BACKGROUND The middle cerebral artery (MCA) bifurcation represents the most frequent location for intracranial aneurysms. Often, the aneurysmal dome can hide the origin of perforating arteries from the M1 segment during the surgical clipping causing ischemic lesions and worse clinical outcome. The aim of this paper is to analyze the association between the orientation of the aneurysm sac and the clinical and radiological outcomes after surgical clipping. METHODS Data from 50 MCA bifurcation clipped aneurysms in 47 patients were collected retrospectively. Three different groups were identified according to the aneurysmal sac orientation: anterior-inferior, posterior and superior. A possible association between the aneurysmal sac projection and the outcome was searched through a univariable logistic regression analysis. RESULTS Statistical analysis showed significant correlation between the radiologic evidence of post-operative ischemia in the posterior group (p = 0.046, RR = 1.65) and an increased risk in the superior orientation group (p = 0.145, RR = 1.38). The anterior-inferior group was, instead, significantly associated with no evidence of radiologic ischemia (p = 0.0019, RR = 0.58). CONCLUSION The orientation of the aneurysmal dome and sac represents a fundamental feature to be considered during the surgical clipping of the MCA aneurysms. Indeed, its posterior and superior projection is associated with a higher incidence of radiologic ischemic lesions due to the origin of perforating arteries from M1 segment behind the aneurysmal sac. The anterior-inferior orientation, on the contrary, is associated with a lower risk.

中文翻译：

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与夹闭的大脑中动脉分叉动脉瘤解剖方向相关的临床和放射学结果

背景 大脑中动脉 (MCA) 分叉是颅内动脉瘤最常见的位置。通常，在手术夹闭过程中，动脉瘤圆顶会隐藏 M1 段的穿通动脉起源，从而导致缺血性病变和更差的临床结果。本文的目的是分析动脉瘤囊的方向与手术夹闭后的临床和放射学结果之间的关系。方法回顾性收集47例患者的50个MCA分叉夹闭动脉瘤的数据。根据动脉瘤囊方向确定了三个不同的组：前-下、后和上。通过单变量逻辑回归分析搜索动脉瘤囊投影与结果之间的可能关联。结果 统计分析显示，后路组术后缺血的影像学证据（p = 0.046，RR = 1.65）与上位组风险增加（p = 0.145，RR = 1.38）之间存在显着相关性。相反，前下组与无影像学缺血证据显着相关（p = 0.0019，RR = 0.58）。结论 动脉瘤圆顶和囊的方向代表了在 MCA 动脉瘤的外科夹闭过程中需要考虑的基本特征。事实上，由于穿支动脉起源于动脉瘤囊后面的 M1 段，其后部和上部投影与较高的放射学缺血性病变发生率相关。相反，前下方向与较低的风险相关。