Infraoptic course of the anterior cerebral artery: case report

An infraoptic anterior cerebral artery (ACA) arising at a low bifurcation of the internal carotid artery is a rare anomaly, of which about 33 cases have been reported to date, often in association with cerebral aneurysms. We describe a case involving an infraoptic ACA in which a ruptured middle cerebral artery aneurysm was also present. Angiography revealed the presence of an abnormal solitary ACA, arising from the intracranial proximal internal carotid artery near the origin of the ophthalmic artery, and a contralateral middle cerebral artery aneurysm. Magnetic resonance imaging showed that the ACA passed below the ipsilateral optic nerve, anterior to the optic chiasm, to join the normally positioned anterior communicating artery above the optic chiasm