Recognition and importance of an infraoptic anterior cerebral artery: case report

Abstract

Although variations of the anterior cerebral artery (ACA)-anterior communicating artery complex are commonly identified on imaging studies, an infraoptic course of the ACA is exceedingly rare. What is believed to be the first case of an infraoptic course of the ACA discovered with MR angiography and further characterized with conventional angiography is presented. The high prevalence of associated aneurysms and the implications for surgical planning make preoperative recognition of this anomaly critical.

Fig 1.

MR angiograms. A, Posterior oblique reformation of a 3D time-of-flight MR arteriographic data set reveals low bifurcation of the right ICA (arrowhead). Basilar tip (white arrow) and left middle cerebral artery bifurcation (black arrow) aneurysms are demonstrated. B and C, Source images from a 3D time-of-flight MR angiographic study at the level of the cavernous carotid (B) and optic chiasm (C). The right ACA (arrow) has a low origin from the ICA and ascends in a medial location between the optic nerves (arrowheads in C).

Fig 2.

Arteriograms. A–C, Frontal (A), lateral (B), and right anterior oblique (C) views from a conventional right common carotid arteriographic study demonstrate a low origin of the right ACA (black arrow), proximal to the ophthalmic artery. A small infundibulum (white arrow in A) demarcates the origin of the ophthalmic artery. The A1 segment of the ACA has a characteristic horizontal-medial course (as it passes under the ipsilateral optic nerve) before ascending to join a normally positioned AcomA. Reflux of contrast material across the patent AcomA illustrates the normal appearance of the contralateral A1 segment (arrowhead in C). The left middle cerebral artery bifurcation aneurysm (white arrow in C) is demonstrated.