A 3D Printed, Multicolor, Drillable Simulation System for Skull Base Drilling with Direct, Objective Real-Time Feedback

Background: Neurosurgical anatomy is classically learned through the combination of textbooks and atlases, intraoperative apprenticeship, and cadaveric dissection. Although laboratory dissection is potentially a very high-yield pedagogical tool, it is limited by the need for a dedicated space, access to tissue, funding, and other parameters. Correspondingly, a substantial need has emerged for alternative simulation systems that are lower-cost, less resource-intensive, and not dependent on human tissue.

Methods: Segmentation and CAD software were used to synthesize a 3D model featuring key skull base and neurovascular structures, derived from patient-specific CT and MRI imaging studies without central nervous system pathology. Following segmentation, anatomical structures were colored using multi-layered coloration. Following multicolor ColorJet 3D printing, the models were also infused with paraffin wax, to yield a more bone-like texture during drilling.

Results: The primary objective of this technical proof-of-concept analysis was to define and validate multilayered coloration patterns for key structures. In the final model, venous structures were blue superficially and purple deep. The internal carotid artery (ICA) was colored red superficially and pink deep. Facial and optic nerves were green, and the membranous labyrinth was pink, while the otic capsule bone and optic nerve sheath/falciform ligament were yellow, and the IAC was superficially colored red. Non-otic capsule bone was beige, while the dura of the cavernous sinus walls was white. Colored external layers were modeled at 0.25mm thickness; in this manner, revealing the superficial color indicated successful skeletonization, while visualization of the deep color indicated potential neurovascular injury. In the study model, features were developed to allow for the performance of numerous advanced skull base drilling procedures using a single model side. Following completion of a pterional or orbitozygomatic craniotomy, subjects could access the region of the anterior clinoid to practice a clinoidectomy, with direct feedback regarding successful optic nerve decompression (yellow visualized) without nerve injury (green visualized). Similarly, the transcavernous approach could be attempted, with the goal of entering the venous compartment (purple visualized) without injuring the nerves (green visualized) or ICA (pink visualized) contained therein. After completing a temporal-occipital craniotomy or simple mastoidectomy, subjects could proceed with decompression of the sigmoid sinus (blue visualized) without injury (purple visualized), as well as skeletonization of the labyrinth (yellow visualized) without membranous labyrinth violation (pink visualized) for a presigmoid exposure (e.g., posterior petrosectomy).

Conclusion: We report a novel, 3D-printed, multicolor, drillable simulation system for skull base drilling. The model is cost-effective and can be incorporated into skull base training curricula without the need for a facility that can prepare, store, and otherwise handle human cadaveric tissue. Additionally, a single model can be leveraged to practice at least 4 advanced skull base techniques. Although the cadaver laboratory will remain a cornerstone of neurosurgical education, we anticipate that the study model will provide an important supplemental resource for skull base trainees endeavoring to rehearse complex maneuvers in a controlled and risk-free setting.

Publication History

Article published online:
01 February 2023