Endoscopic endonasal transsphenoidal approach for decompression of optic nerve: an anatomic study

Objective: To explore the endoscopic surgical anatomy of optic canal and establish an anatomic basis for endoscopic optic nerve decompression. Methods: Eight adult cadaveric heads were studied under endoscopes. The endoscopic endonasal transsphenoidal approach was simulated, and the paraseptal, middle meatal, or middle turbinectomy approach was used separately to observe the lateral wall and posterior wall of sphenoidal sinus. Through an anterior sphenoidotomy, the posterior wall, the lateral wall, the superior wall and the floor of the sphenoidal sinus were exposed after removing the mucosa and septa. The posterior wall and posterior-lateral wall were opened and the optic canal and surrounding structures were dissected layer by layer. Results: The optic-carotico recess was permanent anatomic landmarks comparatively within the landmarks on the posterior wall of the sphenoidal sinus, as well as the exclusively consistent bony landmark in the optic region. The optic-carotico recess, which was bordered by optic nerve, cavernous sinus, internal carotid artery in the cavernous sinus, ophthalmic artery and oculomotor nerve, was the demarcation between the canalicular segment and intracranial segment of optic nerve. The connecting line between bilateral carotico-optic recess was the projection of tuberculum sellae. Conclusions: Carotico-optic recess is a very important anatomic landmark for endoscopic optic nerve decompression.