The Clinical Phenotype of Idiopathic Rapid Eye Movement Sleep Behavior Disorder at Presentation: A Study in 203 Consecutive Patients.
To describe the clinical phenotype of idiopathic rapid eye movement (REM) sleep behavior disorder (IRBD) at presentation in a sleep center.
Clinical history review of 203 consecutive patients with IRBD identified between 1990 and 2014. IRBD was diagnosed by clinical history plus video-polysomnographic demonstration of REM sleep with increased electromyographic activity linked to abnormal behaviors.
Patients were 80% men with median age at IRBD diagnosis of 68 y (range, 50-85 y). In addition to the already known clinical picture of IRBD, other important features were apparent: 44% of the patients were not aware of their dream-enactment behaviors and 70% reported good sleep quality. In most of these cases bed partners were essential to convince patients to seek medical help. In 11% IRBD was elicited only after specific questioning when patients consulted for other reasons. Seven percent did not recall unpleasant dreams. Leaving the bed occurred occasionally in 24% of subjects in whom dementia with Lewy bodies often developed eventually. For the correct diagnosis of IRBD, video-polysomnography had to be repeated in 16% because of insufficient REM sleep or electromyographic artifacts from coexistent apneas. Some subjects with comorbid obstructive sleep apnea reported partial improvement of RBD symptoms following continuous positive airway pressure therapy. Lack of therapy with clonazepam resulted in an increased risk of sleep related injuries. Synucleinopathy was frequently diagnosed, even in patients with mild severity or uncommon IRBD presentations (e.g., patients who reported sleeping well, onset triggered by a life event, nocturnal ambulation) indicating that the development of a neurodegenerative disease is independent of the clinical presentation of IRBD.
We report the largest IRBD cohort observed in a single center to date and highlight frequent features that were not reported or not sufficiently emphasized in previous publications. Physicians should be aware of the full clinical expression of IRBD, a sleep disturbance that represents a neurodegenerative disease.
A commentary on this article appears in this issue on page 7.
Fernández-Arcos A
,Iranzo A
,Serradell M
,Gaig C
,Santamaria J
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Detection of α-synuclein in CSF by RT-QuIC in patients with isolated rapid-eye-movement sleep behaviour disorder: a longitudinal observational study.
Isolated rapid-eye-movement (REM) sleep behaviour disorder (IRBD) can be part of the prodromal stage of the α-synucleinopathies Parkinson's disease and dementia with Lewy bodies. Real-time quaking-induced conversion (RT-QuIC) analysis of CSF has high sensitivity and specificity for the detection of misfolded α-synuclein in patients with Parkinson's disease and dementia with Lewy bodies. We investigated whether RT-QuIC could detect α-synuclein in the CSF of patients with IRBD and be used as a biomarker of prodromal α-synucleinopathy.
In this longitudinal observational study, CSF samples were obtained by lumbar puncture from patients with video polysomnography-confirmed IRBD recruited at a specialised sleep disorders centre in Barcelona, Spain, and from controls free of neurological disease. CSF samples were stored until analysed using RT-QuIC. After lumbar puncture, participants were assessed clinically for neurological status every 3-12 months. Rates of neurological disease-free survival were estimated using the Kaplan-Meier method. Disease-free survival rates were assessed from the date of lumbar puncture to the date of diagnosis of any neurodegenerative disease, or to the last follow-up visit for censored observations.
52 patients with IRBD and 40 healthy controls matched for age (p=0·20), sex (p=0·15), and duration of follow-up (p=0·27) underwent lumbar puncture between March 23, 2008, and July 16, 2017. The CSF α-synuclein RT-QuIC assay was positive in 47 (90%) patients with IRBD and in four (10%) controls, resulting in a sensitivity of 90·4% (95% CI 79·4-95·8) and a specificity of 90·0% (95% CI 76·9-96·0). Mean follow-up from lumbar puncture until the end of the study (July 31, 2020) was 7·1 years (SD 2·8) in patients with IRBD and 7·7 years (2·9) in controls. During follow-up, 32 (62%) patients were diagnosed with Parkinson's disease or dementia with Lewy bodies a mean 3·4 years (SD 2·6) after lumbar puncture, of whom 31 (97%) were α-synuclein positive at baseline. Kaplan-Meier analysis showed that patients with IRBD who were α-synuclein negative had lower risk for developing Parkinson's disease or dementia with Lewy bodies at 2, 4, 6, 8, and 10 years of follow-up than patients with IRBD who were α-synuclein positive (log-rank test p=0·028; hazard ratio 0·143, 95% CI 0·019-1·063). During follow-up, none of the controls developed an α-synucleinopathy. Kaplan-Meier analysis showed that participants who were α-synuclein negative (ie, five patients with IRBD plus 36 controls) had lower risk of developing Parkinson's disease or dementia with Lewy bodies at 2, 4, 6, 8 and 10 years after lumbar puncture than participants who were α-synuclein positive (ie, 47 patients with IRBD plus four controls; log-rank test p<0·0001; hazard ratio 0·024, 95% CI 0·003-0·177).
In patients with IRBD, RT-QuIC detects misfolded α-synuclein in the CSF with both sensitivity and specificity of 90%, and α-synuclein positivity was associated with increased risk of subsequent diagnosis of Parkinson's disease or dementia with Lewy bodies. Detection of α-synuclein in the CSF represents a potential prodromal marker of Parkinson's disease and dementia with Lewy bodies. If these findings are replicated in additional cohorts, detection of CSF α-synuclein by RT-QuIC could be used to enrich IRBD cohorts in neuroprotective trials, particularly when assessing interventions that target α-synuclein.
Department of Health and Social Care Policy Research Programme, the Scottish Government, and the Weston Brain Institute.
Iranzo A
,Fairfoul G
,Ayudhaya ACN
,Serradell M
,Gelpi E
,Vilaseca I
,Sanchez-Valle R
,Gaig C
,Santamaria J
,Tolosa E
,Riha RL
,Green AJE
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Risk and predictors of dementia and parkinsonism in idiopathic REM sleep behaviour disorder: a multicentre study.
Idiopathic REM sleep behaviour disorder (iRBD) is a powerful early sign of Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. This provides an unprecedented opportunity to directly observe prodromal neurodegenerative states, and potentially intervene with neuroprotective therapy. For future neuroprotective trials, it is essential to accurately estimate phenoconversion rate and identify potential predictors of phenoconversion. This study assessed the neurodegenerative disease risk and predictors of neurodegeneration in a large multicentre cohort of iRBD. We combined prospective follow-up data from 24 centres of the International RBD Study Group. At baseline, patients with polysomnographically-confirmed iRBD without parkinsonism or dementia underwent sleep, motor, cognitive, autonomic and special sensory testing. Patients were then prospectively followed, during which risk of dementia and parkinsonsim were assessed. The risk of dementia and parkinsonism was estimated with Kaplan-Meier analysis. Predictors of phenoconversion were assessed with Cox proportional hazards analysis, adjusting for age, sex, and centre. Sample size estimates for disease-modifying trials were calculated using a time-to-event analysis. Overall, 1280 patients were recruited. The average age was 66.3 ± 8.4 and 82.5% were male. Average follow-up was 4.6 years (range = 1-19 years). The overall conversion rate from iRBD to an overt neurodegenerative syndrome was 6.3% per year, with 73.5% converting after 12-year follow-up. The rate of phenoconversion was significantly increased with abnormal quantitative motor testing [hazard ratio (HR) = 3.16], objective motor examination (HR = 3.03), olfactory deficit (HR = 2.62), mild cognitive impairment (HR = 1.91-2.37), erectile dysfunction (HR = 2.13), motor symptoms (HR = 2.11), an abnormal DAT scan (HR = 1.98), colour vision abnormalities (HR = 1.69), constipation (HR = 1.67), REM atonia loss (HR = 1.54), and age (HR = 1.54). There was no significant predictive value of sex, daytime somnolence, insomnia, restless legs syndrome, sleep apnoea, urinary dysfunction, orthostatic symptoms, depression, anxiety, or hyperechogenicity on substantia nigra ultrasound. Among predictive markers, only cognitive variables were different at baseline between those converting to primary dementia versus parkinsonism. Sample size estimates for definitive neuroprotective trials ranged from 142 to 366 patients per arm. This large multicentre study documents the high phenoconversion rate from iRBD to an overt neurodegenerative syndrome. Our findings provide estimates of the relative predictive value of prodromal markers, which can be used to stratify patients for neuroprotective trials.
Postuma RB
,Iranzo A
,Hu M
,Högl B
,Boeve BF
,Manni R
,Oertel WH
,Arnulf I
,Ferini-Strambi L
,Puligheddu M
,Antelmi E
,Cochen De Cock V
,Arnaldi D
,Mollenhauer B
,Videnovic A
,Sonka K
,Jung KY
,Kunz D
,Dauvilliers Y
,Provini F
,Lewis SJ
,Buskova J
,Pavlova M
,Heidbreder A
,Montplaisir JY
,Santamaria J
,Barber TR
,Stefani A
,St Louis EK
,Terzaghi M
,Janzen A
,Leu-Semenescu S
,Plazzi G
,Nobili F
,Sixel-Doering F
,Dusek P
,Bes F
,Cortelli P
,Ehgoetz Martens K
,Gagnon JF
,Gaig C
,Zucconi M
,Trenkwalder C
,Gan-Or Z
,Lo C
,Rolinski M
,Mahlknecht P
,Holzknecht E
,Boeve AR
,Teigen LN
,Toscano G
,Mayer G
,Morbelli S
,Dawson B
,Pelletier A
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