Diffusion Tensor Imaging (DTI) bei Patienten mit REM Sleep Behavior Disorder (RBD)

Introduction Idiopathic REM sleep behavior disorder (iRBD) - a parasomnia characterized by dream enactments – is a risk factor for the development of Parkinson's disease (PD) and other alpha-synucleinopathies. The pathophysiology of iRBD is likely due to a dysfunction of brainstem nuclei that regulate REM sleep. Material and Methods Diffusion tensor imaging (DTI) of the brain is a method for studying the microstructural brain tissue integrity in vivo. We investigated whether DTI detects microstructural abnormalities in brains of patients with iRBD - compared with age-matched controls - as a potential in vivo indicator for changes related to “preclinical (premotor)” PD neuropathology. Patients with iRBD (n=12) and age-matched healthy controls (n=12) were studied using a routine 1.5T MRI scanner. Whole-head DTI scans (measuring fractional anisotropy (FA), axial diffusivity (AD), a potential marker of neuronal loss and radial diffusivity (RD), a potential marker of myelin pathology, were analyzed without a priori hypothesis using tract-based spatial statistics (TBSS), a novel technique minimizing edge-related artifacts and alignment difficulties. Results Using group analysis, we found significant microstructural brain tissue changes (p < 0.0001) in the white matter of the brainstem (AD), the olfactory region (FA), the left temporal lobe (RD), the fornix (RD), the internal capsule (FA), the corona radiata (AD), the right visual stream (RD) and the right substantia nigra (AD) of the iRBD patients. Discussion These microstructural abnormalities were identified in regions known to either be involved in REM-sleep regulation (brainstem) and/or to exhibit neurodegenerative pathology in iRBD and/or early PD. The study suggests that iRBD-related microstructural abnormalities can be detected in vivo with DTI, a widely available MRI technique.