Anatomical and Imaging Studies of Endoscopic Optic Nerve Decom- pression

Objective: To provide rationale for the clinical application of endoscopic optic nerve decompression based on anatomical and imaging studies. Methods: The anatomy of optic nerve canal and its adjacent structures of 20 facial sides of human cadaver heads were examined by multislice spiral CT scanning and imaging workstations. Anatomical and imaging measurements were compared. Results: The following types of optic nerve canal were found: canal, 5% (1 facial side); semicanal, 10% (2 facial sides); impression, 55% (11 facial sides); non-impression, 30% (6 facial sides). The relationships of the sinuses to the optic nerve canal and its adjacent structures are as follows: ethmoidal, 15% (3 facial sides), sphenoidal, 35% (7 facial sides), ethmoid-sphenoidal, 45% (9 facial sides); sella turcica, 5% (1 facial side). The ophthalmic artery is interior inferior to the optic nerve at the intracranial interior opening of the optic nerve canal (80%, 16 facial sides) and lateral inferior at the orbital aperture of the optic nerve canal (85%, 17 facial sides). 70% (14 facial sides) showed carotid canal protruding at the outer wall of the sphenoid sinus, while 95% (19 facial sides) resided with the optic nerve in the optic nerve canal recess. The length of the optic nerve canal interior wall measured (10.23 ± 1.31) mm. The distances and angles of the orbital aperture, intracranial interior opening, optic nerve, and internal carotid artery recess to the junction of the nasal columella and pinna were measure by anatomical and imaging methods. The differences in measurements between the methods were not statistically significant (p > 0.05). Conclusions: This study provides anatomical parameters for endoscopic optic nerve decompression. The use of a CT imaging workstation can facilitate accurate identification and measurements of anatomical landmarks of the optic nerve.