Comparative Anatomical Assessment of the Contralateral Precaruncular Approach to the Supraoptic Triangle : A Cadaveric Study

Abstract

Background: The supraoptic triangle (SOT) is a bony-dural region located along the superior surface of the optic canal, corresponding to the base of the anterior clinoid process. It is bounded inferiorly by the optic nerve, laterally by the upper projection of the lateral border of the lateral optico-carotid recess (LOCR), and superomedially by the planum sphenoidale. Although often targeted endonasally, this region is notoriously difficult to reach without significant manipulation of the optic nerve and internal carotid artery. Even after maximal bone removal via a transtuberculum–transplanum approach, exposure to the SOT remains limited due to its lateral and deep location. This study evaluates whether a transorbital contralateral precaruncular approach can enhance access to this region compared to standard endonasal routes. Methods: Four cadaveric heads (7 sides) were dissected. A transtuberculum–transplanum endonasal approach was performed in all specimens. Surgical access to the SOT was then assessed through three distinct routes: ipsilateral endonasal (IpsiEA), contralateral endonasal (ContraEA), and contralateral precaruncular (CPC). Quantitative metrics included working distance, fencing angle, vertical and horizontal angles of attack (AoA), surgical freedom (calculated as a percentage of the surface area of a reference sphere using a 12-point navigation model), and area of exposure (AOE). Statistical comparisons were made using paired t-tests (α = 0.05). Results: The CPC approach yielded the shortest working distance (51.3 ±8.3mm vs. 78.0 and 78.9 ± mm; p < 0.6). Conclusion: The contralateral precaruncular approach improves angular access and reduces working distance to the supraoptic triangle, supporting its use as a complementary route to reach the lateral optic canal and anterior clinoid region.