BackgroundLeukoaraiosis and collateral blood flow are processes that involve small vessels, the former related to flow within the deep perforating arterioles and the latter involving the small, cortical pial-pial connections, both of which are independently used to predict cerebrovascular events and treatment outcomes. The aim of this study was to investigate their relationship to each other.MethodsWe retrospectively reviewed patients who underwent mechanical thrombectomy for stroke with pre-procedural CT imaging within 24 hours of the onset of symptoms. Leukoaraiosis was graded by the total Fazekas score on non-contrast CT, periventricular white matter (PVWM) and deep white matter (DWM) scores, both ranging from 0 to 3. Collateral cerebral blood flow was measured by the American Society of Interventional and Therapeutic Radiology/Society of Interventional Radiology (ASITN/SIR) collateral scale.Results178 patients were included with a mean age of 67.6±14.8 years. We found an inverse relationship between total Fazekas score and collateral flow (p<0.0001). Among patients with good collaterals, 75.1% had total Fazekas scores of 0–2, compared with 36.6% of patients with moderate collaterals and 32.7% of patients with poor collaterals with total Fazekas scores of 0–2. Mean Fazekas scores were 1.6±1.5, 3.1±1.5 and 3.4±1.6 for good, moderate and poor collaterals, respectively (p<0.0001). On multivariate analysis, total Fazekas score was the only variable independently associated with collateral status (p<0.0001).ConclusionsIncreasing severity of leukoaraiosis is associated with poor collateral grade among ischemic stroke patients with anterior circulation large vessel occlusion. These findings suggest that leukoaraiosis may be a marker for global cerebrovascular dysfunction.