Abstract T P103: Vertebral Artery Hypoplasia Should Play Important Role for Posterior Circulation Ischemia

Abstract

Purpose: Vertebral artery hypoplasia (VAH) is congenital anatomical variation, which is frequently observed in clinical situation. In previous reports, it was not unclear whether VAH was the independent risk factor for posterior circulation ischemia. The purpose of this study is to evaluate an impact of VAH on posterior circulation ischemia. Methods: Subjects were patients with acute ischemic stroke who underwent brain MRI and carotid ultrasonography. The diameter of vessel and flow velocities of extracranial vertebral artery (VA) was measured by carotid ultrasonography. Diagnostic criteria of VAH was as follows: 1) diameter of VA <2.5mm, 2) diameter of VA <3.0mm and a side difference equal or greater than 1:1.7, 3) diameter of VA <3.0mm, peak systolic velocity <40cm/sec, and resistance index value >0.75. We divided all patients into three groups by the location of the acute ischemic stroke evaluated by MRI: ischemic lesion on posterior circulation (P group), on anterior circulation (A group), and multiple lesions on both anterior and posterior circulation (AP group). Then, the prevalence rate of VAH was compared between P group and A+AP group. In order to evaluate independent factors of VA occlusion, we conducted multivariate regression analyses. Results: We evaluated a total of 129 consecutive patients (87 male, median age; 71 years). P group was 36 patients, and A+AP group was 93 patients. VAH was seen in 39 patients (31.5%), and VA occlusion was found in 15 patients. The prevalence rate of VAH in P group (44.4%) was significantly higher than in A+AP group (24.7%, p=0.034). In univariate analysis, the patients with VA occlusion were higher rates of hypertension (p=0.066), large artery atherosclerosis (p=0.095), posterior circulation ischemia (p=0.001), and the presence of VAH (p=0.038). Multivariate regression analysis demonstrated that large artery atherosclerosis (odds ratio, 6.3; 95% confidence interval, 1.3-30.1), posterior circulation ischemia (odds ratio, 12.0; 95% confidence interval, 2.8-51.2) and VAH (odds ratio, 4.2; 95% confidence interval, 1.2-15.0) were independently associated with the presence of VA occlusion. Conclusion: VAH was independent factor of VA occlusion, and should be associated with posterior circulation ischemia.