A New Bony Anatomical Landmark for Lateral Skull Base Surgery

Background and Objective: The aim of the study was to propose a new bony landmark, point O, which is the junction point of the temporosphenoid suture and the infratemporal ridge; this landmark may improve the identification and preservation of neurovascular structures when approaches are used to access the middle cranial fossa in lateral skull base tumor surgeries. Methods: Fifteen cadaveric heads were measured for anatomical analysis. Related surgical landmarks were studied using the Destroscope virtual reality system and during the dissection procedures, and the results were analyzed and compared. Results: From the perspective of the middle skull base, the radial lines from point O to the interior point of the superior orbital fissure, foramen rotundum, foramen ovale, and foramen spinosum are approximately equal in length, with an average length of 23.22 mm, and the above 5 points form a sector with an angle of 66.07 degrees and an area of 310.71 mm(2). Conclusions: Identification of point O as a landmark for lateral skull base surgery when other landmarks are not recognizable optimizes patient safety and surgeon confidence during complicated operations. The interior points of the superior orbital fissure, foramen rotundum, foramen ovale, and foramen spinosum are distributed on the arc of a circle whose center is point O. The sector formed by the above 5 points is not only a crucial area for the communication of lesions between the middle skull base and the infratemporal fossa but also a safe avenue through which to remove skull base lesions.