Bilateral infraoptic anterior cerebral artery associated with de novo aneurysm formation over a 10-year period: illustrative case.

BACKGROUND: The infraoptic origin of the anterior cerebral artery (ACA) is a rare anatomical variant with implications for endovascular and microsurgical intervention. To date, there have been approximately 55 reported cases in the literature. Of these, only 20 are bilateral. The authors present the case of a 55-year-old female with bilateral infraoptic origin of the ACA with an associated aneurysm that developed over the course of 10 years. OBSERVATIONS: On cerebral angiography, the bilateral ACAs originated from the cavernous/ophthalmic segment of the internal cerebral artery. The A1 segment was hypoplastic on both sides. The right infraoptic ACA was associated with an aneurysm, while the left had an infundibulum. LESSONS: Patients with infraoptic ACA may be at risk for developing aneurysms de novo due to turbulent flow from the morphological changes to the vessel and therefore should be considered for interval follow-up with serial imaging. Additionally, preoperative recognition of this variant is critical in order to understand the aberrant anatomy and avoid any inadvertent vascular complications. https://thejns.org/doi/10.3171/CASE25676.