Infraoptic anterior cerebral artery: case series report and literature review.

An infraoptic course of the precommunicating anterior cerebral artery (A1 segment) is a rare anomaly. We report three patients with an infraoptic A1 diagnosed by computed tomography angiography and we review the literature focusing on embryological development. In all three patients, a left infraoptic A1 that originated from the ophthalmic level of the internal carotid artery was diagnosed incidentally. Only one patient had a normal supraoptic A1. The embryogenesis of this anomaly is unclear. We propose that an error in the development of the definitive ophthalmic artery is possible mechanisms giving rise to this anomaly.