The relation between abnormal behaviors and REM sleep microstructure in patients with REM sleep behavior disorder

ObjectiveTo investigate the temporal relation between rapid eye movement (REM) sleep microstructure (REMs, EMG activity) and motor events in REM sleep behavior disorder (RBD).MethodsPolysomnographic records of eight patients with RBD were analyzed and compared with those of eight sex- and age-matched controls. We examined sleep microstructure for REM sleep with and without REMs and phasic chin EMG activity and their temporal relation to motor events on video.ResultsAll types of motor events were either more frequent in RBD patients than in controls (P ? 0.007) or present solely in RBD patients. In RBD, major motor events were significantly more frequent during REM sleep with REMs than during REM sleep without REMs (violent, 84.0% vs. 16.0%, P < 0.001; complex/scenic behavior, 78.1% vs. 23.2%, P < 0.001; major jerks, 77.5% vs. 20.3%, P < 0.001), whereas minor motor activity was evenly distributed (54.1% vs. 45.9%, P = 0.889). Controls showed predominantly minor motor activity with rare myoclonic body jerks. The distribution of motor events did not differ between REM sleep with and without REMs (40.9% vs. 59.1%, P = 0.262).ConclusionsIn RBD, major motor activity is closely associated with REM sleep with REMs, whereas minor jerks occur throughout REM sleep. This finding further supports the concept of a dual nature of REM sleep with REMs and REM sleep without REMs and implies a potential gate control mechanism of REM sleep with REMs for the manifestation of elaborate or violent behaviors in RBD.     

Surface EMG activity during REM sleep in Parkinson's disease correlates with disease severity

ObjectivesOver 40% of individuals with Parkinson's disease (PD) have rapid eye movement sleep behavior disorder (RBD). This is associated with excessive sustained (tonic) or intermittent (phasic) muscle activity instead of the muscle atonia normally seen during REM sleep. We examined characteristics of manually-quantitated surface EMG activity in PD to ascertain whether the extent of muscle activity during REM sleep is associated with specific clinical features and measures of disease severity.MethodsIn a convenience sample of outpatients with idiopathic PD, REM sleep behavior disorder was diagnosed based on clinical history and polysomnogram, and severity was measured using the RBD sleep questionnaire. Surface EMG activity in the mentalis, extensor muscle group of the forearms, and anterior tibialis was manually quantitated. Percentage of REM time with excessive tonic or phasic muscle activity was calculated and compared across PD and RBD characteristics.ResultsAmong 65 patients, 31 had confirmed RBD. In univariate analyses, higher amounts of surface EMG activity were associated with longer PD disease duration (srho = 0.34; p = 0.006) and greater disease severity (p < 0.001). In a multivariate regression model, surface EMG activity was significantly associated with RBD severity (p < 0.001) after adjustment for age, PD disease duration, PD severity and co-morbid sleep abnormalities.ConclusionSurface EMG activity during REM sleep was associated with severity of both PD and RBD. This measure may be useful as a PD biomarker and, if confirmed, may aid in determining which PD patients warrant treatment for their dream enactment to reduce risk of injury.     

Quantitative assessment of isolated rapid eye movement (REM) sleep without atonia without clinical REM sleep behavior disorder: clinical and research implications

BackgroundRapid eye movement (REM) sleep without atonia (RWA) is observed in some patients without a clinical history of REM sleep behavior disorder (RBD). It remains unknown whether these patients meet the refined quantitative electromyographic (EMG) criteria supporting a clinical RBD diagnosis. We quantitatively evaluated EMG activity and investigated its overnight distribution in patients with isolated qualitative RWA.MethodsFifty participants with an incidental polysomnographic finding of RWA (isolated qualitative RWA) were included. Tonic, phasic, and ‘any’ EMG activity during REM sleep on PSG were quantified retrospectively.ResultsReferring to the quantitative cut-off values for a polysomnographic diagnosis of RBD, 7/50 (14%) and 6/50 (12%) of the patients showed phasic and ‘any’ EMG activity in the mentalis muscle above the respective cut-off values. No patient was above the cut-off value for tonic EMG activity or phasic EMG activity in the anterior tibialis muscles. Patients with RWA above the cut-off value showed higher amounts of RWA during later REM sleep periods.ConclusionsThis is the first study showing that some subjects with incidental RWA meet the refined quantitative EMG criteria for a diagnosis of RBD. Future longitudinal studies must investigate whether this subgroup with isolated qualitative RWA is at an increased risk of developing fully expressed RBD and/or neurodegenerative disease.     

Polysomnographic diagnosis of idiopathic REM sleep behavior disorder

The presence of either excessive tonic chin EMG activity during REM sleep, or excessive phasic submental or limb EMG twitching is required to diagnose REM sleep behavior disorder (RBD). The aim was to identify cut‐off values and to assess the sensitivity and specificity of these values taken separately or combined to diagnose idiopathic RBD patients. Eighty patients presenting with a clinical diagnosis of idiopathic RBD and 80 age‐ and gender‐matched normal controls were studied in the sleep laboratory. Receiver operating characteristic curves were drawn to find optimal cut‐off values for three REM sleep EMG parameters. Tonic and phasic EMG activity were measured in the chin, but not in the limbs. Videos were examined during the recording but were not systematically reviewed by the authors. Total correct classification of 81.9% was found for tonic chin EMG density ≥30%; 83.8% for phasic chin EMG density ≥15% and 75.6% for ≥24 leg movements per hour of REM sleep. Five patients did not fulfill any of these three polysomnographic (PSG) criteria. Conversely, one subject of the control group met the PSG criteria for RBD. This study estimates the diagnostic value of a visual scoring method for the diagnosis of idiopathic RBD and establishes cut‐off values to be used in clinical and research set‐ups. For the five RBD patients who did not show chin EMG abnormalities, it cannot be excluded that they had increased phasic EMG activity in the upper limbs and presented visible motor activity. © 2010 Movement Disorder Society     

Two polysomnographic features of REM sleep behavior disorder: Clinical variations insight for Parkinson's disease

IntroductionLoss of REM sleep muscle atonia (RWA) and dream-enactment behavior (DEB) are two associated features of REM sleep behavior disorder (RBD), which is frequently associated with Parkinson's disease (PD). Few studies have examined both DEB and RWA simultaneously in patients with PD. This study aimed to evaluate relationships between RWA, DEB and clinical characteristics of PD.MethodsWe conducted overnight polysomnography in 145 patients with PD. DEB (motor behaviors and/or vocalizations during REM) and increased RWA (IRWA; tonic and phasic chin EMG density ≥ 30% and ≥15%, respectively) were identified. Patients were categorized as clinical RBD (DEB and IRWA), sub-DEB positive (DEB only), subclinical RBD (IRWA only), or normal REM sleep.ResultsPatients with DEB had higher Hoehn and Yahr (H&Y) stage, Unified Parkinson's Disease Rating Scale (UPDRS) III score, levodopa equivalent dose(LEDs), and worse cognition. RWA was associated with H&Y stage, LEDs, cognition, and sleep structure in all patients. PD duration was associated with RWA, but not DEB. The PD patients who exhibited clinical or subclinical RBD, compared to sub-DEB positive, had higher H&Y stage, UPDRS III score and LEDs, lower cognitive score, worse sleep structure than the PD + cREM group.ConclusionBoth DEB and RWA were associated with severity of PD illness. Subclinical RBD might have different disease progression from sub-DEB positive. DEB symptoms may fluctuate or disappear whereas RWA may continue to develop as PD progresses. Differences in the course of DEB and RWA may reflect the difference in the degeneration process of neurodegenerative disorders.     

Impaired decision-making in idiopathic REM sleep behavior disorder

BackgroundPatients with REM sleep behavior disorder (RBD) frequently develop Parkinson’s disease (PD), which can impair decision-making ability. This study was undertaken to investigate decision-making ability and its relation to olfactory function in patients with idiopathic RBD.MethodsThis study used the Iowa Gambling Task (IGT) and the Sniffin’ Stick Test for examination of 38 patients with idiopathic RBD (iRBD) and 34 age-matched healthy control subjects (HC). Associations between these test results and other clinical RBD variables were also assessed.ResultsTotal IGT score and Sniffin’ Stick Test scores were significantly lower in the iRBD group than in the HC group. The iRBD group IGT scores in the first, third, and final blocks were significantly lower than those of the HC group. In the iRBD group, no association was found between the total IGT score and the Sniffin’ Stick Test score or any clinical RBD variable.ConclusionsImpaired decision-making associated with iRBD can herald PD. However, decision-making disability is thought to appear irrespective of olfactory dysfunction and progression of RBD pathology.     

Observations on muscle activity in REM sleep behavior disorder assessed with a semi-automated scoring algorithm

Objectives

Rapid eye movement (REM) sleep behavior disorder (RBD) is defined by dream enactment due to a failure of normal muscle atonia. Visual assessment of this muscle activity is time consuming and rater-dependent.

The role of pedunculopontine nucleus in isolated REM sleep behavior disorder and REM sleep without atonia

IntroductionThe aim of this study was to analyze the functions of pedunculopontine nucleus (PPN) in isolated REM sleep behavior disorder (iRBD) and REM sleep without atonia (RSWA) to investigate the role of PPN in dream-enacting motor behaviors in RBD. We evaluated the activity of PPN through the prepulse modulation (PPM) together with other brainstem reflexes to investigate the differences in changes at brainstem.MethodsWe included nine patients with isolated RSWA and 10 patients with iRBD. For diagnosis, all patients underwent polysomnography. None of the patients had parkinsonism or dementia. We also included 17 healthy participants with similar age and sex. Blink reflex (BR), PPM of BR, recovery excitability of BR, and auditory startle reflex (ASR) were recorded in all participants.ResultsThere was a prepulse inhibition deficit in iRBD and RSWA groups compared to healthy subjects. The BR-R2 recovery at 200 ms interval was also higher in patients with iRBD and RSWA. In ASR recordings, the response probabilities were higher in the RBD group compared to RSWA and control groups.ConclusionThe PPM was abnormal in both iRBD and RSWA whereas ASR was enhanced in iRBD. We suggest that there are certain similarities and differences in the pathophysiologies of iRBD and RSWA.     

Decreased phasic EMG activity during rapid eye movement sleep in treatment‐naïve Parkinson's disease: Effects of treatment with levodopa and progression of illness

Rapid eye movement (REM) sleep behavior disorder (RBD) is frequently associated with Parkinson's disease (PD) and may anticipate its diagnosis by several years. We assessed the presence of motor dyscontrol during REM sleep in treatment‐naïve PD patients and investigated the putative effect of levodopa (L ‐dopa) treatment on motor activity. Overnight sleep studies were performed on 15 previously untreated PD patients and 14 controls at baseline, again after a 3‐ to 9‐month treatment period with a low dose of L ‐dopa, and 2 to 5 days after treatment discontinuation (in 8 patients). No differences in sleep parameters were observed across groups or treatment conditions. None of the patients met criteria for RBD at baseline, whereas 5 patients were symptomatic at the time of the second sleep study. A quantitative analysis of electromyographic (EMG) activity during REM sleep showed a lower phasic twitching activity in untreated PD than in controls. However, an increase in both phasic twitching and tonic activity was found after treatment with L ‐dopa. Discontinuation of treatment resulted in a return to pretreatment values of phasic but not of tonic EMG activity. Thus, the increase in phasic activity seems to depend on the effects of L ‐dopa, whereas the increase in tonic EMG activity during REM sleep might be caused by other factors such as the progression of disease. Potential implications for the understanding of the relationship between RBD and PD are discussed. © 2002 Movement Disorder Society     

A preliminary quantitative analysis of REM sleep chin EMG in Parkinson's disease with or without REM sleep behavior disorder

ObjectivesTo compare REM sleep chin EMG quantitative features between Parkinson’s disease (PD) patients with or without REM sleep behavior disorder (RBD).Subjects and methodsTwenty-seven consecutive PD patients (mean age 67.9 years) and 19 normal controls (mean age 67.5 years) were enrolled. Detailed clinical, laboratory, and polysomnographic studies were obtained in all participants and characteristics of chin electromyographic amplitude during rapid eye movements sleep were analyzed by means of an automatic quantitative approach (Atonia Index).ResultsSixteen of the 27 patients were affected by RBD. An Atonia Index below 0.90 showed high sensitivity (0.938) and specificity (0.909) for the diagnosis of RBD within the group of PD patients.ConclusionThis study recommends the Atonia Index as an objective measure to support and aid the diagnosis of RBD in PD.     

The implication of nigrostriatal dopaminergic degeneration in the pathogenesis of REM sleep behavior disorder

Background and purpose: The pathogenesis of rapid eye movement (REM) sleep behavior disorder (RBD) is not clear despite its frequent association with Parkinson’s disease (PD). We investigated whether the nigrostriatal dopaminergic system is involved in the development of idiopathic RBD. Methods: Fourteen patients with RBD, 14 patients with PD and 12 normal controls were included in the study. The diagnosis of RBD was confirmed on polysomnography. All the participants performed single‐photon emission computed tomography imaging 3 h after injection of [¹²³I]FP‐CIT. During REM sleep of the RBD patients, each 30‐s epoch was rated as ‘tonic’ when there was at least 50% of tonically maintained chin electromyography (EMG) activity in the epoch. Phasic EMG activities were calculated as the percentage of 3‐s mini‐epoch containing phasic EMG events (leg and chin, separately). Results: The RBD patients showed a trend of lower binding in the striatum than the normal controls (P = 0.07), and the significance was revealed in the putamen (P = 0.02). However, in 11 individual cases of the 14 RBD patients, the dopamine transporter (DAT) densities in the putamen still remained within the normal range. In the RBD patients, there was no correlation between EMG activities and DAT densities. Conclusions: Nigrostriatal dopaminergic degeneration could be a part of the pathogenesis of RBD, but not essential for the development of RBD. The lack of correlation between RBD severity and DAT densities suggests that another pathogenic process not related to nigrostriatal dopaminergic transmission may be implicated in RBD.     

Polysomnographic features of REM sleep behavior disorder: development of a scoring method.

REM sleep behavior disorder (RBD) is characterized by the intermittent absence of REM sleep EMG atonia and the appearance of elaborate motor activity associated with dream mentation. There are no specific diagnostic criteria for RBD based upon polysomnographic findings. We describe a new scoring method and show its sensitivity to treatment with clonazepam. An increased phasic submental EMG density occurs in RBD patients, but REM density is similar to that of controls. Clonazepam selectively decreases REM sleep phasic activity but exerts no effect on REM sleep atonia. Periodic limb movements in sleep (PLMS) occur equally in both REM and NREM sleep in RBD patients, suggesting that normal suppression of PLMS in REM sleep is due to motor inhibition.     

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

BackgroundSleep disturbances are features of Parkinson's disease (PD), that can already occur before PD diagnosis. The most investigated prodromal PD sleep disorder is REM sleep behavior disorder (RBD). The relation between other polysomnographic (PSG) alterations and the prediagnostic stages of PD, however, is less clear.MethodsWe performed a retrospective case–control study to characterize polysomnographic alterations in PD and prediagnostic PD. We included 63 PD subjects (33 subjects that underwent a video-PSG before PD diagnosis [13 with and 20 without RBD] and 30 subjects that underwent a PSG after PD diagnosis) and 30 controls. PSGs were analyzed for sleep stages, different RSWA variables, body position, arousals, periodic limb movements, and REM density.ResultsHigher subscores of all RSWA variables were observed in subjects with PD and prediagnostic PD (with and without RBD). Total RSWA, tonic RSWA and chin RSWA severity were significant predictors for all PD and prediagnostic PD groups. Our study also shows a higher percentage of nocturnal supine body position in all PD and prediagnostic PD groups. Supine body position percentage is the highest in the PD group and has a positive correlation with time since diagnosis.ConclusionsThese findings suggest that increased total, tonic and chin RSWA as well as nocturnal supine body position are already present in prediagnostic PD, independently of RBD status. Prospective longitudinal studies are necessary to confirm the additional value of these PSG abnormalities as prodromal PD biomarkers.     

Gender differences in clinical findings and α-synucleiopathy-related markers in patients with idiopathic REM sleep behavior disorder

BackgroundRapid eye movement (REM) sleep behavior disorder (RBD) is a male-predominant parasomnia. Earlier clinical RBD patient studies showed gender differences of clinical symptoms and polysomnographic (PSG) findings. However, no previous investigated this issue by means of validated severity scales or by neuropsychological examination related to alpha-synucleinopathy. This study elucidates gender differences in clinical, physiological, and neuropsychological findings in Japanese idiopathic RBD (iRBD) patients.MethodsFrom 220 patients with complaint of sleep-related vocalization or behaviors who visited Yoyogi Sleep Disorder Center from June 2003 through December 2016, 43 female (68.7 ± 7.3 yr) and 141 male patients (66.7 ± 6.7 yr) diagnosed as having iRBD by video-polysomnography (v-PSG) were selected. All subjects answered the RBD questionnaire (RBDQ-JP) and underwent olfactory function test (Sniffin' Sticks test) and cognitive function test (MoCA-J).ResultsFemale iRBD patients had later first symptom-witnessed age (sleep-talking 63.2 ± 10.5 yr, behaviors 60.9 ± 8.6 yr) than male patients (sleep-talking 59.1 ± 8.8 yr, behaviors 64.7 ± 8.9 yr). No gender difference was found in age at diagnosis, clinical severity (RBDQ-JP), or olfactory or cognitive function. Regarding electromyogram (EMG) findings during REM sleep, phasic EMG activity was higher in female patients (22.3 ± 17.8% vs. 16.5 ± 16.1%), although no difference was found in tonic EMG activity.ConclusionsAlthough female iRBD patient symptoms were first recognized later than those of male patients, they showed elevated EMG activity during REM sleep and showed deteriorated olfactory and cognitive function similarly to male patients at the first medical consultation. Results suggest that disease progression in female RBD patients is equivalent to that in male patients.     

Factors associated with the effect of pramipexole on symptoms of idiopathic REM sleep behavior disorder

BackgroundThe clinical effectiveness of pramipexole (PPX), a candidate treatment for idiopathic rapid eye movement sleep behavior disorder (iRBD), varies among individuals. This study investigates factors associated with PPX effectiveness for treating RBD symptoms.MethodsNinety-eight consecutive patients with RBD who had taken PPX or clonazepam (CNZP) for more than three months were enrolled. Factors associated with PPX effectiveness were examined: the ratio of REM sleep without atonia to total REM sleep (RWA/REM), length of RBD morbidity, frequency of vocalization or abnormal behavior, and Sniffin' Stick Test scores. These factors were also compared among the responders to PPX monotherapy, CNZP monotherapy, and PPX + CNZP combined therapy.ResultsPPX was efficacious in 61.7% (50/81) of the subject patients. RWA/REM was associated with PPX effectiveness. The cut-off rate of RWA/REM for predicting PPX effectiveness was estimated as 16.8%. Responders to PPX + CNZP combined therapy showed significantly higher RWA/REM and frequency of vocalization or dream enactment behavior than either responders to monotherapy with PPX or to CNZP.ConclusionPPX is probably applicable as an alternative to CNZP, especially for mild iRBD cases with a lower rate of RWA. Results of this study suggest that dopaminergic dysfunction can play a role in iRBD pathophysiology.     

Relationship between I-MIBG scintigrams and REM sleep behavior disorder in Parkinson’s disease

BackgroundUptake of ¹²³I-labeled meta-iodobenzylguanidine (MIBG) in myocardial scintigrams has been shown to be as low in patients with idiopathic RBD as in Parkinson’s disease (PD) patients.Aim for studyTo clarify whether the existence of RBD accelerates autonomic dysfunction in PD, we investigated the association between MIBG scintigraphic findings and RBD measures among non-dementia PD patients.Subjects &; methodsWe conducted clinical interviews to assess REM sleep behavior disorder (RBD) symptoms, and performed polysomnograms (PSG) recordings and MIBG scintigrams on 49 PD patients. The patients were divided into three groups (PD with clinical RBD, PD with subclinical RBD, and PD with normal REM sleep).ResultsPD patients with clinical RBD had reduced MIBG uptake as determined by heart-to-mediastinum ratios of the delayed image compared to those with subclinical RBD and those with normal REM sleep. Multiple linear regression analysis revealed that only the existence of RBD symptoms was significantly associated with reduced MIBG uptake among PD patients without dementia after adjusting for demographic and PD symptom-related variables.ConclusionPD patients with clinical RBD might suffer from a wider α-synuclein pathology, including reduced cardiac sympathetic ganglia function as reflected by a lowered MIBG uptake.     

Voxel-based magnetic resonance imaging study of structural brain changes in patients with idiopathic REM sleep behavior disorder

PurposeRapid eye movement (REM) sleep behavior disorder (RBD) is considered to result from dysfunction of the brain stem structures that regulate REM sleep. In this study, we investigated structural brain changes using magnetic resonance imaging (MRI) in patients with idiopathic RBD (iRBD) to determine structural brain alterations associated with the disorder.MethodsVoxel-based MRI morphometry was applied to 20 patients with iRBD and findings were compared with those from 18 age-matched controls.ResultsCompared with the controls, the patients with iRBD had significant gray matter volume reduction in the anterior lobes of the right and left cerebellum, tegmental portion of the pons, and left parahippocampal gyrus.ConclusionThe present study provides in vivo evidence suggesting that structural lesions of the brain stem are responsible for the occurrence of iRBD. In addition, the pattern of gray matter loss is consistent with morphological changes commonly observed in patients with Lewy body disease and multiple system atrophy, indicating that iRBD can share a common morphological abnormality with alpha-synucleinopathies.     

REM sleep behavior disorder and REM sleep without atonia in Parkinson's disease

OBJECTIVE: To determine the frequency of REM sleep behavior disorder (RBD) among patients with PD using both history and polysomnography (PSG) recordings and to further study REM sleep muscle atonia in PD. BACKGROUND: The reported occurrence of RBD in PD varies from 15 to 47%. However, no study has estimated the frequency of RBD using PSG recordings or analyzed in detail the characteristics of REM sleep muscle atonia in a large group of unselected patients with PD. METHODS: Consecutive patients with PD (n = 33) and healthy control subjects (n = 16) were studied. Each subject underwent a structured clinical interview and PSG recording. REM sleep was scored using a method that allows the scoring of REM sleep without atonia. RESULTS: One third of patients with PD met the diagnostic criteria of RBD based on PSG recordings. Only one half of these cases would have been detected by history. Nineteen (58%) of 33 patients with PD but only 1 of 16 control subjects had REM sleep without atonia. Of these 19 patients with PD, 8 (42%) did not present with behavioral manifestations of RBD, and their cases may represent preclinical forms of RBD associated with PD. Moreover, the percentage of time spent with muscle atonia during REM sleep was lower among patients with PD than among healthy control subjects (60.1% vs 93.2%; p = 0.003). CONCLUSIONS: RBD and REM sleep without atonia are frequent in PD as shown by PSG recordings.     

Effects of long-term use of clonazepam on nonrapid eye movement sleep patterns in rapid eye movement sleep behavior disorder

ObjectiveWe aim to analyze in detail the characteristics of nonrapid eye movement (NREM) sleep in drug-free patients with idiopathic rapid eye movement sleep behavior disorder (iRBD). We compare drug-free iRBD patients to both normal controls and drug-free patients with narcolepsy/RBD and evaluate the changes following the long-term use of bedtime clonazepam.Participants and methodsForty-six participants were recruited: 15 with iRBD (13 men, 2 women; mean age, 65.8 ± 4.39 years), 13 with narcolepsy/RBD (10 men, 3 women; mean age, 63.0 ± 6.73 years), and 18 normal controls (10 men, 8 women; mean age 69.4 ± 7.72 years). Sleep was video polysomnographically recorded and the RBD severity scale (RBDSS) was obtained. Chin electromyography (EMG) amplitude was quantitatively assessed and the atonia index was computed. Additionally, NREM sleep instability was evaluated using an automatic quantitative analysis. Participants with iRBD were re-evaluated after 2.75 ± 1.62 years of regular therapy with 0.5 to 1-mg clonazepam at bedtime.ResultsSlow transient electroencephalography (EEG) events were increased in iRBD and decreased in narcolepsy/RBD, while fast transient events decreased in iRBD and increased in narcolepsy/RBD. During rapid eye movement (REM) sleep the atonia index was reduced in both iRBD and narcolepsy/RBD groups and during NREM sleep atonia index was increased in iRBD participants, remaining low in narcolepsy/RBD participants. After long-term therapy with clonazepam, wakefulness after sleep onset was decreased together with an increase in both slow-wave sleep (SWS) and sleep stage 2, in which the latter reached statistical significance; sleep stages 1 and 2 instability significantly decreased and the duration of EEG transients also slightly but significantly decreased. Finally, chin tone was not modified by clonazepam.ConclusionsOur study confirms that clonazepam modifies some aspects of NREM sleep in iRBD participants with a decrease in its instability. Moreover, we also show that a complex modification of sleep chin atonia exists in these participants, which also involves NREM sleep; for iRBD more complex neuropathologic models encompassing REM sleep and NREM sleep mechanisms are needed.     

Factors associated with injury in REM sleep behavior disorder

ObjectiveAs factors associated with injury in rapid eye movement (REM) sleep behavior disorder (RBD) remain largely unknown, we aimed to identify such factors.MethodsWe surveyed consecutive idiopathic (iRBD) or symptomatic RBD patients seen between 2008 and 2010 regarding RBD-related injuries. Associations between injuries and clinical variables were determined with odds ratios (OR) and multiple logistic regression analyses. The primary outcome variables were injury and injury severity.ResultsFifty-three patients (40%) responded. Median age was 69 years, and 35 (73.5%) were men. Twenty-eight (55%) had iRBD. Twenty-nine (55%) reported injury, with 37.8% to self and 16.7% to the bed partner. 11.3% had marked injuries requiring medical intervention or hospitalization, including two (4%) subdural hematomas. iRBD diagnosis (OR = 6.8, p = 0.016) and dream recall (OR = 7.5, p = 0.03) were associated with injury; and iRBD diagnosis was independently associated with injury and injury severity adjusting for age, gender, DEB frequency, and duration. Falls (p = 0.03) were also associated with injury severity. DEB frequency was not associated with injury, injury severity, or falls.ConclusionsInjuries appear to be a frequent complication of RBD, although the relatively low response rate in our survey could have biased results. iRBD patients are more likely to suffer injury – and more severe injuries – than symptomatic RBD patients. In addition, recall of dreams was also associated with injury, and dream enactment behavior (DEB)-related falls were associated with more severe injuries. One in nine patients suffered injury requiring medical intervention. The frequency of DEB did not predict RBD-related injuries, highlighting the importance of timely initiation of treatment for RBD in patients having even rare DEB episodes. Future prospective studies will be necessary to define predictors of injury in RBD.