The Anteromedial Triangle: The Risk for Cranial Nerve Ischemia at the Cavernous Sinus Lateral Wall. Anatomic Cadaveric Study

Objective: Vascular damage in the cavernous sinus can cause ischemic injury to the cranial nerves. An appropriate anatomical knowledge of the blood supply to the cranial nerves can help to reduce the morbidity associated with cavernous sinus surgery.

Material and Method: Three adult formalin-fixed and 6 cadaveric fresh heads, with common carotid arteries injected, were used for anatomical dissection in this study. A frontotemporal craniotomy, using the Dolenc technique, and an endoscopic endonasal transcavernous approach were performed, and the cavernous sinus was explored. With microsurgical dissection and photographic documentation, the anatomy of the superior orbital fissure artery in the anteromedial triangle from the lateral and medial views was demonstrated.

Results: The 12 explored cavernous sinuses demonstrated the presence of 2 principal branches directly from the intracavernous internal carotid artery that supply the cranial nerves: the inferolateral trunk and the meningohypophyseal trunk. The artery of the superior orbital fissure (SOF) originated more often from the inferolateral trunk, located in front of the sixth cranial nerve and vascularized the nn III, IV, VI, and VI at their entry in the fissure.

Conclusion: This study demonstrates that the SOF artery is a branch of the inferolateral trunk, which runs immediately under the reticularis layer at the level of the anteromedial triangle in the lateral wall of the cavernous sinus. The blood supply to all cranial nerves in the SOF is subject to injury when the lateral wall of the cavernous sinus is trespassed at the anteromedial triangle because the SOF artery runs superficially at this level. If the surgical approach to the cavernous sinus is performed using an endonasal ventral corridor, the blood supply to the cranial nerves can be completely respected by virtue of the medial-to-lateral trajectory.