Abstract：
OBJECTIVE: Congenital external carotid-internal carotid artery (EC-ICA) anastomosis is a cervical arterial variation that was initially reported, based on anatomic dissection, from Japan in 2000. The purpose of this report is to show the characteristic radiological findings of this extremely rare cervical arterial variation.
METHODS: We analyzed nine cases, including six previously reported cases and three cases that we recently experienced. Three of the six previously reported cases were from Japan, and the remaining three cases were from Korea. MR angiography (4), CT angiography (2), catheter angiography (2) and autopsy (1) were used as diagnostic modalities.
RESULTS: The study population included eight men and one woman. Anastomosis was seen on the left side in seven cases and the right side in two cases, and it was located at the level of the C1/2-C2/3 intervertebral space. In all cases, ECA was larger than the ICA at the level of their origins. In four cases, the ICA was extremely small in caliber. In one case, the ICA may have been occluded postnatally, and its configuration was similar to that of the nonbifurcating cervical carotid artery (CCA). With the exception of this occluded case, the carotid bifurcation and EC-ICA anastomosis formed a large arterial ring in all cases.
CONCLUSIONS: EC-ICA anastomosis can be regarded as a variant of the nonbifurcating CCA because if the most proximal segment of the small ICA is occluded, nonbifurcating CCA may form. EC-ICA anastomosis is located between the C1/2-C2/3 intervertebral space and may be formed by the remnants of the proatlantal artery I.
METHODS: We analyzed nine cases, including six previously reported cases and three cases that we recently experienced. Three of the six previously reported cases were from Japan, and the remaining three cases were from Korea. MR angiography (4), CT angiography (2), catheter angiography (2) and autopsy (1) were used as diagnostic modalities.
RESULTS: The study population included eight men and one woman. Anastomosis was seen on the left side in seven cases and the right side in two cases, and it was located at the level of the C1/2-C2/3 intervertebral space. In all cases, ECA was larger than the ICA at the level of their origins. In four cases, the ICA was extremely small in caliber. In one case, the ICA may have been occluded postnatally, and its configuration was similar to that of the nonbifurcating cervical carotid artery (CCA). With the exception of this occluded case, the carotid bifurcation and EC-ICA anastomosis formed a large arterial ring in all cases.
CONCLUSIONS: EC-ICA anastomosis can be regarded as a variant of the nonbifurcating CCA because if the most proximal segment of the small ICA is occluded, nonbifurcating CCA may form. EC-ICA anastomosis is located between the C1/2-C2/3 intervertebral space and may be formed by the remnants of the proatlantal artery I.
摘要：
目的：先天性颈外动脉-颈内动脉（EC-ICA）吻合术是最初报道的颈部动脉变异，基于解剖解剖，2000年，日本。本报告的目的是显示这种极为罕见的宫颈动脉变异的特征性放射学发现。
方法：我们分析了9例，包括以前报告的6例病例和我们最近经历的3例病例。先前报告的6例病例中有3例来自日本,其余三例来自韩国。MR血管造影(4),CT血管造影(2),导管血管造影(2)和尸检(1)被用作诊断模式.
结果：研究人群包括8名男性和1名女性。左侧吻合7例，右侧吻合2例，它位于C1/2-C2/3椎间隙的水平。在所有情况下,ECA在起源水平上比ICA大。在四个案例中，ICA的口径非常小。在一个案例中,ICA可能在出生后被阻塞，其结构与非分叉颈颈动脉（CCA）相似。除了这个闭塞的案例，在所有情况下，颈动脉分叉和EC-ICA吻合都形成了大动脉环。
结论：EC-ICA吻合术可以被视为非分叉CCA的变体，因为如果小ICA的最近段被闭塞，可能形成非分叉CCA。EC-ICA吻合位于C1/2-C2/3椎间隙之间，可能由前动脉I的残余形成。
方法：我们分析了9例，包括以前报告的6例病例和我们最近经历的3例病例。先前报告的6例病例中有3例来自日本,其余三例来自韩国。MR血管造影(4),CT血管造影(2),导管血管造影(2)和尸检(1)被用作诊断模式.
结果：研究人群包括8名男性和1名女性。左侧吻合7例，右侧吻合2例，它位于C1/2-C2/3椎间隙的水平。在所有情况下,ECA在起源水平上比ICA大。在四个案例中，ICA的口径非常小。在一个案例中,ICA可能在出生后被阻塞，其结构与非分叉颈颈动脉（CCA）相似。除了这个闭塞的案例，在所有情况下，颈动脉分叉和EC-ICA吻合都形成了大动脉环。
结论：EC-ICA吻合术可以被视为非分叉CCA的变体，因为如果小ICA的最近段被闭塞，可能形成非分叉CCA。EC-ICA吻合位于C1/2-C2/3椎间隙之间，可能由前动脉I的残余形成。
