Defining the Safe Zone; the Endoscopic Sublabial Transmaxillary Approach to the Middle Cranial Fossa

Background Almost all approaches to middle cranial fossa pathologies are performed with transcranial approaches. Studies on the endoscopic approach to this region are gaining popularity over time. In this study, we aimed to demonstrate the anatomical framework of the endoscopic transmaxillary transpterygoidal approach to the middle cranial fossa (ETTAMCF). Method Six formalin fixed red and blue silicon injected human cadaveric heads were used for endoscopic dissections to define surgical landmarks and limits of the ETTAMCF. Photos were taken with 4K high-definition camera and video monitor endoscopy systems. Results To reach middle cranial fossa via ETTAMCF includes; A bucco-gingival sulcus insicion, mucosal dissection, drilling maxillary sinus anterior wall (limited superiorly with infraorbital foramen, inferiorly with buccogingival sulcus), removing mucosa of maxillary sinus while preserving infraorbital nerve, opening posterior wall of the maxillary sinus (limited medialy with infraorbital nerve), drilling pterygoid process, mobilize and retracting the upper head of lateral pterygoid muscle and temporal muscle, definition foramen rotundum and foramen ovale with following maxillary nerve and mandibular nerve, drilling sphenoid bone (limited medially with vertical line from foramen ovale inferiorly with horizontal line from foramen rotundum) and reaching temporal lobe anterior pole with opening dura mater. Conclusions Temporal lobe anterior pole is accessible safely via transmaxillary transpterygoideal approach by using endoscope while preserving neurovasculer structures. This approach provides safe access to the anterior temporal lobe without craniotomy and parenchyma retraction, as an alternative to transcranial approaches. We predict that surgery of anterior temporal lobe lesions, can be performed with this approach.