Computer Planning in the Research, Analysis and Design of Skull Base Surgical Approaches

Abstract

Objectives: No integrated system exists to plan skull base operations, nor to design and test new surgical approaches. Our objective was to develop a method of surgical planning, selection of optimal surgical approach(es), and design of surgical corridor geometry using a computer model that creates physical models for iterative optimization, pre-surgery approach trial, and surgical education and evaluation. Methods: The analysis was applied to a specific clinical scenario of accessing the lateral cavernous sinus. A computer analysis was performed to select the optimal surgical approach portal. Once derived, the specific geometry of the surgical corridor was designed for optimal visualization and instrumentation, while applying retraction limit constraints on specific soft tissue structures. A physical model of the surgical pathway was produced for testing, and the resultant approach was performed on 4 cadaver specimens. Results: A lateral retrocanthal transorbital approach was selected based on computer analysis. The pathway length was 55.6 mm (SD: 4.4) to 67.1 mm (SD: 0.7), retraction distance away from orbital rim was 8.2 mm (SD: 0.1), corridor volume was 2,751 mm3 (SD: 736), and cross sectional areas at the portal entrance and greater wing of sphenoid were 127 mm2 (SD: 19.2) and 210 mm2 (SD: 14.0), respectively. Dry lab and cadaver testing validated the computer planning analysis. Conclusions: A method was created and validated to determine the optimal surgical approach and pathway geometry for accessing a specific target pathology. It was robust and is applicable to many clinical scenarios. Initial evaluation in surgical cases has begun.