The Clinical Phenotype of Idiopathic Rapid Eye Movement Sleep Behavior Disorder at Presentation: A Study in 203 Consecutive Patients

Abstract

Objective

To describe the clinical phenotype of idiopathic rapid eye movement (REM) sleep behavior disorder (IRBD) at presentation in a sleep center.

Methods

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.

Results

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.

Conclusions

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.

Commentary

A commentary on this article appears in this issue on page 7.

Significance

IRBD is an early manifestation of a neurodegenerative disease. This study describes the clinical findings of a large IRBD cohort that was identified over a long observational period. Using rigorous electromyographic and audiovisual criteria on polysomnography for the diagnosis of IRBD, the detailed description of 203 consecutive patients confirmed previous well-known observations and highlighted important findings that were nor recognized or not sufficiently emphasized in the medical literature. General physicians, sleep specialists and neurologists should be aware of the full profile of IRBD described in this study to improve the early detection and correct identification of this condition. This is important for patient management and counseling and will be of great interest when neuroprotective strategies become available.

bed partner, dream-enacting behaviors, idiopathic REM sleep behavior disorder, medical consultation, nightmares, sleep quality