REM sleep without atonia and nocturnal body position in prediagnostic Parkinson's disease

Deep profiling of nocturnal hypokinesia in multiple system atrophy and its clinical implications

STUDY OBJECTIVES

Patients with multiple system atrophy (MSA) spend more time supine overnight. Assessing nocturnal hypokinesia (NH) in MSA via video polysomnography (VPSG) is limited in metrics and analysis depth. This study deconstructs NH by sleep-wake phases, develops new VPSG-based body transition parameters, and explores their utility in understanding NH's pathogenesis and therapeutic implications in MSA.

METHODS

We retrospectively reviewed VPSG data of 150 participants - 58 MSA, 42 obstructive sleep apnea (OSA), and 50 controls. We analyzed the proportion of sleep in each body position and corresponding apnea-hypopnea indices (AHIs). Additionally, we assessed sleep-wake phase-specific and composite body transition indices (BTIs) (intra-phase, sleep-to-wake, wake, and modified BTI). Body position statistics, BTIs, and supine-to-lateral AHI reduction were compared across the three groups.

RESULTS

The MSA group had a significantly higher rate of sleep-time-on-back (STOB) and a lower proportion of lateral sleep. They also showed a lower sleep-to-wake BT/BTI compared to control and OSA groups, with no differences in intra-phase and wake BT/BTI. Furthermore, both the MSA and OSA groups showed greater AHI reduction from lateral positioning compared to the control group, with no significant difference between the MSA and OSA groups.

CONCLUSION

The proposed BTIs may serve as valuable adjuncts to sleep-time-on-back (%) in assessing NH, potentially indicating arousal-to-movement-arc impairment. Furthermore, NH-targeted treatments may benefit sleep-disordered breathing in patients with MSA.

Isolated REM Sleep without Atonia Is Not Equivalent to REM Sleep Behavior Disorder in Early-Stage Parkinson's Disease

BACKGROUND

In early-stage Parkinson's disease (PD), rapid eye movement (REM) sleep behavior disorder (RBD) predicts poor cognitive and motor outcome. However, the baseline significance and disease evolution associated with isolated REM sleep without atonia (iRWA, ie, enhanced muscle tone during 8.7% of REM sleep, but no violent behavior) are not well understood.

OBJECTIVES

The objective is to determine whether iRWA was a mild form of RBD and progressed similarly over time.

METHODS

Participants with early PD (<4 years from medical diagnosis) were included from 2014 to 2021 in a longitudinal study. They underwent interviews and examinations in the motor, cognitive, autonomous, psychiatric, sensory, and sleep domains every year for 4 years along with a video polysomnography and magnetic resonance imaging examination of the locus coeruleus/subcoeruleus complex (LC/LsC) at baseline. The clinical characteristics were compared between groups with normal REM sleep, with iRWA and with RBD, at baseline and for 4 years.

RESULTS

Among 159 PD participants, 25% had RBD, 25% had iRWA, and 50% had normal REM sleep. At baseline, the non-motor symptoms were less prevalent and the LC/LsC signal intensity was more intense in participants with iRWA than with RBD. Over 4 years, participants with normal REM sleep and with iRWA had a similar cognitive and motor trajectory, whereas participants with RBD had greater cognitive and motor decline.

CONCLUSIONS

We demonstrated that iRWA is frequent in early PD, but is not a milder form of RBD. Both groups have distinct baseline characteristics and clinical trajectories. They should be distinguished in clinical routine and research protocols. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Quantification of REM sleep without atonia: A review of study methods and meta-analysis of their performance for the diagnosis of RBD

The present review focuses on REM sleep without atonia (RSWA) scoring methods. In consideration of the numerous papers published in the last decade, that used different methods for the quantification of RSWA, their systematic revision is an emerging need. We made a search using the PubMed, Embase, Scopus and Web of Science Databases, from 2010 until December 2021, combining the search term "RSWA" with "scoring methods", "IRBD", "alfasyn disease", and "neurodegenerative disease", and with each of the specific sleep disorders, diagnosed according to current criteria, with the identification of the references of interest for the topic. Furthermore, a Meta-analysis of the diagnostic performance of RSWA scoring methods, in terms of sensitivity and specificity, was carried out. The comparison of the hierarchical summary receiver-operating characteristic curves obtained for visual methods and that obtained for the automated REM sleep atonia index (RAI), shows substantially similar prediction areas indicating a comparable performance. This systematic review and meta-analysis support the validity of a series of visual methods and of the automated RAI in the quantification of RSWA with the purpose to guide clinicians in the interpretation of their results and their correct and efficient use within the diagnostic work-up for REM sleep behavior disorder.

Polysomnographic Predictors of Sleep, Motor, and Cognitive Dysfunction Progression in Parkinson's Disease

PURPOSE OF REVIEW

Sleep disturbances are an important nonmotor feature of Parkinson's disease (PD) that can cause polysomnographic (PSG) alterations. These alterations are already present in early PD and may be associated with a specific disease course. This systematic review describes the role of PSG variables as predictors of sleep dysfunction, motor and cognitive dysfunction progression in PD.

RECENT FINDINGS

Nineteen longitudinal cohort studies were included. Their main findings were that (1) REM sleep behavioral events, REM sleep without atonia (RSWA), and electroencephalography (EEG) changes (mainly microsleep instability) are predictors of the development of REM sleep behavior disorder (RBD); (2) RBD, RSWA, and lower slow-wave sleep energy predict motor progression; (3) RBD, EEG slowing, and sleep spindles changes are predictors of cognitive deterioration; and (4) OSA is associated with severe motor and cognitive symptoms at baseline, with inconsistent findings on the effect of continuous positive airway pressure (CPAP) therapy for these symptoms. The results of our systematic review support a role of the video-PSG in disease progression prediction in PD and its usefulness as a biomarker. However, future studies are needed to investigate whether treatment of these PSG abnormalities and sleep disturbances may have a neuroprotective effect on disease progression.

Impaired bed mobility in prediagnostic and de novo Parkinson's disease

BACKGROUND

Wearable technology research suggests that nocturnal movements are disturbed in early Parkinson's disease (PD). In this study, we investigate if patients also already experience impaired bed mobility before PD diagnosis. Furthermore, we explore its association with motor and nonmotor features and its value for phenoconversion and disease progression prediction.

METHODS

PPMI data were downloaded for de novo PD subjects, subjects at-risk for developing a synucleinopathy (with isolated REM sleep behavior disorder, hyposmia or a pathogenic genetic variant) and controls. Impaired bed mobility was assessed with the MDS-UPDRS part 2 item 9. A frequency analysis was performed. Multivariable logistic regression analyses were used to investigate the association with other PD variables. Cox proportional-hazards models were used to test if difficulties with turning in bed could predict phenoconversion. Linear mixed models were used to evaluate if difficulties with turning in bed could predict disease progression.

RESULTS

Of the at-risk subjects, 9.2-12.5% experienced difficulties with turning in bed vs. 25.0% of de novo PD subjects and 2.5% of controls. Impaired turning ability was associated with MDS-UPDRS motorscore (axial signs in the at-risk group, bradykinesia in the de novo PD group) and SCOPA-AUT score (gastrointestinal symptoms). In addition, difficulties with turning in bed were a significant predictor for phenoconversion in the at-risk group and for development of motor complications in the de novo PD group.

CONCLUSION

Our findings suggest that difficulties with turning in bed can be helpful as clinical symptom for a prodromal PD screening and for motor complication prediction in early PD.