Unstable Cerebral Hemodynamics in Carotid Artery Occlusion and Large Hemispheric Stroke: A Cerebral Blood Flow Volume Study

Purpose. In chronic internal carotid artery (ICA) occlusion, cere bral hemodynamics are likely to be stable due to collateral flow. The authors evaluated cerebral hemodynamics in ICA occlusion using the sonographic method of cerebral blood flow volume (CBVF) measurement to find differences that might identify patients with large hemispheric stroke in ICA occlusion.Methodand Results. The ultrasound method of CBVF measurement was used, which represents the sum of flow volumes of both internal carotid and both vertebal arteries. CBVF was measured in 29 patients with ICA occlusion including patients with (1) chronic ICA occlusion without acute minor stroke, (2) chronic ICA occlusion with acute minor stroke, (3) acute minor stroke due to acute ICA occlusion, and (4) ICA occlusion and large hemispheric stroke. In ICA occlusion, overall CBVF is lower compared to healthy volunteers, due to a significant reduction of CBVF in groups 3 and 4. Comparing groups, there were no differences in CBVF between groups 1, 2, and 3. CBVF in group 4 is reduced compared to all other groups. By receiver-operating characteristic analysis, a CBVF cutoff value for large hemi spheric stroke was computed with a sensitivity of 100% and a specificity of 95.8%.Conclusion. Stroke due to acute ICA occlusion is associated with decreased CBVF compared to chronic ICA occlusion. Moreover, ICA occlusion and large hemispheric stroke are associated with decreased CBVF compared to all other groups, indicating instability of cerebral hemodynamics. CBVF measurement thus may be a useful tool in predicting large middle cerebral artery stroke early in ICA occlusion.