Comparative Analysis of Approaches to the Infratemporal Fossa: Fisch Type-C versus Expanded Endonasal Approach

Objective: Determining the optimal approach to address lesions of the infratemporal fossa requires a thorough evaluation of the pathological process involved and its relationship to the existing anatomy, most specifically, the internal carotid artery (ICA). There are several lateral approaches to the infratemporal fossa, each of which carries its own benefits and risks. The evolution of endoscopic endonasal approaches to the skull base have allowed for both alternative and potentially complimentary approaches to this region. This study provides a comparative analysis of the benefits and anatomical limitations of the Fisch type C and endoscopic endonasal approaches to the infratemporal fossa.

Study Design: Cadaveric and radiologic study.

Methods: Both Fisch type C and endoscopic endonasal approaches to the infratemporal fossa were performed in cadaveric specimens. The exposure provided by each approach was analyzed qualitatively with the aid of high-definition photography. In addition, computed tomography volumetric analysis was performed to objectively compare both approaches.

Results: The Fisch type C approach allowed for wider access of surgical tools and a less limited surgical window while external damage is prominent and the sacrifice of critical structures is required for the approach. The endoscopic endonasal approach provided an equivalent overall surgical exposure with an ultimately complementary access to the ITF, but the entry point was more limited. The endonasal approach had less collateral damage. Practical comparison of the two approaches determined that both dissections allowed for full exposure of the infratemporal fossa and with appropriate extension of dissection, albeit from different anatomical perspectives. Volumetric analysis revealed equivalent working spaces at the target area, but the entry point was significant larger on with the Fisch type C approach.

Conclusion: The ability to manage the petrous ICA and access the infratemporal fossa through an endonasal approach is comparable to a traditional lateral approach. Adequate experience and training is required to perform endonasal procedures safely.