[Lateral endoscopic transorbital approach to middle skull base: anatomical and surgical practice study]

Objective: To investigate the anatomical and surgical approaches to middle cranial fossa through orbital lateral wall under endoscope. Methods: Cadaveric formalin fixed specimens and fresh colored silicone injected specimens were used for this study. All anatomic technical measurements were performed under 0° and 30° endoscope and infrared rays navigation. The surgical approach was designed with the bony opening on the lateral wall of orbit through which the lateral side of the middle cranial fossa could be directly entered under endoscope. One case of recurrent meningioma was performed through this surgical approach. SPSS 20.0 software was used for statistical analysis. Results: The approach can directly enter the middle cranial fossa and expose anatomic landmarks including superior orbital fissure, lateral side of cavernous sinus, foramen rotundum, foramen ovale, foramen spinosum, petrosal bone and others as well as Ⅱ, Ⅲ, Ⅳ, Ⅴ, Ⅵ cranial nerves under endoscope. The maximal bony opening through the lateral wall of orbit was measured, with a horizontal diameter of (1.38±0.68) cm, a vertical diameter of (2.02±0.32) cm, a depth of (1.44±0.42) cm from bony opening margin to the dura. The recurrent meningioma involving lateral side of the middle skull base was successfully removed by this surgical approach through lateral wall of orbit. Conclusion: Lateral transorbital endoscopic approach to the lateral side of middle skull base is a safe, feasible, and minimally invasive method, which allows surgeons to directly manipulate diseases involving this area with good visualization and minimal invasion under endoscope.