Transorbital Approach to the Skull Base: A Construction of 3D Models Using Anatomical Dissections

Introduction: The lateral transorbital approach has been described to provide surgical access to the orbital apex, periorbital skull base, Meckel's cave, and lateral cavernous sinus.[1]–[2] However, the difficulty in visuospatial understanding of this complex region renders this technique unfamiliar for many orbital and neurosurgeons. With the popularization of three-dimensional (3D) volumetric models, new tools have arisen to enable better understanding of the spatial relationship of bony, muscular, and neurovascular structures[3] ( https://sketchfab.com/models/ab3caa90a2fb427abc9c2f59c53b8b21 ). This study presents the first stepwise, stereoscopic modeling of the lateral transorbital operative technique to access the skull base.

Methods: Anatomic dissections on two postmortem heads fixed with formalin were used to create 3D volumetric models demonstrating step-by-step the surgical anatomy of the skull base via the lateral transorbital approach. The models were created using pictures taken in 360 degrees with the 0- and 30-degree endoscopes (Stryker, Stryker Corporation, Michigan, United States). Approximately 100 to 150 pictures were obtained for each model. All images were processed to improve exposure and enhance color (DxO Optics Pro 11, DxO, France). The volumetric models were created using a photogrammetry software (Reality Capture BETA 1.0, Capturing Reality, Slovakia) and a computer graphics program (Meshmixer 3.5, Autodesk, Inc., California, United States, and Blender 2.8, Blender Foundation, Amsterdam, The Netherlands). Once complete, the models were uploaded to a web-based viewer app (Sketchfab, New York, United States) for ease of manipulation and interaction by users.

Results: Cadaveric dissections demonstrated the lateral transorbital approach to the skull base. The approach was divided into three major steps: exposure of the lateral orbital rim, take down of the lateral rim to expose the greater wing of the sphenoid bone, and removal of sphenoid bone to access the skull base. Important landmarks on the lateral wall are shown in [Fig. 1]. The thin oscillating saw is utilized to create two osteotomies, and the rim is removed with Lempert rongeur. A high-speed drill is used to remove the sphenoid bone. Through this approach, we are able to access the anterior, middle, and infratemporal cranial fossae, as well as the orbital apex ([Fig. 2]). Further dissection in the posterior bony triangle between the inferior and superior orbital fissures allows for exposure of the dura overlying the temporal lobe and, with retraction of the dura, access to the lateral cavernous sinus, petrous bone, and Meckel's cave.

Conclusion: Volumetric models are useful tool for surgeons to learn visuospatial anatomic relationships for use in education and surgical planning. The ease of use in our online platforms allows users to interact with and visualize crucial anatomy at every step of the lateral transorbital approach to the skull base in 360 degrees and virtual reality.

Fig. 1

Fig. 2

Publication History

Article published online:
12 February 2021

• References

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• 3 Kournoutas I, Vigo V, Chae R. et al. Acquisition of volumetric models of skull base anatomy using endoscopic endonasal approaches: 3D scanning of deep corridors via photogrammetry. World Neurosurg 2019; 129: 372-377