Anatomical Landmarks and Boundaries of the Endoscopic Sublabial Transmaxillary Approach to the Middle Cranial Fossa: A Cadaveric Study.

AIM: To demonstrate the anatomical framework of the endoscopic sublabial transmaxillary approach (ESTA) to the middle cranial fossa (MCF). MATERIAL and METHODS: Six formalin-fixed human cadaveric heads injected with red and blue silicone were used for endoscopic dissections to define the surgical landmarks and anatomical limits of the ESTA. Images were obtained using a 4K high-definition camera, microscope, and video endoscopy systems. RESULTS: Accessing the MCF via the ESTA involves sublabial mucosal dissection; drilling of the anterior wall of the maxillary sinus; removal of the maxillary sinus mucosa while preserving the infraorbital nerve (ION); opening of the posterior wall of the maxillary sinus, with the ION serving as the medial limit; drilling of the lateral pterygoid process; mobilization and retraction of the superior head of the lateral pterygoid muscle and the temporalis muscle; identification of the foramen rotundum (FR) and foramen ovale (FO), followed by the maxillary and mandibular nerves; drilling of the sphenoid bone, limited medially by the vertical line extending from the FR and inferiorly by the horizontal line extending from the FR; and entry into the temporal pole following dural opening. The ESTA provided a statistically significantly shorter distance to the MCF than the endonasal transmaxillary approach (EETA, p < 0.001). CONCLUSION: The MCF can be accessed through the ESTA while preserving the surrounding neurovascular structures. This approach provides direct access to the temporal pole without the need for craniotomy or brain parenchymal retraction and may serve as an alternative to conventional transcranial approaches.