Autonomic dysfunction in isolated rapid eye movement sleep without atonia

Automatic analysis of muscular activity in the flexor digitorum superficialis muscles: a fast screening method for rapid eye movement sleep without atonia

STUDY OBJECTIVES

To identify a fast and reliable method for rapid eye movement (REM) sleep without atonia (RWA) quantification.

METHODS

We analyzed 36 video-polysomnographies (v-PSGs) of isolated REM sleep behavior disorder (iRBD) patients and 35 controls' v-PSGs. Patients diagnosed with RBD had: i) RWA, quantified with a reference method, i.e. automatic and artifact-corrected 3-s Sleep Innsbruck Barcelona (SINBAR) index in REM sleep periods (RSPs, i.e. manually selected portions of REM sleep); and ii) v-PSG-documented RBD behaviors. We quantified RWA with other (semi)-automated methods requiring less human intervention than the reference one: the indices proposed by the SINBAR group (the 3-s and 30-s phasic flexor digitorum superficialis (FDS), phasic/"any"/tonic mentalis), and the REM atonia, short and long muscle activity indices (in mentalis/submentalis/FDS muscles). They were calculated in whole REM sleep (i.e. REM sleep scored following international guidelines), in RSPs, with and without manual artifact correction. Area under curves (AUC) discriminating iRBD from controls were computed. Using published cut-offs, the indices' sensitivity and specificity for iRBD identification were calculated. Apnea-hypopnea index in REM sleep (AHIREM) was considered in the analyses.

RESULTS

RWA indices from FDS muscles alone had the highest AUCs and all of them had 100% sensitivity. Without manual RSP selection and artifact correction, the "30-s phasic FDS" and the "FDS long muscle activity" had the highest specificity (85%) with AHIREM < 15/h. RWA indices were less reliable when AHIREM≥15/h.

CONCLUSIONS

If AHIREM<15/h, FDS muscular activity in whole REM sleep and without artifact correction is fast and reliable to rule out RWA.

Treatment with the novel TAAR1 agonist ulotaront is associated with reductions in quantitative polysomnographic REM sleep without atonia in healthy human subjects: Results of a post-hoc analysis

BACKGROUND

Isolated REM sleep behavior disorder (RBD) is a potentially injurious parasomnia lacking an established treatment. Ulotaront is a trace amine-associated receptor 1 (TAAR1) agonist with 5-HT_1A receptor agonist activity that has demonstrated efficacy in patients with schizophrenia. In a single dose challenge study in humans, ulotaront 50 mg demonstrated significant REM suppressant effects. We now report post-hoc exploratory analyses designed to evaluate the effect of ulotaront on quantitative REM sleep without atonia (RSWA).

METHODS

Young healthy adult men (ages 19-35) were randomized to double-blind, cross-over treatment (after 7-day wash-out) with single doses of ulotaront (50 mg or 10 mg) versus placebo followed by polysomnography (PSG) on each of the nights following treatment. Quantitative RSWA was analyzed in a blinded fashion using established visual and automated methods.

RESULTS

Subjects received 50 mg (n = 11) or 10 mg (n = 9) of ulotaront. Treatment with ulotaront 50 mg was associated with lower RSWA (p < 0.05), with greatest RSWA reduction (vs. placebo) observed in subjects with RSWA levels above the mean on the baseline night. RSWA levels were similar between treatment with ulotaront 10 mg and placebo.

CONCLUSION

Treatment with ulotaront 50 mg (but not 10 mg) was associated with reductions in RSWA levels in healthy subjects, especially in subjects with higher baseline RSWA levels, providing proof-of-concept for ulotaront efficacy in reducing RSWA levels. However, whether ulotaront might have efficacy as a treatment for human RBD awaits double-blind trials with ulotaront in clinical RBD populations.

Predictors of RBD progression and conversion to synucleinopathies

Purpose of review

Rapid eye movement (REM) sleep behaviour disorder (RBD) is considered the expression of the initial neurodegenerative process underlying synucleinopathies and constitutes the most important marker of their prodromal phase. This article reviews recent research from longitudinal research studies in isolated RBD (iRBD) aiming to describe the most promising progression biomarkers of iRBD and to delineate the current knowledge on the level of prediction of future outcome in iRBD patients at diagnosis.

Recent findings

Longitudinal studies revealed the potential value of a variety of biomarkers, including clinical markers of motor, autonomic, cognitive, and olfactory symptoms, neurophysiological markers such as REM sleep without atonia and electroencephalography, genetic and epigenetic markers, cerebrospinal fluid and serum markers, and neuroimaging markers to track the progression and predict phenoconversion. To-date the most promising neuroimaging biomarker in iRBD to aid the prediction of phenoconversion is striatal presynaptic striatal dopaminergic dysfunction.

Summary

There is a variety of potential biomarkers for monitoring disease progression and predicting iRBD conversion into synucleinopathies. A combined multimodal biomarker model could offer a more sensitive and specific tool. Further longitudinal studies are warranted to iRBD as a high-risk population for early neuroprotective interventions and disease-modifying therapies.

Associations between sleep bruxism and other sleep-related disorders in adults: a systematic review

OBJECTIVE

Systematic reviews on sleep bruxism (SB) as a comorbid condition of other sleep-related disorders are lacking. Such reviews would contribute to the insight of sleep clinicians into the occurrence of SB in patients with other sleep-related disorders, and into the underlying mechanisms of such comorbid associations. This systematic review aimed: 1. to determine the prevalence of SB in adults with other sleep-related disorders; and 2. to determine the associations between SB and other sleep-related disorders, and to explain the underlying mechanisms of these associations.

METHODS

A systematic search on SB and sleep-related disorders was performed in PubMed, Embase, Cochrane Library, and Web of Science to identify eligible studies published until May 15, 2020. Quality assessment was performed using the Risk of Bias Assessment tool for Non-randomized Studies.

RESULTS

Of the 1539 unique retrieved studies, 37 articles were included in this systematic review. The prevalence of SB in adult patients with obstructive sleep apnea, restless leg syndrome, periodic limb movement during sleep, sleep-related gastroesophageal reflux disease, REM behavior disorder (RBD), and sleep-related epilepsy was higher than that in the general population. The specific mechanisms behind these positive associations could not be identified.

CONCLUSIONS

SB is more prevalent in patients with the previously mentioned disorders than in the general population. Sleep arousal may be a common factor with which all the identified disorders are associated, except RBD and Parkinson's disease. The associations between SB and these identified sleep-related disorders call for more SB screening in patients with the abovementioned sleep-related disorders.

Twenty-four hour blood pressure profile in idiopathic REM sleep behaviour disorder

STUDY OBJECTIVES

To determine whether autonomic dysfunction in idiopathic REM sleep behaviour disorder (iRBD) affects circadian blood pressure (BP) profile.

METHODS

21 iRBD (mean age 68.8±6.4, mean age at onset 62.2±9.3), 21 drug-free de novo Parkinson's disease (PD) subjects and 21 control subjects (HCs), comparable for age and sex, underwent 24-hour ambulatory BP monitoring. A prospective follow-up study was performed to evaluate the occurrence of neurodegenerative disorders in the iRBD cohort.

RESULTS

In the iRBD group, night-time systolic BP (SBP) was higher (124.0±20.0, p=.026), nocturnal BP decrease lower (4.0±8.7% for SBP and 8.7±8.0% for DBP, p=.001), and non-dipping status more frequent (71.4% for systolic and 52.4% for diastolic BP; p=.001 and p=.01 respectively) than in the HCs. Reverse dipping of SBP was found in 23.8% (p=.048) of the iRBD subjects. Non-dipping status was not associated with differences in gender, age, disease duration, age at disease onset, UPDRS score, presence of antihypertensive therapy or polysomnographic measures. Patients with PD showed daytime and night-time BP profiles comparable to those observed in iRBD. A sub-group analysis considering only the subjects without antihypertensive therapy (12 iRBD, 12 PD) showed results superimposable on those of the whole iRBD and PD groups.Longitudinal follow up (mean 5.1±1.9 years) showed no differences in BP profile at baseline between converters (n=6) and non-converters.

CONCLUSIONS

24-hour BP control was impaired in iRBD. This impairment, similar to patterns observed in de novo PD, consisted of reduced amplitude of nocturnal dipping and increased frequency of non-dipping status. These findings could have implications for cardiovascular morbidity and mortality in iRBD.

Flexor digitorum superficialis muscular activity is more reliable than mentalis muscular activity for rapid eye movement sleep without atonia quantification

STUDY OBJECTIVES

To evaluate interrater reliability for artefact correction in the context of semi-automated quantification of rapid eye movement (REM) sleep without atonia (RWA) in the mentalis and flexor digitorum superficialis (FDS) muscles.

METHODS

We included video-polysomnographies of 14 subjects with apnea-hypopnea-index in REM sleep (AHIREM)<15/h and 11 subjects with AHIREM≥15/h. Eight subjects had isolated REM sleep behavior disorder. A validated algorithm (www.osg.be) automatically scored phasic and "any" EMG activity in the mentalis muscle, and phasic EMG activity in the FDS muscles. Four independent expert scorers performed artefact correction according to the SINBAR (Sleep Innsbruck Barcelona) recommendations. Interrater reliability for artefact correction was computed with B-statistics. The variability across scorers of four RWA indices (phasic mentalis, "any" mentalis, phasic FDS and SINBAR - i.e. "any" mentalis and/or phasic FDS - EMG activity indices) was computed. With Friedman tests we compared B-statistics obtained for mentalis and FDS muscles, and the variability of the RWA indices. Influence of AHIREM and RBD diagnosis on the RWA indices variability was evaluated with linear regressions.

RESULTS

Interrater reliability for artefact correction was higher in the FDS than in the mentalis muscle (p<0.001). Phasic FDS activity was minimally affected by artefacts. Accordingly, the phasic FDS EMG activity index had the lowest variability across scorers (p<0.001). Variability across scorers of the RWA indices including the mentalis muscle increased with AHIREM and was independent from RBD diagnosis.

CONCLUSIONS

Due to the consistently found low number of artefacts, phasic FDS activity is a reliable measure of RWA.

Association of heart rate variability with REM sleep without atonia in idiopathic REM sleep behavior disorder

STUDY OBJECTIVES

Idiopathic rapid eye movement sleep behavior disorder (iRBD), characterized by rapid eye movement sleep without atonia (RSWA) and dream-enactment behavior, has been suggested to be a predictor of α-synucleinopathies. Autonomic instability, represented by heart rate variability, is a common characteristic of both iRBD and α-synucleinopathies. Previous studies reported that RSWA was associated with autonomic dysfunction and was a possible predictor of phenoconversion. Therefore, we sought to compare heart rate variability between iRBD and control groups and explore the relationship between heart rate variability and RSWA in patients with iRBD.

METHODS

Nocturnal polysomnographic data on 47 patients (28 men, 19 women) diagnosed with iRBD based on video-polysomnography and 26 age-matched and sex-matched controls were reviewed. The first 5-minute epoch with a stable electrocardiogram lead II on video-polysomnography was selected from stage N2, wake, and rapid eye movement. For quantification of RSWA, tonic activity was analyzed from the submentalis electromyogram and phasic activity from the submentalis and bilateral anterior tibialis electromyogram channels.

RESULTS

Compared to the control group, the iRBD group showed significant reductions in the standard deviation of the R-R intervals, the root mean square of successive R-R interval differences, and high-frequency values. Quantified tonic activity was inversely correlated with normalized low-frequency values and low-frequency/high-frequency ratios and positively correlated with normalized high-frequency values.

CONCLUSIONS

This study implied decreased cardiac autonomic function in patients with iRBD, which showed parasympathetic predominance. Heart rate variability of the patients with iRBD in this study was associated with quantified tonic RSWA, which was previously reported to be a possible predictor of phenoconversion.

Self-Reported Rapid Eye Movement Sleep Behavior Disturbance and Its Associated Factors among Medicine and Health Science Students at the University of Gondar

Introduction

Rapid eye movement sleep behavior disorder (RBD) is characterized by dream-enacting behavior (shouting, punching, and falling out of bed) related to unpleasant dreams and loss of normal rapid eye movement (REM) sleep muscle atonia. Rapid eye movement sleep enhances learning and memory by regulating neuronal synapses, and if it is undesirable, it can lead to cognitive impairment and poor academic performance and may end up with death. To the best of our searching databases, there is no such study conducted in Ethiopia. Therefore, this study is aimed at determining self-reported symptoms of RBD and its associated factors among the University of Gondar medicine and health science students (2019).

Methods

We conducted a cross-sectional study from June 1 to July 2019, among medicine and health science students at the University of Gondar using a simple random sampling technique. A self-reported RBD screening questionnaire was used to collect the data. We used Epi Info™ 7.0.8.3 and Stata 14 for data entry and statistical analyses, respectively. Descriptive statistics (frequency with percent and mean with standard deviation) and adjusted odds ratio (AOR) with 95% uncertainty interval (UI) were computed. In a multivariable binary logistic regression, variables with a p < 0.05 were declared as significant.

Results

Three hundred and eighty-seven students took part in the study. The mean age of participants was 20.81 (±1.83) years. The prevalence of self-reported RBD was 46.25% [95% UI (41.26%-51.24)]. Physical exercise immediately before sleep (AOR = 2.50, 95% UI (1.24-5.02)), using Facebook immediately before sleep (AOR = 1.93, 95% UI (1.18-3.15)), having daytime sleepiness (AOR = 1.92, 95% UI (1.16-3.19)), and self-reported depressive symptoms (AOR = 2.40, 95% UI (1.45-3.99)) were significantly associated with self-reported RBD.

Conclusion

The current study revealed a high prevalence of self-reported RBD. This remarkable problem suggested a need to design strategies to prevent RBD symptoms among university students through targeting screening of depression, daytime sleepiness, and adjusting bedtime routines such as physical exercise and internet use immediately before going to bed.

Rapid eye movement sleep behavior disorder and the link to alpha-synucleinopathies

Rapid eye movement (REM) sleep behavior disorder (RBD) involves REM sleep without atonia in conjunction with a recurrent nocturnal dream enactment behavior, with vocalizations such as shouting and screaming, and motor behaviors such as punching and kicking. Secondary RBD is well described in association with neurological disorders including Parkinson's disease (PD), multiple system atrophy (MSA), and other conditions involving brainstem structures such as tumors. However, RBD alone is now considered to be a potential harbinger of later development of neurodegenerative disorders, in particular PD, MSA, dementia with Lewy bodies (DLB), and pure autonomic failure. These conditions are linked by their underpinning pathology of alpha-synuclein protein aggregation. In RBD, it is therefore important to recognize the potential risk for later development of an alpha-synucleinopathy, and to investigate for other potential causes such as medications. Other signs and symptoms have been described in RBD, such as orthostatic hypotension, or depression. While it is important to recognize these features to improve patient management, they may ultimately provide clinical clues that will lead to risk stratification for phenoconversion. A critical need is to improve our ability to counsel patients, particularly with regard to prognosis. The ability to identify who, of those with RBD, is at high risk for later neurodegenerative disorders will be paramount, and would in addition advance our understanding of the prodromal stages of the alpha-synucleinopathies. Moreover, recognition of at-risk individuals for neurodegenerative disorders may ultimately provide a platform for the testing of possible neuroprotective agents for these neurodegenerative disorders.

REM sleep behavior disorder, autonomic dysfunction and synuclein-related neurodegeneration: where do we stand?

INTRODUCTION

From newfound parasomnia to a marker of future synucleinopathy, since its first description in 1986, REM sleep behavior disorder (RBD) has been systematically tackled from virtually many viewpoints in basic, translational, and clinical studies. The time delay between RBD and synucleinopathy onset offers an exceptional window for observation and design of neuroprotective trials. In the last few years, research has focused on characterizing possible differences within RBD patients in order to draw potential profiles more or less susceptible to further neurodegeneration. Attention has been drawn towards autonomic dysfunction in RBD as one of such variables.

OVERVIEW

In this review, REM sleep physiology and relevant brain anatomy is briefly mentioned and integrated with neuroanatomical and physiological concepts regarding the central autonomic network. A detailed summary of works showing the presence of autonomic dysfunction in RBD is provided, and clinical and electrophysiological features of RBD in synucleinopathies are discussed. A short overview of RBD in other neurodegenerative diseases is also provided.