Software-enabled CT analysis of optic nerve position and paranasal sinus pneumatization patterns

OBJECTIVE., Delineate the relationships among the optic nerve (CN 11), the sphenoid sinus, and the sphenoethmoid cell. STUDY DESIGN. High-resolution CT scans of 64 frozen human cadavers were obtained on a Siemens VolumeZoom CT scanner (Munich, Germany) and transferred to a CBYON Suite Doctor Station version 2.6 (CBYON, Mountain View CA) for standardized review. RESULTS. Pneurnatization around CN 11 was categorized into 5 types: no adjacent pneumatization (type 0), pneumatization adjacent to CN II (type 1), adjacent pneumatization with indentation (type 2), pneumatization of <50% CN 11 circumference (type 3), and pneumatization of > 50% CN 11 circumference (type 4). The prevalence of types 0 to 4 CN 11 position relative to the sphenoid sinus was 4.7%, 25.8%, 39.8%, 14.1%, and 15.6%, respectively. The prevalence of sphenoethmold cells was 28.1%. The prevalences of types 0, 1, 2, 3, and 4 CN 11 positions relative to the sphenoethmoid cell was 5.6%,58.3%, 25%, 2.8%, and 8.3% respectively. CONCLUSIONS: Software-enabled CT review facilitated precise study of the anatomic relationships of CN II. Caution must be exercised during sinonasal surgery to minimize the risk of inadvertent CN 11 injury.