Ophthalmic Artery Arising from the Anterior Cerebral Artery and Concomitant Internal Carotid Artery Aneurysm: Report of a Case

Introduction: In 96% of subjects, the ophthalmic artery (OA) arises from the internal carotid artery (ICA). The OA and its branches make a significant contribution to the arterial supply of the retina in addition to external carotid artery branch collaterals. Other OA origins include the middle meningeal artery, the basilar artery, the posterior communicating artery and ICA bifurcation. The OA may also arise extradurally from the clinoidal segment or the intracavernous portion of the ICA and pass through the superior orbital fissure. OA originating from the anterior cerebral artery (ACA) is extremely rare. We present the unique case of a patient undergoing surgical treatment of a paraclinoidal ICA aneurysm, presenting with an OA originating from the ipsilateral ACA (A1 segment) (Fig. 1). Vascular embryogenesis and surgical anatomy are reviewed to understand this rare vascular anatomy combination.

Discussion: During embryogenesis two branches of the ICA, the primitive ventral (VOA) and dorsal ophthalmic arteries (DOA), are responsible for the vascularization of the optic cup. VOA originates from the ACA, while DOA arises from the siphon of the ICA, at the level of the inferolateral trunk. VOA and DOA anastomose around the optic nerve and both arteries show partial regression, giving rise to the primitive ophthalmic artery (POA). The adult ophthalmic arteries do not appear to come from a known precursor vessel in an expected location, since VOA and DOA involve during embryogenesis in favor of a secondarily appearing adult ophthalmic artery. In our case, the persistence of the VOA could explain the variant of the OA, which arises on the A1 segment of the ACA. Also, the anatomical position of the ICA aneurysm can be reconducted to the departure point of a migrated primitive DOA or a vestigial ophthalmic artery, at the level of the intradural segment of the ICA.

Conclusion: An abnormal origin of the OA is rare and benign in most of cases. However, this case raises the possibility of an increased risk of aneurysm formation in patients with an abnormal OA origin. This possibility should be considered in patients who are found to have an abnormal OA. Long term follow-up vascular imaging should be considered to detect de novo aneurysms.

Fig. 1 Patient undergoing surgical treatment of a paraclinoidal ICA aneurysm, presenting with an OA originating from the ipsilateral ACA (A1 segment)