Spinal cord involvement and cardiovascular autonomic dysfunction in Parkinson's disease

Patients with Parkinson's disease (PD) frequently present autonomic cardiovascular dysfunction. This study investigated the involvement of autonomic centers in the upper thoracic spinal cord in cardiovascular dysfunction in patients with PD using multimodal MRI and markers of orthostatic hypotension. We recruited 26 patients with PD, stratified based on the presence (PD_RBD(+), n = 11) or absence (PD_RBD(-), n = 15) of rapid-eye movement sleep behavior disorder (RBD), and 22 matched healthy controls (HC). Participants underwent multimodal MRI of the cervical and upper thoracic spinal cord. Quantitative metrics, including T1 relaxation times, diffusion metrics, and magnetization transfer ratio (MTR) values, were extracted from gray and white matter spinal cord regions. MRI metrics were compared across groups and examined for associations with blood pressure drops, both cross-sectionally and longitudinally, as indicators of orthostatic hypotension. No significant differences in MRI metrics were found between patients with PD and HCs, nor between PD subgroups. A multivariate analysis pooling all MRI metrics together allowed for the separation of HCs and PD subgroups. In the PD_RBD(+) subgroup, positive correlations were found between systolic blood pressure drop and T1 relaxation times as well as mean diffusivity values at the cervicothoracic junction. Longitudinal changes in blood pressure drops were associated with MRI measurements after adjusting for baseline blood pressure, age, and sex, suggesting that these metrics may serve as potential markers of future blood pressure changes. These preliminary findings suggest that spinal cord quantitative MRI measurements at the cervicothoracic junction may be associated with orthostatic hypotension in PD_RBD(+) patients.