Right non-bifurcating cervical carotid artery with a long-segment incomplete carotid bifurcation, a right accessory middle cerebral artery arising from a common trunk with a cortical branch at the distal A1 segment.

introductionBoth non-bifurcating cervical carotid artery (NBCA) and accessory middle cerebral artery (aMCA) have been reported previously. Here, we report a rare case of right NBCA with a long-segment incomplete carotid bifurcation, associated with a right aMCA arising from a common trunk with a cortical branch at the distal A1 segment.

methodsThe patient was a 70-year-old woman who was transferred to our department from another hospital for further evaluation and treatment after an anterior communicating artery aneurysm had been identified. No obvious neurological abnormalities were found on admission. Whole-brain angiography was performed via right transradial access. Contrast medium was selectively injected into the bilateral common carotid arteries and bilateral vertebral arteries.

resultsCerebral angiography demonstrated an anterior communicating artery aneurysm, left subclavian artery stenosis, and basilar artery stenosis. In addition, multiple cerebrovascular variants were identified. On the right side, the NBCA gave rise to proximal branches of the external carotid artery (ECA) and continued distally as the internal carotid artery (ICA), with a fenestration-like configuration caused by a long-segment incomplete carotid bifurcation. The distal right A1 segment gave rise to an anomalous common trunk, which further divided into an AMCA and a cortical branch. Vascular measurements showed that the main limb of the fenestration-like structure was 32.49 mm in length with an average diameter of approximately 4.56 mm, whereas the side limb was 32.23 mm in length with an average diameter of 2.68 mm. After comprehensive risk assessment, only left subclavian artery stenting was performed during this hospitalization. The patient recovered well after the procedure, with no new neurological deficits at discharge. Follow-up DSA at 1 month demonstrated stent patency, and no new cerebrovascular events occurred during follow-up.

conclusionWe report an extremely rare case of multiple coexisting cerebrovascular variants involving the right carotid system, including an atypical right NBCA with a long-segment incomplete carotid bifurcation and a right aMCA arising from a common trunk with a cortical branch at the distal A1 segment. These atypical variants may provide additional insight into the developmental mechanisms of NBCA and aMCA and help further expand current understanding of cerebrovascular development and anatomy.