Volumetric analysis of endoscopic and traditional surgical approaches to the infratemporal fossa.

OBJECTIVES/HYPOTHESIS In an effort to decrease morbidity, skull base surgeons have explored less invasive approaches to the infratemporal fossa, including endonasal-endoscopy, minicraniotomies, and transantral endoscopic and microscopic corridors. This project presents quantitative data that assesses the practicality, and volumetric exposure afforded by endonasal and open approaches to the infratemporal fossa. STUDY DESIGN First, the study defines the anatomy of endoscopic-endonasal and preauricular approaches to the infratemporal fossa. Subsequently, the study involved the calculation of anatomical volumes using cadaveric and virtual models. METHODS Computed tomography (CT) scanning of two anatomical specimens served to recreate computer simulations of the endonasal and preauricular approaches, allowing for the assessment of the infratemporal fossae volumes. In addition, the dissections served to identify and mark critical surgical landmarks and boundaries. A second CT scan, after the surgical dissection, allowed for a reanalysis of the data for a volumetric comparison of the surgical approaches. RESULTS Pre- and postdissection CT scans and computer simulations revealed that volumes in the open and endonasal approaches to the infratemporal fossa are strikingly similar, suggesting that volumes of surgical instrumentation and visualization may also be comparable. However, the entry gate for instrumentation differed significantly for each approach. CONCLUSION This study suggests that, although the entry gate for instrumentation is greater during an open approach, contrary to intuition, an open approach does not create a substantially larger working space or visual field. Analysis of volumetric measurements facilitates a better understanding of the indications for each procedure.