Proximal Branches of the Anterior Cerebral Artery: Anatomical Study and Applications to Endoscopic Endonasal Surgery

Background The anatomical relationship between the anterior cerebral artery (ACA) and suprasellar suprachiasmatic lesions is especially relevant, as large anterior fossa meningiomas might encase the ACA and its proximal branches. The endoscopic endonasal approach (EEA) is an alternative for anterior skull base tumors, but vascular encasement is a relative contraindication. A detailed understanding of the surgical anatomy of the ACA branches and their variations from an endonasal perspective becomes essential for avoiding vascular complications and improving surgical resectability. The aim of this study was to evaluate, from an endonasal perspective, the anatomical variations of the ACA and its proximal branches, in particular the recurrent artery of Heubner (RAH), the fronto-orbital (FOA) and the frontopolar (FPA) arteries.

Methods The origin, course, branching pattern, diameter, and relationship of the proximal ACA branches with the optic apparatus and the olfactory tract were studied in 25 head specimens (50 sides). Three distinct skull base lesions involving the ACA branches were selected to illustrate the surgical application of the findings.

Results The RAH was present in all hemispheres and originated within 3.1 ± 1.5 mm of the anterior communicating artery (AcomA; either proximal or distal to it). We found more than one RAH in 68% cases (1.9 branches average, range: 1–4), with a mean diameter of 0.44 ± 0.17 mm. Regardless of its origin, its course was parallel to the ipsilateral A1. Based on the spatial relation of the RAH and the A1 segment, we observed three types of RAH courses: anterior (40%), posterior (38%), and superior (22%). The FOA was present in all cases and arose mainly from the A2 segment (70%) with a mean distance of 5.92 ± 4.1 mm from the AcomA. We found more than one artery in 48% cases (1.6 branches average, range: 1–3), with a mean diameter of 0.7 ± 0.46 mm. The FOA initially ran along the gyrus rectus and typically entered the olfactory sulcus and crossed the olfactory tract to reach the medial orbital gyrus. Based on its relation with the olfactory tract, we described three types of FOA courses: in 54% the FOAs crossed its proximal third, in 31% its middle third, and in 15% did not cross the olfactory tract running parallel to it along the gyrus rectus, and it provided terminal branches to the olfactory tract and bulb. The FPA was present in 92% of hemispheres and it always arose from the A2 segment, with a mean distance of 10.7 ± 5 mm from the AcomA. It coursed anteriorly within the interhemispheric fissure toward the frontal pole, and never crossed the olfactory tract.

Conclusion The RAH, FOA, and FPA can be differentiated according to their origin, course, and final destination. The key landmarks for these three arteries are the A1 segment, the olfactory tract, and the interhemispheric fissure, respectively. A detailed knowledge of the surgical anatomy of the proximal ACA branches from a ventral perspective is essential for performing successful and safe endonasal surgery in the suprasellar suprachiasmatic region.