Disruptions of deep medullary veins and MRI indices of glymphatic function in cerebral small vessel disease

BackgroundDisruptions of deep medullary veins (DMV) have been associated with the radiological severity and cognitive impairment observed in cerebral small vessel disease (SVD). Glymphatic dysfunction may serve as a potential mechanism underlying these associations.ObjectiveWe aimed to clarify the associations between DMV disruptions, MRI indices previously hypothesized as related to glymphatic function, white matter hyperintensities (WMH), and cognitive impairment in SVD.MethodsThis cross-sectional study included 133 SVD participants. DMV disruptions were visually rated on susceptibility-weighted imaging (SWI). Five MRI indices related to glymphatic function were measured: the diffusion tensor imaging along the perivascular space (DTI-ALPS), free water (FW) fraction, choroid plexus (Cp) volumes, perivascular spaces in basal ganglia (BG-PVS) and white matter (WM-PVS).ResultsHigher DMV scores were associated with higher WMH volumes (β = 0.55, p < 0.001) and lower Montreal Cognitive Assessment (MoCA) scores (β = -0.24, p = 0.003). Higher DMV scores were correlated with lower DTI-ALPS values, higher FW fraction, higher volumes in Cp, BG-PVS, and WM-PVS (all p < 0.001). DTI-ALPS values and BG-PVS volumes mediated the associations between DMV scores and WMH volumes, with only BG-PVS volumes mediating the associations between DMV scores and MoCA scores.ConclusionsOur results suggested that DMV disruptions contribute to WMH burden and cognitive impairment in SVD. This effect could be mediated by MRI markers indicative of glymphatic dysfunction, particularly the enlargement of BG-PVS.