two periods for a randomly selected cohort.

Tobacco-induced sleep disturbances: A systematic review and meta-analysis

Even though tobacco-induced sleep disturbances (TISDs) have been reported in previous studies, the present article is the first meta-analysis quantitatively assessing the impact of tobacco on sleep parameters. We conducted a systematic review and meta-analysis of the studies comparing objective (i.e. polysomnography and actigraphy) and/or subjective sleep parameters in chronic tobacco smokers without comorbidities versus healthy controls. Studies were retrieved using PubMed, PsycINFO, and Web of Science. Differences are expressed as standardized mean deviations (SMD) and their 95% confidence intervals (95%CI). Fourteen studies were finally included into the review, among which ten were suitable for meta-analysis. Compared to healthy controls, chronic tobacco users displayed increased N1 percentage (SMD = 0.65, 95%CI: 0.22 to 1.07), N2 percentage (SMD = 1.45, 95%CI: 0.26 to 2.63), wake time after sleep onset (SMD = 6.37, 95%CI: 2.48 to 10.26), and decreased slow-wave sleep (SMD = -2.00, 95%CI: -3.30 to -0.70). Objective TISDs preferentially occurred during the first part of the night. Regarding subjective parameters, only the Pittsburgh Sleep Quality Index (PSQI) total score could be analyzed, with no significant between-groups difference (SMD = 0.53, 95%CI: -0.18 to 1.23). Smoking status should be carefully assessed in sleep medicine, while TISDs should be regularly explored in chronic tobacco users.

The Clinical Evaluation of Sleep-Related Movement Disorders

This article is a comprehensive review of the clinical evaluation of sleep-related movement disorders. In this review, the authors present a practical approach to help clinicians identify the "pattern recognition" of movement and behavior disorders during sleep, with the process of translating a particular movement that occurs when asleep, with clinically classifying disorders, and with obtaining an etiologic diagnosis. The aim is not to provide an exhaustive review of the literature, but to concentrate on the most important symptoms, so the clinical approach can be improved and the best choices can be made during the diagnostic process.

Comorbidities in children with elevated periodic limb movement index during sleep

STUDY OBJECTIVES

Little is known about comorbidities in children who have elevated periodic limb movement index (PLMI) during overnight polysomnogram (PSG). The aim of this study is to identify comorbidities in children with elevated PLMI (PLMI > 5) versus children with PLMI < 5 presenting to a pediatric sleep center.

METHODS

This study was a retrospective review of all clinically indicated PSGs obtained consecutively from 3/2017-3/2019 at Seattle Children's Sleep Disorders Center. Data collected included demographics, clinical presentation, medications, medical history, family history specifically for restless legs syndrome (RLS), ferritin levels, and PSG metrics. Characteristics between those with (cases) elevated PLMI (AASM criteria) and without (controls) were summarized.

RESULTS

We identified 148 subjects with elevated PLMI (67% male, mean age 7.95 years, range 1-20), yielding a PLMI > 5 prevalence of 5%. There were 188 controls included (58% male, mean age 8.0 years, range 1-19). Neither sex (chi-square = 2.8, NS) nor age (Mann-Whitney U = 1339.5, NS) differed between groups. Case subjects had a higher prevalence of RLS, snoring, insomnia, mood disorders, behavioral problems, morning headaches, chronic kidney disease, epilepsy, and chronic heart disease. Similarly, the use of antidepressants, antipsychotics, antiseizure medication, and other medications was statistically more frequent in children with elevated PLMS. The prevalence of PLMI > 5 was 5% and the prevalence of periodic limb movement disorder (PLMD) was 0.3% in children referred to polysomnography. Ferritin levels did not differ.

CONCLUSIONS

We identified the prevalence of PLMD in a sleep medicine-referred population. We have also identified comorbidities and medications associated with elevated PLMI in children.No clinical trial.

Restless Legs Syndrome and Periodic Limb Movements in 86 patients with Multiple Sclerosis

STUDY OBJECTIVES

To assess the frequency of restless legs syndrome (RLS), periodic limb movements during sleep (PLMS) and their overlap in a large sample of patients with multiple sclerosis (MS). To compare clinical and paraclinical findings among four sub-groups of patients: RLS-/PLMS- (patients without RLS and PLMS), RLS+/PLMS- (patients with RLS and without PLMS), RLS-/PLMS (patients without RLS and with PLMS), RLS+/PLMS+ (patients with both RLS and PLMS).

METHODS

In this cross-sectional, observational, instrumental study, eighty-six patients (M/F: 27/59; mean age 48.0 ± 10.8 years) with a diagnosis of MS underwent a telephone interview assessing the five standard diagnostic criteria for RLS. Seventy-six participants underwent polysomnography (PSG) and maintenance of wakefulness test. Instrumental and clinical findings were subsequently statistically compared to investigate their association with RLS and PLMS index (PLMSI).

RESULTS

RLS and PLMS (PLMSI ≥15/h) frequency in patients with MS was of 31.4% and 31.6% respectively. Among patients with RLS, 37.5% had a PLMSI ≥15/h. RLS-/PLMS+ group showed higher wake after sleep onset (p = 0.01), stage shifts per hour (p = 0.03), increased stage N1 (p = 0.03) and reduction in stage N3 (p = 0.01) compared to RLS-/PLMS-. RLS had no influence on clinical and PSG parameters (p = 0.45).

CONCLUSIONS

RLS is highly frequent in patients with MS. The frequency of PLMS is comparable to the general population. The low percentage of patients with RLS having a high PLMSI, together with the absence of correlation between RLS and female gender and older age, support the existence of a distinct symptomatic form of RLS in MS.

Insomnia Patients With Subjective Short Total Sleep Time Have a Boosted Response to Cognitive Behavioral Therapy for Insomnia Despite Residual Symptoms

Background: Two distinct insomnia disorder (ID) phenotypes have been proposed, distinguished on the basis of an objective total sleep time less or more than 6 hr. In particular, it has been recently reported that patients with objective short sleep duration have a blunted response to cognitive behavioral therapy for insomnia (CBT-I). The aim of this study was to investigate the differences of CBT-I response in two groups of ID patients subdivided according to total sleep time. Methods: Two hundred forty-six ID patients were subdivided into two groups, depending on their reported total sleep time (TST) assessed by sleep diaries. Patients with a TST greater than 6 hr were classified as "normal sleepers" (NS), while those with a total sleep time less than 6 hr were classified as "short sleepers" (SS). Results: The delta between Insomnia Severity Index scores and sleep efficiency at the beginning as compared to the end of the treatment was significantly higher for SS in comparison to NS, even if they still exhibit more insomnia symptoms. No difference was found between groups in terms of remitters; however, more responders were observed in the SS group in comparison to the NS group. Conclusions: Our results demonstrate that ID patients with reported short total sleep time had a beneficial response to CBT-I of greater magnitude in comparison to NS. However, these patients may still experience the presence of residual insomnia symptoms after treatment.

Effect of changes in periodic limb movements under cpap on adherence and long term compliance in obstructive sleep apnea

Purpose of the study Periodic leg movements (PLMs) are found in 30% of patients suffering from OSA. Under CPAP, we observed that PLMs can increase, decrease, or remain unchanged. The predictors of these changes are not well established. Objective To determine the predictors of PLMs change under CPAP and its impact on long-term adherence. Materials and method The patients were referred to the sleep laboratory for snoring or sleepiness. A single PSG night has been performed before and after CPAP treatment. Data on medication used, comorbidities and ferritin level were collected. Results A total of 160 patients were recruited with a severe OSA. About 32.5% (52/160) patients had emerging PLM i.e. that appeared after the disappearance of respiratory events. By comparing patients with emerging-PLMs to others, we found that only the blood ferritin level was significantly different between groups. Moreover, after one-year follow-up, a significant difference in adherence and long-term compliance was observed between patients without PLM at both screening and CPAP polysomnographies or emerging PLM at the second study (56%) vs. patients with baseline PLM, whether PLM remained stable or decreased under CPAP treatment (75%) (p-value 0.028). Serum ferritin and presence of diabetes mellitus predicted the evolution of PLM observed. Patients with low ferritin levels demonstrated an increase of PLM after initiation of nasal CPAP treatment. Conclusion The emergence of PLM negatively impacts long-term adherence to nasal CPAP treatment in OSA. Blood ferritin level is a predictor of the evolution of PLM under CPAP therapy.

Leg Movement Activity During Sleep in Adults With Attention-Deficit/Hyperactivity Disorder

Objectives: To conduct a first detailed analysis of the pattern of leg movement (LM) activity during sleep in adult subjects with Attention-Deficit/Hyperactivity Disorder (ADHD) compared to healthy controls. Methods: Fifteen ADHD patients and 18 control subjects underwent an in-lab polysomnographic sleep study. The periodic character of LMs was evaluated with established markers of "periodicity," i.e., the periodicity index, intermovement intervals, and time distribution of LM during sleep, in addition to standard parameters such as the periodic leg movement during sleep index (PLMSI) and the periodic leg movement during sleep arousal index (PLMSAI). Subjective sleep and psychiatric symptoms were assessed using several, self-administered, screening questionnaires. Results: Objective sleep parameters from the baseline night did not significantly differ between ADHD and control subjects, except for a longer sleep latency (SL), a longer duration of the periodic leg movements during sleep (PLMS) in REM sleep and a higher PLMSI also in REM sleep. Data from the sleep questionnaires showed perception of poor sleep quality in ADHD patients. Conclusions: Leg movements during sleep in ADHD adults are not significantly more frequent than in healthy controls and the nocturnal motor events do not show an increased periodicity in these patients. The non-periodic character of LMs in ADHD has already been shown in children and seems to differentiate ADHD from other pathophysiological related conditions like restless legs syndrome (RLS) or periodic limb movement disorder (PLMD). The reduced subjective sleep quality reported by ADHD adults contrasted with the normal objective polysomnographic parameters, which could suggest a sleep-state misperception in these individuals or more subtle sleep abnormalities not picked up by the traditional sleep staging.

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.

A Relationship between Periodic Limb Movements in Sleep and High Nocturnal Blood Pressure Values in Patients with Insomnia

STUDY OBJECTIVES

Insomnia, which is the most common sleep disorder, is a significant public health burden. Growing evidence suggests the existence of a relationship between insomnia and hypertension. The aim of this study was to verify the hypothesis that periodic limb movements in sleep (PLMS) are related to increased nocturnal blood pressure (BP) values in patients with insomnia.

METHODS

We retrospectively analyzed polysomnographic recordings of patients with insomnia who were seen in our clinic from January to December 2012. Patients were divided into two groups based on their nocturnal BP values: group I had normal nocturnal BP values (n = 27) and group II (n = 29) had elevated nocturnal BP values. The sleep architecture of the groups was compared.

RESULTS

The groups did not differ in terms of age, sex, or the prevalence of cardiovascular disorders. However, we found that the number of PLMS was significantly higher in group II than in group I (PLMS index: 18.8 vs. 6.5; p = 0.01).

CONCLUSIONS

Our results suggest that PLMS are related to increased nocturnal BP values in patients with insomnia, which may partly explain the relationship between insomnia and hypertension. Therefore, it is possible that treatment of PLMS may normalize nocturnal BP in patients with insomnia.

Sleep Perception in Obstructive Sleep Apnea: A Study Using Polysomnography and the Multiple Sleep Latency Test

Background and Purpose

Discrepancies between objectively measured sleep and subjective sleep perception in patients with insomnia have been reported. However, few studies have investigated sleep-state misperception in patients with obstructive sleep apnea (OSA). We designed this study to 1) delineate the factors that could affect this discrepancy and 2) infer an underlying mechanism in patients with OSA.

Methods

We recruited patients who visited our sleep clinic for the evaluation of their snoring and/or observed OSA. Participants completed a structured questionnaire and underwent overnight polysomnography. On the following day, five sessions of the multiple sleep latency test (MSLT) were applied. We divided the patients into two groups: normal sleep perception and abnormal perception. The abnormal-perception group included patients whose perceived total sleep time was less than 80% of that measured in polysomnography.

Results

Fifty OSA patients were enrolled from a university hospital sleep clinic. Excessive daytime sleepiness, periodic limb movement index (PLMI), and the presence of dreaming were positively associated with poor sleep perception. REM sleep near the sleep termination exerted important effects. Respiratory disturbance parameters were not related to sleep perception. There was a prolongation in the sleep latency in the first session of the MSLT and we suspected that a delayed sleep phase occurred in poor-sleep perceivers.

Conclusions

As an objectively good sleep does not match the subjective good-sleep perception in OSA, physicians should keep in mind that OSA patients who perceive that they have slept well does not mean that their OSA is less severe.

Periodic leg movement (PLM) monitoring using a distributed body sensor network

Wireless sensors networks represent the architecture of choice for distributed monitoring due to the ease of deployment and configuration. We developed a distributed sleep monitoring system which combines wireless inertial sensors SP-10C by Sensoplex controlled by a custom smartphone application as an extension of the polysomnographic (PSG) monitor SOMNOscreen plus from Somnomedics. While existing activity monitors are wired to the SOMNOscreen, our system allows the use of wireless inertial sensors to improve user's comfort during sleep. The system is intended for monitoring of periodic leg movements (PLM) and user's activity during sleep. Wireless sensors are placed on ankle and toes of the foot in a customized sock. An Android app communicates with wireless sensors over Bluetooth Smart (BTS) link and streams 3D accelerometer values, 4D unit quaternion values and timestamps. In this paper we present a novel method of synchronization of data streams from PSG and inertial sensors, and original method of detection of PLM events. The system was tested using five experiments of simulated PLM, and achieved 96.51% of PLM detection accuracy.

Physiological time structure of the tibialis anterior motor activity during sleep in mice, rats and humans

The validation of rodent models for restless legs syndrome (Willis-Ekbom disease) and periodic limb movements during sleep requires knowledge of physiological limb motor activity during sleep in rodents. This study aimed to determine the physiological time structure of tibialis anterior activity during sleep in mice and rats, and compare it with that of healthy humans. Wild-type mice (n = 9) and rats (n = 8) were instrumented with electrodes for recording the electroencephalogram and electromyogram of neck muscles and both tibialis anterior muscles. Healthy human subjects (31 ± 1 years, n = 21) underwent overnight polysomnography. An algorithm for automatic scoring of tibialis anterior electromyogram events of mice and rats during non-rapid eye movement sleep was developed and validated. Visual scoring assisted by this algorithm had inter-rater sensitivity of 92-95% and false-positive rates of 13-19% in mice and rats. The distribution of the time intervals between consecutive tibialis anterior electromyogram events during non-rapid eye movement sleep had a single peak extending up to 10 s in mice, rats and human subjects. The tibialis anterior electromyogram events separated by intervals <10 s mainly occurred in series of two-three events, their occurrence rate in humans being lower than in mice and similar to that in rats. In conclusion, this study proposes reliable rules for scoring tibialis anterior electromyogram events during non-rapid eye movement sleep in mice and rats, demonstrating that their physiological time structure is similar to that of healthy young human subjects. These results strengthen the basis for translational rodent models of periodic limb movements during sleep and restless legs syndrome/Willis-Ekbom disease.

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

STUDY OBJECTIVES

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

SETTING

Sleep research center.

PATIENTS

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

METHODS

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

MEASUREMENTS AND RESULTS

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

CONCLUSION

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

Periodic limb movements during REM sleep in multiple sclerosis: a previously undescribed entity

BACKGROUND

There are few studies describing periodic limb movement syndrome (PLMS) in rapid eye movement (REM) sleep in patients with narcolepsy, restless legs syndrome, REM sleep behavior disorder, and spinal cord injury, and to a lesser extent, in insomnia patients and healthy controls, but no published cases in multiple sclerosis (MS). The aim of this study was to investigate PLMS in REM sleep in MS and to analyze whether it is associated with age, sex, disability, and laboratory findings.

METHODS

From a study of MS patients originally published in 2011, we retrospectively analyzed periodic limb movements (PLMs) during REM sleep by classifying patients into two subgroups: PLM during REM sleep greater than or equal to ten per hour of REM sleep (n=7) vs less than ten per hour of REM sleep (n=59). A univariate analysis between PLM and disability, age, sex, laboratory findings, and polysomnographic data was performed.

RESULTS

MS patients with more than ten PLMs per hour of REM sleep showed a significantly higher disability measured by the Kurtzke expanded disability status scale (EDSS) (P=0.023). The presence of more than ten PLMs per hour of REM sleep was associated with a greater likelihood of disability (odds ratio 22.1; 95% confidence interval 3.5-139.7; P<0.0001), whereas there were no differences in laboratory and other polysomnographic findings.

CONCLUSION

PLMs during REM sleep were not described in MS earlier, and they are associated with disability measured by the EDSS.

Louis EK, Duwell EJ, Timm PC, Sandness DJ, Boeve BF, Silber MH. Diagnostic thresholds for quantitative REM sleep phasic burst duration, phasic and tonic muscle activity, and REM atonia index in REM sleep behavior disorder with and without comorbid obstructive sleep apnea

OBJECTIVES

We aimed to determine whether phasic burst duration and conventional REM sleep without atonia (RSWA) methods could accurately diagnose REM sleep behavior disorder (RBD) patients with comorbid OSA.

DESIGN

We visually analyzed RSWA phasic burst durations, phasic, "any," and tonic muscle activity by 3-s mini-epochs, phasic activity by 30-s (AASM rules) epochs, and conducted automated REM atonia index (RAI) analysis. Group RSWA metrics were analyzed and regression models fit, with receiver operating characteristic (ROC) curves determining the best diagnostic cutoff thresholds for RBD. Both split-night and full-night polysomnographic studies were analyzed.

SETTING

N/A.

PARTICIPANTS

Parkinson disease (PD)-RBD (n = 20) and matched controls with (n = 20) and without (n = 20) OSA.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

All mean RSWA phasic burst durations and muscle activities were higher in PD-RBD patients than controls (P < 0.0001), and RSWA associations with PD-RBD remained significant when adjusting for age, gender, and REM AHI (P < 0.0001). RSWA muscle activity (phasic, "any") cutoffs for 3-s mini-epoch scorings were submentalis (SM) (15.5%, 21.6%), anterior tibialis (AT) (30.2%, 30.2%), and combined SM/AT (37.9%, 43.4%). Diagnostic cutoffs for 30-s epochs (AASM criteria) were SM 2.8%, AT 11.3%, and combined SM/AT 34.7%. Tonic muscle activity cutoff of 1.2% was 100% sensitive and specific, while RAI (SM) cutoff was 0.88. Phasic muscle burst duration cutoffs were: SM (0.65) and AT (0.79) seconds. Combining phasic burst durations with RSWA muscle activity improved sensitivity and specificity of RBD diagnosis.

CONCLUSIONS

This study provides evidence for REM sleep without atonia diagnostic thresholds applicable in Parkinson disease-REM sleep behavior disorder (PD-RBD) patient populations with comorbid OSA that may be useful toward distinguishing PD-RBD in typical outpatient populations.

Increased electroencephalographic high frequencies during the sleep onset period in patients with restless legs syndrome

STUDY OBJECTIVES

To analyze the electroencephalographic (EEG) spectral content in untreated patients with restless legs syndrome (RLS) during the sleep onset period (SOP) and during the quiet wakefulness preceding sleep, in order to test the hypothesis that a state of hyperarousal might be present during the SOP with RLS.

SETTING

Sleep Research Centre.

PATIENTS

Twenty-seven untreated consecutive patients with RLS (mean age = 53.6 y), 11 untreated consecutive patients with primary insomnia (mean age = 58.9 y), and 14 normal controls (mean age = 50.3 y).

METHODS

SOP was defined as the 10-min period centered with the occurrence of the first sleep spindle in the EEG, and then subdivided into SOP-1 (period of 5 min before the first spindle) and SOP-2 (period of 5 min following). Leg movements occurring during SOP were counted and used as a covariate in the statistical analysis. Also, one period of 1 min of artifact-free quiet wakefulness after lights off was identified. EEG spectral analysis was run during these periods using the C3/A2 or C4/A1 channel.

MEASUREMENTS AND RESULTS

Increased EEG alpha and beta bands and/or beta/delta ratio in RLS versus normal controls, during both wakefulness preceding sleep and SOP (both parts SOP-1 and SOP-2) were found, which were, however, smaller than the increases found in patients with insomnia.

CONCLUSION

The results of this study support the hypothesis of the presence of a state of hyperarousal in restless legs syndrome (RLS) during the sleep onset period. Treatment for RLS might need to take these findings into consideration.

CITATION

Ferri R, Cosentino FI, Manconi M, Rundo F, Bruni O, Zucconi M. Increased electroencephalographic high frequencies during the sleep onset period in patients with restless legs syndrome.

Respiratory-related leg movements and their relationship with periodic leg movements during sleep

STUDY OBJECTIVES

To describe the time structure of leg movements (LM) in obstructive sleep apnea (OSA) syndrome, in order to advance understanding of their clinical significance.

LOCATION

Sleep Research Centre, Oasi Institute (IRCCS), Troina, Italy.

SETTING

Sleep laboratory.

PATIENTS

Eighty-four patients (16 females, 68 males, mean age 55.1 y, range 29-74 y).

METHODS

Respiratory-related leg movements (RRLM) and those unrelated to respiratory events (NRLM) were examined within diagnostic polysomnograms alone and together for their distributions within the sleep period and for their periodicity.

MEASUREMENTS AND RESULTS

Patients with OSA and RRLM exhibited more periodic leg movements in sleep (PLMS), particularly in NREM sleep. A gradual decrease in number of NRLM across the sleep period was observed in patients with RRLM. This pattern was less clear for RRLM. Frequency histograms of intermovement intervals of all LMs in patients with RRLM showed a prominent first peak at 4 sec, and a second peak at approximately 24 sec coincident with that of PLMS occurring in the absence of OSA. A third peak of lowest amplitude was the broadest with a maximum at approximately 42 sec. In patients lacking RRLM, NRLM were evident with a single peak at 2-4 sec. A stepwise linear regression analysis showed that, after controlling for a diagnosis of restless legs syndrome and apnea-hypopnea index, PLMS remained significantly associated with RRLM.

CONCLUSION

The time structure of leg movements occurring in conjunction with respiratory events exhibit features of periodic leg movements in sleep occurring alone, only with a different and longer period. This brings into question the validity, both biologic and clinical, of scoring conventions with their a priori exclusion from consideration as periodic leg movements in sleep.

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.

Restless legs syndrome: impact on sleep-related breathing disorders

Restless legs syndrome (RLS) is a common chronic sensory-motor neurological disorder that remains a clinical diagnosis. Most RLS patients present with sleep complaints in the form of initiation and/or maintenance insomnia as RLS has a circadian rhythmicity. An increased number of periodic leg movements during sleep (PLMS) is a supportive criterion in the diagnosis of RLS. Abnormalities in the central dopaminergic and iron systems are involved in the physiopathology of RLS. There is a higher prevalence of RLS and PLMS in sleep-disordered breathing patients, particularly those with obstructive sleep apnoea (OSA), the most common sleep disorder in western societies. The complex mechanisms underlying the association between OSA, RLS and PLMS remain unclear. Untreated OSA can lead to adverse cardiovascular consequences due to cardio-metabolic dysfunction. It remains controversial whether RLS could further adversely impact the cardiovascular consequences of OSA. The PLMS do not have an additive effect on the hypersomnia experienced by some sleep-disordered breathing patients. Continuous positive airway pressure (CPAP) therapy is the most effective therapy for OSA. The presence of PLMS during CPAP treatment could be a marker of an incomplete resolution of sleep-disordered breathing in the form of increased upper airway resistance syndrome, despite treatment. Dopaminergic agonists are the preferred agent for the treatment of RLS, and are indicated when RLS symptoms are frequent and affect quality of life. PLMS and RLS do not seem to contribute to the residual hypersomnia that can be observed in some sleep-disordered breathing patients despite adequate compliance and effective CPAP therapy.

Regensburg Insomnia Scale (RIS): a new short rating scale for the assessment of psychological symptoms and sleep in insomnia; study design: development and validation of a new short self-rating scale in a sample of 218 patients suffering from insomnia and 94 healthy controls

Background

The Regensburg Insomnia Scale (RIS) is a new self-rating scale to assess cognitive, emotional and behavioural aspects of psychophysiological insomnia (PI) with only ten items. A specific purpose of the new scale is the evaluation of the outcome of insomnia- specific cognitive behaviour therapy (CBT-I).

Methods

Internal consistency of the RIS has been validated in 218 patients with PI. For determining sensitivity and specificity, this sample has been compared to 94 healthy controls. Sensitivity to change and pre-post cross-validation with the Pittsburgh Sleep Quality Index (PSQI) has been tested in a separate sample of 38 patients with PI undergoing CBT-I.

Results

RIS distinguishes well between controls and patients with PI. Internal consistency was within a good range (Cronbach alpha = .890). RIS was sensitive for detecting improvements after CBT-I in sleep parameters and target symptoms such as sleep-related thinking.

Conclusion

The RIS is a valid and feasible instrument for assessing psychological PI-symptoms and sleep parameters.

[Portable sleep monitoring in patients with disorders in falling asleep or maintaining sleep]

BACKGROUND

The most common diagnoses in sleep medicine are insomnia, sleep disordered breathing (SDB) and periodic leg movements (PLM). These disorders may coincide. This study examined the role of portable sleep monitoring in the diagnostic process and which sleep medicine diagnoses are additionally found in patients with disorders of initiating and maintaining sleep.

METHODS

A total of 217 patients, including 103 men (47.5%) and 114 (52.5%) women aged 52.2 ± 13.6 years with disorders of initiating or maintaining sleep were included in the study. Patients with known SDB were excluded. Patients were investigated using a stepwise diagnostic procedure with clinical interviews, questionnaires, clinical examination and portable sleep recording with electromyography (EMG) of the tibialis anterior muscle to diagnose SDB and PLM.

RESULTS

Of the patients 125 (57.6%) were diagnosed with insomnia according to the International Classification of Sleep Disorders (ICSD) and 70 (56%) had no other sleep disorder. Out of the 217 patients SDB was found in 107 (49.3%) patients, PLM in 90 patients (41.5%) and in 78 patients (35.9%) restless legs syndrome (RLS) was diagnosed. Among the 125 patients with insomnia 44 patients had RLS/PLMD and 35 had SDB in addition whereas SDB and RLS/PLMD were found in 33 subjects. All 3 disorders insomnia, RLS/PLMD and SDB were found in 24 subjects.

CONCLUSIONS

Out of 217 patients with a complaint of non-restorative sleep only 125 were finally diagnosed with insomnia. As 25.3% of patients showed combinations of sleep disorders, 49.3% with SDB and 41.5% with RLS/PLMD portable monitoring with electromyography of the legs is recommended. The investigation with a portable sleep monitoring system including an EMG of the tibialis muscle is very useful in patients with insomnia in addition to a clinical interview and questionnaires.

The AASM Scoring Manual four years later

PURPOSE OF REVIEW

Review published studies and critiques which evaluate the impact and effects of the American Academy of Sleep Medicine (AASM) Sleep Scoring Manual in the four years since its publication.

FINDINGS

USING THE AASM MANUAL RULES TO SCORE SLEEP AND EVENTS IN A POLYSOMNOGRAM (PSG) RESULTS IN: (1) very large differences in apnea-hypopnea indexes (AHI) when using the recommended and alternative rule for scoring hypopneas in adults; (2) increases in NREM 1 and sleep stage shifts with compensatory decreases in NREM 2 in children and adults when following rule 5.C.b. for ending NREM 2 sleep; (3) increases in NREM 3 in adults scoring slow wave activity in the frontal EEG derivations; (4) improved interscorer reliability; and (5) successfully identified fragmented sleep in children with obstructive sleep apnea (OSA) from primary snorers or normal controls because they had more NREM 1 and stage shifts using rule 5.C.b. Criticism of the Manual most often cited: (1) two rules for scoring hypopneas; (2) alternative EEG montage cancellation effects; (3) scoring stages 3 and 4 as NREM 3; and (4) too few rules for scoring arousals and REM sleep without atonia.

SUMMARY

Four years have passed since the AASM Scoring Manual was published with far less criticism than those who developed it feared. The AASM Manual provides a foundation upon which we all can build rules and methods which identify the complexity of sleep and its disorders.

Assessing periodicity of periodic leg movements during sleep

BACKGROUND

Periodic leg movements (PLM) during sleep consist of involuntary periodic movements of the lower extremities. The debated functional relevance of PLM during sleep is based on correlation of clinical parameters with the PLM index (PLMI). However, periodicity in movements may not be reflected best by the PLMI. Here, an approach novel to the field of sleep research is used to reveal intrinsic periodicity in inter movement intervals (IMI) in patients with PLM.

METHODS

Three patient groups of 10 patients showing PLM with OSA (group 1), PLM without OSA or RLS (group 2) and PLM with RLS (group 3) are considered. Applying the "unfolding" procedure, a method developed in statistical physics, enhances or even reveals intrinsic periodicity of PLM. The degree of periodicity of PLM is assessed by fitting one-parameter distributions to the unfolded IMI distributions. Finally, it is investigated whether the shape of the IMI distributions allows to separate patients into different groups.

RESULTS

Despite applying the unfolding procedure, periodicity is neither homogeneous within nor considerably different between the three clinically defined groups. Data-driven clustering reveals more homogeneous and better separated clusters. However, they consist of patients with heterogeneous demographic data and comorbidities, including RLS and OSA.

CONCLUSIONS

The unfolding procedure may be necessary to enhance or reveal periodicity. Thus this method is proposed as a pre-processing step before analyzing PLM statistically. Data-driven clustering yields much more reasonable results when applied to the unfolded IMI distributions than to the original data. Despite this effort no correlation between the degree of periodicity and demographic data or comorbidities is found. However, there are indications that the nature of the periodicity might be determined by long-range interactions between LM of patients with PLM and OSA.