Endoscopic Transnasal Transmaxillary Approach to Orbital Apex through the Meningo-Orbital Band: A Cadaveric Feasibility Study

Extradural transcranial release of the meningo-orbital band occupying the lateral part of the superior orbital fissure is used to approach the orbital apex and middle cranial fossa. The authors tested the feasibility of the release of the meningo-orbital band via an endonasal transmaxillary approach.Five injected cadaveric heads were assessed for dimensions of superior orbital fissure by computerized tomography. An endonasal transsphenoid transpterygoid approach was done to the superior orbital fissure and annulus of Zinn medially, down to the maxillary nerve. The periorbita was dissected superolaterally to expose the greater wing of the sphenoid and the meningo-orbital band. The superior orbital fissure was decompressed inferiorly by drilling the greater wing of the sphenoid and the maxillary strut after transposition of the maxillary nerve. The meningoorbital band was cut at the junction of the lateral part of the superior orbital fissure and the periorbita exposing the frontotemporal dural junction. The edge of the lesser wing of the sphenoid was drilled toward the annulus of Zinn and the optic canal. The temporal lobe dura was separated from the periorbita and lateral cavernous dural wall at the meningo-orbital band and the ophthalmic nerve.The superior orbital fissure had an oblique angle (mean: 39 ± 2.75 degrees) to the midsagittal plane, the length of its lateral part corresponding to the meningo-orbital band was (mean: 6.08 ± 2.58 mm) and the distance from its lateral end to midline was (mean 2.97 ± 0.11 cm). The meningo-orbital band was released in 10 cadaveric head sides with a distinct plane between the periorbita and the dura propria. Transmaxillary endoscopy provided less orbital retraction and better visualization of the lateral wall of the cavernous sinus.Endonasal transmaxillary release of the meningoorbital band is feasible, allowing exposure of the orbital apex and the middle cranial fossa.