J Neurol Surg B Skull Base 2013; 74 - A247
DOI: 10.1055/s-0033-1336370

Endoscopic Endonasal Anatomy of the Optic Canal

Francisco A. Vaz Guimaraes Filho 1(presenter), Omar Ramirez 1, Yancy Acosta 1, Luis R. Bonilla 1, Milton M. Rastelli Jr.1, Maria Koutourousiou 1, Juan C. Fernandez-Miranda 1, Paul A. Gardner 1, Carl H. Snyderman 1
  • 1Pittsburgh, PA, USA

Objective: The endoscopic endonasal approach to the optic canal (OC) may be done for many purposes. However, there is no known published paper that describes the anatomical details of the region through an endoscopic endonasal perspective. The aim of this study is to fill this gap.

Materials and Methods: Ten heads (20 OCs) were prepared for dissection at the Surgical Neuroanatomy Laboratory of the University of Pittsburgh Medical Center. The topographic relationships between relevant structures and pertinent measurements were evaluated.

Results: The optic nerve, carotid prominences, and optic-carotid recesses (OCRs) were observed in all specimens. The length of the falciform ligament was 1.70 mm ± 0.47 mm. The OC started in the medial OCR about 0.65 mm ± 0.75 mm from the medial point of the lateral OCR. The OC ended 0.40 mm ± 0.50 mm from the external part of the lateral OCR, closer to the orbital apex. The length of the OC was 6.05 mm ± 0.724 mm. The ophthalmic artery (OA) originated from the supraclinoid segment of the carotid in all cases approximately 2.50 mm ± 1.23 mm from the medial OCR. In four cases (20%), it was found 1 mm or less anterior to the optic canal’s intracranial foramen. In 16 (80%), the OA was inferomedial to the optic nerve, inferolateral in 3 (15%), and lateral in 1 case (5%).

Conclusions: The medial and lateral OCRs are the most important landmarks to determine the location of the OC. Caution should be taken when opening the dura because of its intimate relationship with the optic nerve and the variable course of the OA.