Congenital external carotid-internal carotid artery anastomosis: a report of three cases and literature review

Abstract

PurposeCongenital 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 ndings of this extremely rare cervical arterial variation. MethodsWe 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. ResultsThe 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 con guration 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. ConclusionEC-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.

A nonbifurcating cervical carotid artery with a remnant of the proximal internal carotid artery that mimicked an aneurysm on magnetic resonance angiography

“…On reviewing the gures of this case, we concluded that a right nonbifurcating CCA might have formed after occlusion of the ICA channel of EC-ICA anastomosis, as the caliber of the carotid artery changed abruptly at the level of the carotid bifurcation. Only nine cases of congenital EC-ICA anastomosis have been reported [11]. However, one of the nine reported cases is similar to our case [2].…”

“…The carotid bifurcation and EC-ICA anastomosis form a large arterial ring. The anastomosis is usually located at the level of the C2 vertebral body, and the ICA channel is smaller than the ECA channel [11]. If the ICA channel is not formed or occluded after development, a nonbifurcating cervical carotid artery may be formed.…”