LAUSR

Aim: We sought to determine whether the extent of chronic white matter hyper-intensities (WMH) and white matter hypo-perfusion (WMHP), as markers of cerebral small vessel disease (CSVD), were associated with poor collateral flow in acute ischemic stroke as a potential cause of unfavorable functional outcome. Methods: Acute ischemic stroke patients within 12 hours of symptom onset with complete baseline and follow-up clinical data, who: (1) had large vessel occlusion in anterior circulation, (2) underwent baseline perfusion CT (CTP), (3) had 24-hour MRI were prospectively recruited. The volume of WMH was measured in the unaffected hemisphere on MRI semi-automatically. WMHP was measured as Delay Time (DT)>2s in white matter of unaffected hemisphere on CTP. Quality of Collateral flow was defined by the volume ratio of DT>3s/DT>6s on CTP. Unfavorable functional outcome was 90-day modified Rankin Scale (mRS)>2. The association between volumes of WMH, WMHP, and collateral flow were evaluated using univariate and multivariate generalized linear models. We also assessed the relationship between WMH, WHMP, and functional outcome with logistic regression. Results: There were 96 (66.6±12.81 years old, 35 female) ischemic stroke patients, and 51 were due to large artery atherosclerosis (LAA). In all patients, after multivariate adjustment, WMH volume (5.6±7.11ml) did not correlate with collateral flow (coefficient -0.01, 95% CI -0.03 to 0, P=0.09), although it was marginally associated with unfavorable outcome (Odds Ratio: 1.08, p=0.06, 95% CI 1 to 1.17). In all patients, WMHP volume (8.6±8.54ml) did not correlate with collateral flow (coefficient -0.01, 95% CI -0.01 to 0, P=0.29). However, in the LAA subgroup, WMH volume was strongly related to poorer collateral flow, i.e. lower DT>3s/DT>6s ratio(coefficient -0.03, 95% CI -0.04 to -0.01, P=0.01). WMHP volume was also correlated with poor collateral flow (coefficient -0.01, 95% CI -0.02 to 0, P=0.02). Conclusion: CSVD may contribute to poor collateral flow in acute stroke, especially in patients with LAA. This potentially explains the association between CSVD and poor acute stroke outcomes.