• Viola Bartoletti, Nicolo Norri, Ivan El-Sayed, Adib A Abla, and Rodriguez RubioRobertoRSkull Base and Cerebrovascular Laboratory, University of California, San Francisco, California, USA; Department of Neurological Surgery, University of California, San Francisco, California, USA; Department of Otolaryngology-Head and.
• Neurosurgery, Department of Neuroscience, University of Padua, Padua, Italy; Skull Base and Cerebrovascular Laboratory, University of California, San Francisco, California, USA.
• World Neurosurg. 2023 Oct 1; 178: e79e95e79-e95.

BackgroundDespite growing interest in the endoscopic endonasal approach (EEA) to the medial orbital apex (OA), a comprehensive description of the multilayer topology lying at the intersection of the regional compartments is missing.MethodsAn EEA to the OA, pterygopalatine fossa, and cavernous sinus was performed in 20 specimens. A 360° layer-by-layer dissection was performed taking into consideration relevant anatomical aspects of the interface and documented with 3-dimensional technologies. Endoscopic landmarks were analyzed to provide an outline of the compartments and identify critical structures. Additionally, the consistency of a previously described reference called orbital apex convergence prominence was analyzed and a method to identify its position was introduced.ResultsThe orbital apex convergence prominence was an inconsistent finding (15%). However, a craniometric method introduced in this study proved to be reliable to reach the orbital apex convergence point. Additional structures such as the sphenoethmoidal suture and a 3-suture junction (sphenoethmoidal-palatoethmoidal-palatosphenoidal) helped to identify the posterior limit of the OA and define a keyhole to access the compartments of the interface. We defined the bone limits of the "optic risk zone," an area where the optic nerve is more susceptible to damage. Furthermore, an orbital fusion line (periorbita-dura-periosteum) was identified and divided into 4 segments according to adjacent structures: optic, cavernous, pterygopalatine, and infraorbital.ConclusionsUnderstanding cranial landmarks and the folds of the layers covering the orbito-cavernous-pterygopalatine interface can facilitate tailoring an EEA to the medial orbital space and avoid unnecessary exposure of sensitive anatomy in the vicinity.Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.

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