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Deep Transorbital Approach to the Apex and Cavernous Sinus

Summary: Tumors of the orbital apex are difficult to approach through a standard lateral orbitotomy exposure. The transcranial approach has been described, but it requires an open craniotomy as well as dissection through the annulus of Zinn in its tight superior segment to reach intraconal and inferior lateral tumors. It is well recognized that the transcranial approach is optimal only for tumors of the superomedial orbital apex. Our study demonstrates that by enlarging the bony incision of a classic lateral orbitotomy to include a generous marginotomy and removing the deep sphenoid wing up to the superior orbital fissure, good exposure of the lateral orbital apex can be obtained. Tumors of the apex, including those that extend slightly into the cavernous sinus, can be removed from the cranial nerves and extraocular muscle origins in en face fashion, providing optimal ability to identify the delicate neurovascular structures of the orbital apex and avoid damage to them. The operating microscope is extremely useful for bony and soft tissue dissection. We report four benign tumors of the orbital apex removed using this approach. Two tumors encroached slightly into the cavernous sinus. Three of four patients were told that they had inoperable tumors. By use of the deep orbital apex approach described, all four tumors were successfully exposed and removed. Visual and motor function was unchanged or improved in all four patients, with the exception of one tumor that incorporated the inferior division of the third cranial nerve; in that patient, the transected nerve was anastomosed microscopically, and partial return of function was noted. The transorbital ophthalmic approach to tumors of the inferolateral orbital apex has significant potential advantages in comparison with a frontal craniotomy approach.