Introduction: The comparison of different surgical approaches is frequently limited by personal bias and partial or inconsistent data. This is especially evident in skull base surgery, where different complex approaches are applied to relatively rare pathologies. Quantifying surgical approaches in the anatomy laboratory should allow for their objective preclinical evaluation and comparison. We describe a relatively simple new method based on neuronavigation for the quantification of neurosurgical approaches, together with its accuracy evaluation.
Methods: The method is based on the combination of a stereotactic system with a software that elaborates the recorded coordinates, quantifying and visually rendering the "surgical pyramid of access" (Figure 1).
The method was validated in a phantom, in which four approaches were simulated (Figure 2). The approaches were quantified using a digitizer, a radiological software and the two new methods, based on a navigation system (two different systems were used) and two different softwares for coordinates elaboration (a commercially available one - Maya® - and a dedicated one).
The two new methods were then applied to the quantification of different skull base approaches in the anatomy laboratory.
Results: The reconstruction data obtained with the two navigation systems and softwares were compared with the data obtained with the digitizer and radiological software. Both methods had an accuracy comparable to the two validated methods. The dedicated software allows for a complete visual rendering of the surgical pyramid of access (Figure 3bc).
The method was applied to the quantification of different transsphenoidal approaches as well as various approaches to the anterior craniovertebral junction (Figure 3 a-c).
Conclusions: By recording coordinates with a navigation system and elaborating them with a specific software we can quantify the surgical pyramid of access. The technique has been used in the anatomy laboratory for the evaluation of skull base approaches and is even applicable in the OR setting.
Patient Care: A new method to quantify skull base approaches will provide an objective way to compare different neurosurgical approaches in the anatomy setting, therefore providing a powerful preclinical method to study new surgical approaches.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the importance of quantification of surgical access in neurosurgery
2) Discuss the new method that allows a complete quantification of surgical access
3) Provide examples of the application of the new method to skull base surgery