Quantitative Assessment of Operative Fields of Minimal-Invasive Approaches to the Anterior Fossa

Objective: The aim of this study is to compare minimal-invasive keyhole craniotomies that allow access to anterior fossa to the gold standard, the pterional craniotomy through cadaveric dissection. Methods: Supraorbital, lateral supraorbital, minipterional, and pterional craniotomies were performed in four cadaveric heads. All specimens underwent a CT scan using soft and bone tissue slices. For each craniotomy, superficial and deep surface reference points and points of operative interest were obtained by means of a navigation tool. Offline, respective superficial and deep surfaces and corresponding operative field volumes were calculated and visualized via software. A score for evaluation of maneuverability was defined for surgical points of interest. Results: The dissections were performed, comparing the exposure afforded by each surgical route and highlighting the relationships among points of interest. Superficial surfaces, deep surfaces (cm²) and volumes (cm³) were 6.2, 20.8, 42.9 for supraorbital; 6.4, 21.9, 44.6 for lateral supraorbital; 8.1, 21.3, 45.4 for minipterional, and 17.6, 27.4, 77.4 for standard pterional craniotomies, respectively. The deep/superficial surface ratio was significantly higher for each keyhole approach when compared with pterional craniotomy (p< 0.01). Conclusion: The higher deep/superficial surface ratios of the keyhole craniotomies supply relatively higher volumes in term of surgical maneuverability when compared with pterional craniotomy.