Endonasal Endoscopic Approach to the Orbit (EEAO)

Objective: To describe EEAO. Methods: Three cadavers (six sides) were dissected through EEAO, exposing medial-inferior aspect of orbit. Clinical cases using same approach are subsequently presented. Results: Maxillary antrostomy-total ethmoidectomy-sphenoidotomy was performed. Maxillary sinus roof was removed to infraorbital canal laterally. Lamina papyracea was removed. Periorbita was incised along medial and inferior orbital walls. Cavernous carotid was exposed and medialized, showing oculomotor (CNIII), trochlear (CNIV), opthalmic (CNV1), maxillary (CNV2), and abducent (CNVI) nerves in cavernous sinus. Lateral opticocarotid recess was visualized with optic nerve (CNII) and opthalmic artery (OphA). Anteriorly, the annulus of Zinn was incised, showing origin of superior, medial, and inferior rectus muscles with CNIII, CN VI, CNII, and OphA. Clinically, there were eight cases of EEAO: tumor biopsy/removal (4), CNII decompression (2), aspergilloma removal (2), and hematoma drainage (1). Surgery was straightforward. Postoperative complications were convergent strabismus (2) and temporary worsening of CN III paresis (1). Cases of orbital mucocele/subperiosteal abscess were excluded. Conclusion: EEAO is a minimally invasive, relatively safe method to reach inferomedial orbital area. It exposes orbital contents up to CNII laterally and provides excellent visualization and access to the operating field. Limits of EEAO are lesions of superior and lateral parts of orbit or lesions requiring manipulation of CNII.