Anterior cerebral artery with infraoptic course – A rare anatomical variation presenting with aneurysm rupture - Literature review and an illustrative case

The infraoptic course of the pre-communicating segment of the anterior cerebral artery (ACA) is a rare malformation, occurring in 0.086 % of magnetic resonance angiography (MRA) studies. This study aims to systematically review the anatomical variation of the ACA. A case report is also included in the study. The PubMed and EMBASE databases were used for the literature search. In this study, 57 patients were identified. The unilateral infraoptic route was observed more frequently. Following the appearance of symptoms, 31 patients (54.4 %) received a diagnosis through MRA, MRI, CTA, or DSA. Out of these, 23 individuals (40.4 %) were found to have a connection with an aneurysm, and among them, 13 patients (56.5 %) exhibited aneurysmal bleeding. The patient is a 40-year-old man who presented to the emergency room with sudden, mild to moderate pain in the back of his head. After two days, the intensity of his headache progressively increased. CTA revealed a subarachnoid hemorrhage in the frontal interhemispheric area, classified as Fisher 2. The infraoptic course and the low origin of the A1 segment of the ACA are exceptionally rare conditions that might influence aneurysm development due to alterations in hemodynamic patterns. This unique setup can cause difficulties during surgery and should be well-known. This case highlights the need for thorough vascular studies before surgical planning.