Cerebrovascular hemodynamics association with brain structure and function in Multiple Sclerosis

Abstract

BackgroundVascular risk factors seem to contribute to disease progression in Multiple Sclerosis (MS), but the mechanistic connection between vascular risk and MS is unknown. Understanding cerebrovascular hemodynamics (CVH) in MS may help advance our understanding of the link between vascular risk and MS. ObjectivesExamine the relationship between CVH [dynamic cerebral autoregulation (dCA) and vasoreactivity (VR)] and brain structure (MRI) and function (cognition, and gait) in individuals with MS. MethodsTranscranial Doppler ultrasound (TCD) was utilized to assess two key markers of CVH: dCA and VR. dCA (reported as phase and gain) is calculated from the spontaneous blood pressure and flow velocity oscillations. VR is calculated as the slope of change in cerebral blood flow velocity in response to end-tidal CO2. Global gray matter (GM), white matter (WM), WM hyperintensity (WMH) volumes and WM lesion counts were measured from brain MRI. All participants underwent detailed cognitive and gait assessments. ResultsEighty participants were included (age 44 ± 11, 26 % male); 75 had relapsing-remitting MS (94 %), with disease duration of 8 (11) years [median (IQR)] since MS diagnosis and an Expanded Disability Status Scale (EDSS) of 2.0 (4.0). Higher phase (better dCA) was associated with greater GM volume, lower WHM burden and higher cognitive scores in the memory and global cognitive domains (all P values <0.05). There was no relationship between CVH and gait speed in our study participants. There was no relationship between VR and any measures of brain structure and function. ConclusionsMore efficient cerebral autoregulation is associated with better brain structure (larger GM and lower WMH volumes) and function (cognition, but not gait) in patients with MS.