MIBG Cardiac Scintigraphy as a Potential Biomarker That Reflects Severity in Idiopathic REM Sleep Behavior Disorder

Abstract Study Objectives: 123I-metaiodobenzylguanidine (MIBG) cardiac scintigraphy was performed to demonstrate the correlation with clinical characteristics of patients with idiopathic REM sleep behavior disorder (iRBD) and we found the factors that are associated with neurodegenerative diseases. Methods: All subjects including 39 patients with iRBD and 17 healthy controls underwent MIBG cardiac scintigraphy to assess cardiac autonomic dysfunction. The iRBDs were confirmed by in-lab overnight polysomnography. Receiver operating curve was performed to determine cut-off value of early and delayed heart to mediastinum ratio (HMR) in patients with iRBD. Based on each cut-off value, comparison analysis about RWA was performed by dividing into two groups within iRBD patients.Results: MIBG uptake below the cut-off value is associated with higher REM sleep without atonia (RWA). The lower HMR had significantly higher RWA (%) both with the cut-off value of early (11.0±5.6 VS 29.3±23.2, p=0.018) and delayed HMR (9.1±4.3 VS 30.0±22.9, p=0.011).Conclusion: This study suggests that MIBG uptake is a potential biomarker of the severity of RWA in iRBD.