White matter and cortical changes in atypical parkinsonisms: A multimodal quantitative MR study

Objectives: To evaluate white matter and cortical changes in patients with parkinsonisms and healthy controls (HC), applying both hypothesis-free and regions of interest (ROI)-based advanced brain MR analyses. Methods: Twenty-five patients with Progressive Supranuclear Palsy - Richardson's Syndrome (PSP-RS), nine with cerebellar and nine with parkinsonian Multiple System Atrophy variants (MSA-C and MSA-P), forty-seven with Parkinson's Disease (PD) and twenty-seven HC underwent a 1.5 T brain-MR protocol including high-resolution 3D T1-weighted and 25-direction diffusion tensor imaging sequences. We performed cortical and white matter analysis by using vertex-based cortical thickness evaluation and Tract Based Spatial Statistics (TBSS), followed by a ROI-based cortical thickness analysis and probabilistic tractography of cortico-spinal tract (CST), and middle and superior cerebellar peduncles (MCP and SCP). Results: In PSP-RS, both ROIs-based and voxel-wise analyses demonstrated significant thinning of the pre-central cortices and diffuse white matter alterations involving supra- and infratentorial compartments. Along-tract tractography analysis of CST showed a significantly higher MD in PSP-RS vs PD and HC limited to the portion of the tract within the corona radiata. In MSA-C, a predominant involvement of MCPs was evident, while alterations in MCPs in MSA-P and in SCPs in PSP-RS and MSA-C were also present. Conclusion: Specific patterns of cortical and white matter changes in atypical parkinsonism patients reflect the neuropathological and clinical features of these disorders. This study shows that quantitative brain MR techniques can detect significant changes that help to elucidate the physiopathology of movement disorders and support their differential diagnosis.