Clinical and Polysomnographic Characterization of REM Sleep Behavior Disorder: Casuistic of a Portuguese Sleep Medicine Center

Abstract

Introduction: REM sleep behavior disorder (RBD) is diagnosed by clinical history of abnormal and complex movements during sleep and by polysomnographic findings. Accordingly, RBD may occur isolated (iRBD) or, frequently, in association with neurodegenerative diseases, namely synucleinopathies generally preceding its onset. Thereby, our aim was to characterize the clinical and video-polysomnography (vPSG) features of patients diagnosed with iRBD and RBD plus Parkinson disease (RBDPD); analyze the symptoms and signs (motor and non-motor) that RBDPD patients presented before the diagnosis of PD, to realize if there is any predictive factor for phenoconversion. Methods: Retrospective, observational and unicentric study. The study included all patients with a clinical diagnosis of RBD (isolated and associated with PD), according to the diagnostic criteria of DSM-5 and ICSD-3 and who underwent polysomnographic recording at the Sleep Medicine Center of a hospital. level III, between January 2008 and May 2021. Results: A total of 48 patients were included and divided in iRBD (27 patients) and RBDPD (21 patients) groups. We proceeded to a clinical, demographic and vPSG characterization and comparison. In both groups, the majority of patients were male and the average age of RBD diagnosis was 64-65 years. In iRBD group, the most reported manifestation was violent sleep movements. In this group, we found five patients with subtle motor signs. In the RBDPD group, the majority had a previous diagnosis of RBD, on average, about six years before. The most common clinical feature was the presence of vivid dreams with violent content. In the iRBD group, the percentage of RSWA was higher in the subgroup of patients with subtle motor signs and other premotor symptoms, namely depression (34.2%), than in patients without any of those features (31.6%). Conclusion: As we found, in the most of RBDDP group, RBD preceded the diagnosis of PD. Although it was not possible to obtain a correlation, as with clinical RBD, the percentage of RSWA should be considered a potential biomarker of phenocon-version in neurodegenerative disease. Early diagnosis of REM sleep anomalies, in a phase of subtil motor symptoms is essential and should be used as a biomarker to an earlier investigation, as DATscan, and therapeutic action.