Expanded Endonasal Approach to the Intraconal Orbit: A Comparative Anatomic Study with and without External Rectus Muscle Displacement

• Main Authors: Rawal, Rounak B., Overton, Lewis J., Rodriguez, Ana L., Farzal, Zainab, Sasaki-Adams, Deanna, Ewend, Matthew, Ebert, Charles S., Senior, Brent A., Zanation, Adam M.
• Format: Conference Proceeding
• Language: English
• ISSN: 2193-6331; 2193-634X
• DOI: 10.1055/s-0035-1546649

Background: The expanded endonasal approach (EEA) has previously been described to access the medial orbit for a variety of pathology; however, intraconal approaches are still novel and evolving. Here, we study inferior rectus and medial rectus displacement via an external approach and the degree of endoscopic access it allows on fresh human cadaveric specimens. Study Design: This is a comparative anatomic study on fresh human cadavers. Methods: Endoscopic approaches to the medial and intraconal orbit were performed. Measurements of anterior and medial rectus corridors of the AEA and PEA and extent of optic nerve visualization were performed. Vessel loops were then externally introduced into the sites of medial rectus and inferior rectus attachment to the globe and displaced by an assistant. Inter-rectus distances were then remeasured. Paired Student t -tests were used to compare measurements. Results: A total of four human cadavers were dissected bilaterally ( n  = 8). Mean medial rectus length and standard deviation were 17 ± 0.27 mm. Mean optic nerve length and standard deviation were 8.6 ± 0.25 mm. Mean caudal–rostral distance and standard deviation between medial and inferior rectus at the level of the AEA and PEA were 3.5 ± 0.8 and 1.3 ± 0.3 mm ( p