Impact of thrombus migration on clinical outcomes in patients with internal carotid artery occlusions and patent middle cerebral artery

Background: Patency of the middle cerebral artery (MCA) in acute ischemic stroke with internal carotid artery (ICA) occlusions is associated with less severe stroke and favorable outcomes. However, thrombus migration to distal intracranial vessels may lead to unfavorable outcomes. We investigated the influence of thrombus migration on clinical outcomes in patients with ICA occlusions and patent MCA. Materials and methods: We retrospectively analyzed patients with acute ischemic stroke compromising ICA occlusions and patent MCA who were consecutively admitted to our hospital between January 2006 and March 2016. Thrombus migration was assessed (1) by analyzing the discrepancies in arterial occlusion sites between initial imaging and follow-up imaging and (2) by analyzing how occlusion sites changed during endovascular therapy. Results: Thirty-eight patients (mean age: 74.9 years; 23 men, 15 women, median National Institutes of Health Stroke Scale score = 7.5) with ICA occlusions and patent MCA were ultimately included. We identified 10 patients (26%) with thrombus migration (spontaneous: 3; during endovascular therapy: 7). Patients with thrombus migration had higher rates of unfavorable functional outcomes (modified Rankin Scale scores 3–6 at 90 days) than those without thrombus migration (90% vs. 39%, p < .01). Multivariate analysis showed that thrombus migration was independently related to unfavorable functional outcomes (odds ratio, 42.9; 95% confidence interval, 1.5–1211.0; p = .03). Conclusion: Thrombus migration in cases of ICA occlusion with patent MCA is associated with poor prognosis. Careful monitoring is required under these conditions even if the initial clinical presentation is mild.