血管构筑异常所致Willis环变异及血流动力学改变对颅内单发动脉瘤破裂出血的影响

Multivariate predictors of intracranial aneurysm rupture by regression analysis of Willis circle variation and hemodynamic forces alteration arised from vascular structural abnormity

目的从影像学和血流动力学角度分析血管构筑异常所致Willis环变异及血流动力学改变对颅内动脉瘤（IA）破裂出血的影响。方法选择南方医科大学珠江医院神经外科自2010年11月至2011年11月收治的经数字减影血管造影（DSA）检查证实的IA患者223例，按有无破裂出血分为破裂组（182例）和未破裂组（41例）。通过DSA检查及三维重建图像观察认位置、大小、形态，判断Willis环变异类型，测量瘤体大小、载瘤动脉直径、瘤颈部横截面积、IA倾斜角以及双侧大脑前动脉A2段起始部夹角，计算队颈部横截面积与载瘤动脉直径比（AD）、瘤体与瘤颈比（AR）；行经颅彩色多普勒超声（TCCD）监测患者颅内血流动力学参数，计算切应力（WSS）、环壁张力（CWT）大小；通过受试者工作特征曲线（ROC）和Logistic回归分析影响颅内单发IA破裂出血的影响因素。结果IA患者左侧A1优势征（即Willis前环变异）的发生率均高于右侧，Willis前环变异的发生率略高于Willis后环变异：与未破裂组比较，破裂组患者年龄较大，动脉瘤倾斜角较大、AD较小，WSS降低、CWT增加，差异均有统计学意义（P〈0．05）；ROC曲线分析显示IA倾斜角、AD、WSS、CWT对评估队破裂出血的风险均有意义（曲线下面积分别为0．606、0．618、0．396、0．637）；Logistic回归分析结果显示：年龄、高血压Ⅲ级、IA倾斜角、AD和CWT是IA破裂出血的危险因素；A1优势征、小动脉瘤（2-5mm）和WSS是IA破裂出血的保护性因素。结论认患者存在明显的Willis环变异。年龄、高血压Ⅲ级、IA倾斜角、AD和CWT、A1优势征、小动脉瘤（2～5mm）和WSS与认破裂出血密切相关。准确评估这些因素对于队的防治有重要的临床意义。

Objective To explore the effect of Willis circle variation and hemodynamic forces alteration arised from vascular structural abnormity on intracranial aneurysm （IA） rupture using 3D- digital subtraction angiography （DSA） and transcranial color Doppler （TCCD） detection. Methods Two hundred and twenty-three patients with IA, admitted to and conformed by DSA in our hospital from November 2010 to November 2011, were divided into ruptured IA group （n=182） and un-ruptured IA group （n=41）. The 3D-DSA was applied in all patients to carefully evaluate the aneurysm sizes, locations, and morphous features, and to confirm the presence of A1 dominance and Willis circle variation. Moreover, aneurysmal neck area, diameter of parent artery, angle between A2 segments of bilateral anterior cerebral artery, angle between aneurysmal longitudinal axis and parent artery, aortic diameter （AD） and aspect ratio （AR） were measured with assistance of 3D-DSA images. Besides, TCCD was applied to all patients, and the hemodynamic parameters were recorded to calculate wall shear stress （WSS） and mechanical stretch. The risk factors of IA rupture were analyzed by receiver operating characteristic （ROC） curve and multivariate Logistic regression with emphasis on Willis circle variation and hemodynamic forces alteration. Results Whether it was in ruptured IA group or in un-ruptured IA group, the incidence rate of variation of anterior Willis circle was higher than that of variation of posterior Willis circle. A1 dominance on the left side was the most common asymmetry. As compared with those in un-ruptured IA group, statistically elder age, smaller AD, larger angle between aneurysmal longitudinal axis and parent artery, decreased WSS and increased mechanical stretch in the ruptured IA group were noted （P〈0.05）. ROC curve indicated that angle between aneurysmal longitudinal axis and parent artery, AD, WSS and mechanical stretch could be used to evaluate IA rupture （area under the curve： 0.606 0.618,0.396,0.637）. Age （OR=8.618, 95%CI： 2.866-25.917, P-M）.000）, hypertension （grade ⅢOR=16. 320, 95%CI： 1.628-163.556, P=0.018）, angle between aneurysmal longitudinal axis and parent artery （OR=3.053, 95%CI： 1.131-8.242, P=0. 028）, AD （OR=5.638, 95%CI： 1.507-20.251, P=0.008） and mechanical stretch （OR=4.230, 95%CI： 1.554-11.516, P=0.000） were risk factors of IA rupture. A1 dominance （OR=0.242, 95%CI： 0.074-0.785, P=0.018）, small aneurysms （2-5 mm, OR=0.207, 95%CI： 0.054-0.788, P=0.002） and WSS （OR=0.021, 95%CI： 0.060-0.672, P=0.009） were identified as protective factors. Conclusions Willis circle variation exists in IA patients. Age, hypertension （grade Ⅲ）, angle between aneurysmal longitudinal axis and parent artery, AD and mechanical stretch are risk factors oflA rupture, while A1 dominance, small aneurysm （2-5 mm） and WSS are identified as protective factors. Accurate assessment of these factors is of great clinical significance for the prevention and treatment of IA in the future.