大脑前动脉A1段形态学特点与前交通动脉瘤的关系

The relationship between the morphological features of A1 segment of anterior cerebral artery and anterior communicating artery aneurysms

目的分析大脑前动脉A1段的形态学特点及其与前交通动脉瘤形成和指向的关系,以提高开颅夹闭术的预见性和指导血管内栓塞术中微导管塑形。方法回顾性分析264例前交通动脉瘤及随机选取的同期296例其他脑血管疾病的数字减影脑血管造影检查资料。A1段形态上可分为弧形(Ⅰa型:上弧形,Ⅰb型:下弧形),"S"形(Ⅱa型:反横"S"形,Ⅱb型:横"S"形),"近线"形(Ⅲ型)及不显影。动脉瘤依瘤体指向分为:前下型、前上型、后上型、后下型及复杂型。结果①双侧A1段形态:前交通动脉瘤组,Ⅰa型158侧,Ⅰb型11侧,Ⅱa型35侧,Ⅱb型87侧,Ⅲ型171侧,缺如66侧。其他脑血管病组,Ⅰa型195侧,Ⅰb型20侧,Ⅱa型47侧,Ⅱb型74侧,Ⅲ型217侧,缺如39侧。前交通动脉瘤组A1段不显影较其他脑血管病组多(掊2=11.482,P=0.001)。②前交通动脉瘤指向:前上型121例,前下型105例,复杂型16例,后下型12例,后上型10例。③优势显影侧A1段形态与动脉瘤指向的关系:A1段形态与动脉瘤指向之间关系密切(掊2=221.859,P<0.01;C=0.619,P<0.01)。当A1段为Ⅰa型或Ⅱa型,动脉瘤指向一般向下;A1段为Ⅰb型或Ⅱb型,动脉瘤指向一般朝上;当A1段为Ⅲ型时,动脉瘤指向可向上、向下及复杂形态。结论大脑前动脉A1段变异与前交通动脉瘤形成有关。A1段形态以"近线"形、上弧形和横"S"形多见。前交通动脉瘤指向以前上型与前下型多见。认识A1段形态与前交通动脉瘤指向的关系对动脉瘤手术有指导意义。

Objective To improve the predictability of surgical clipping and guide the steam shaping of mi- crocatheters in endovascular embolization by analyzing the association of morphological features of A1 segment of an- terior cerebral artery （ACA） with formation and classification of anterior communicating artery aneurysms （ACoAA）. Methods Digital subtraction angiography data of 264 cases of ACoAA and 296 cases of other cerebral vascular dis- eases were analyzed retrospectively. The morphology of A1 segment of ACA was divided into four different patterns in- cluding “arc” pattern （type I a： convex shape, type I b： concave shape）, “S” pattern （type Ⅱ a： inverse lateral “s” shape, type Ⅱ b： lateral “s” shape）, approximate straight-line shape （typeⅢ） and non-development. According to the direction of aneurysm protrusion, the ACoAA were divided into 5 types including anterior-inferior type, anterior- superior type, posterior-superior type, posterior-inferior type and complicated type. Results Among 264 ACoAA pa- tients, the morphology of A1 segment of ACA was type I a in 158 sides, type I b in 11, type Ⅱ a in 35, type Ⅱb in 87, type Ⅲ in 171 and absence in 66. The morphology of A1 segment of ACA in 296 patients with other cerebral vascular diseases was type I a in 195 sides, type I b in 20, type Ⅱ a in 47, type Ⅱb in 74, type Ⅲ in 217 and ab-sence in 39. The no-visualization of A1 segment of ACA occurred was more frequent in the ACoAA group than in control group （X2 = 11.482, P = 0.001）. The direction of ACoAA in 264 patients were anterior-superior type in 121 cases, anterior-inferior type in 105, complicated type in 16, posterior-inferior type in 12 and posterior-superior type in 10. The correlation between the morphology of dominant A1 segment of ACA and direction of ACoAA was signifi- cant （X2 = 221.859, P = 0.000; C = 0.619, P = 0.000）. The direction of ACoAA was downward at the type I a/ type Ⅱ a, upward at type [ b/ type Ⅱ b, upward or downward or complicated at type Ⅲ. Conclusions The variation of A1 segment of ACA is relation to the formation of ACoAA. The A1 segment of ACA often appears as approximate straight-line, convex and lateral “s” shape. The common directions of ACoAA are anterior-superior and anterior-inferi- or type. The understanding of relationship between morphology of A1 segment of ACA and direction of ACoAA will help guide surgical procedures.