Blood-brain barrier impairment and hypoperfusion are linked in cerebral small vessel disease

Objective

To investigate the link between blood-brain-barrier (BBB) permeability and cerebral blood flow (CBF) and the relation with white matter hyperintensities (WMH) in cerebral small vessel disease (cSVD).

Methods

Twenty-seven patients with cSVD received dynamic susceptibility contrast and dynamic contrast-enhanced MRI to determine CBF and BBB permeability (expressed as leakage rate and volume), respectively. Structural MRI were segmented into normal-appearing white matter (NAWM) and WMH, for which a perilesional zone was defined. In these regions, we investigated the BBB permeability, CBF, and their relation using Pearson correlation r.

Results

We found a decrease in CBF of 2.2 mL/min/100 g (p <0.01) and an increase in leakage volume of 0.7% (p <0.01) per mm closer to the WMH in the perilesional zones. Lower CBF values correlated with higher leakage measures in the NAWM and WMH (-0.53 <r <-0.40, p <0.05). This relation was also observed in the perilesional zones, which became stronger in the proximity of WMH (p = 0.03).

Conclusion

BBB impairment and hypoperfusion appear in the WMH and NAWM, which increase in the proximity of the WMH, and are linked. Both BBB and CBF are regulated in the neurovascular unit (NVU) and the observed link might be due to the physiologic regulation mechanism of the NVU. This link may suggest an early overall deterioration of this unit.