Transorbital Endoscopic Approach to the Foramen Rotundum for Infraorbital Nerve Stripping.

ABSTRACT

PURPOSE: To develop and evaluate a transorbital endoscopic approach to the foramen rotundum to excise the maxillary nerve and infraorbital nerve branch. METHODS: Cadaveric dissection study of 10 cadaver heads (20 orbits). This technique is predicated upon 1) an inferior orbital fissure release to facilitate access to the orbital apex and 2) the removal of the posterior maxillary wall to enter the pterygopalatine fossa (PPF). Angulations along the infraorbital nerve were quantified as follows the first angulation was measured between the orbitomaxillary segment within the orbital floor and the pterygopalatine segment suspended within the PPF, while the second angulation was taken between the pterygopalatine segment and maxillary nerve as it exited the foramen rotundum. With refinement of the technique, the minimum amount of posterior maxillary wall removal was quantified in the final 5 cadaver heads (10 orbits). RESULTS: The mean distance from the inferior orbital rim to the foramen rotundum was 45.55 ± 3.24 mm. The first angulation of the infraorbital nerve was 133.10 ± 16.28 degrees, and the second angulation was 124.95 ± 18.01 degrees. The minimum posterior maxillary wall removal to reach the PPF was 11.10 ± 2.56 mm (vertical) and 11.10 ± 2.08 mm (horizontal). CONCLUSIONS: The transorbital endoscopic approach to an en bloc resection of the infraorbital nerve branch up to its maxillary nerve origin provides a pathway to the PPF. This is relevant for nerve stripping in the context of perineural spread. Other applications include access to the superior portion of the PPF in selective biopsy cases or in concurrent orbital pathology.