Transpalpebral transorbital endoscopic lateral approach to the middle cranial fossa: anatomical study in cadaver

Transorbital expanded endoscopic approaches allow different areas of the skull base to be approached. The aim of our study is to analyse the main anatomical bone and neurovascular structures of the middle cranial fossa by means of a transpalpebral transorbital lateral endoscopic approach (TTLEA). An anatomical study was performed on 12 orbital cavities corresponding to 6 cadaver heads. All specimens were previously injected with colored latex through both carotid systems. The mean distance from the orbital rim to the zygomatic-facial foramen and to the zygomatic-temporal foramen was 11 mm and 16 mm respectively. In all cases the meningo-orbital foramen was found at a mean distance from the orbital rim of 34 mm. The superior orbital fissure (SOF) was located posterior to the meningo-orbital foramen at 39 mm. The foramen rotundum and foramen ovale were located separated from each other by 10 mm on average. Anterior to the foramen ovale a bony prominence was observed in all cases. In 11 cases (92%) the entrance of the accessory meningeal artery into the foramen ovale was evident and in one case an accessory foramen was observed. The middle meningeal artery was located in all dissections within the foramen spinosum. The TTLEA offers a wide and direct exposure of the middle cranial fossa. It should be considered as an alternative to transcranial approaches in certain lesions invading the lateral region of the middle cranial fossa, the lateral wall of the cavernous sinus or the infratemporal fossa.