Which Routes for Petroclival Tumors? An Anatomic Comparison between the Anterior Petrosectomy and the Expanded Endoscopic Endonasal Approach

Objective: Because of their critical neurovascular relationships, petroclival tumors remain a surgical challenge. The recent development of endonasal expanded approaches (EEEA) to the skull base raised the question of rationale for classical anterior petrosectomy (AP). Herein, we present a cadaveric anatomic comparison between the AP and the EEEA. Material and Methods: Five fresh cadaveric heads were harvested and injected with colored latex. A comparison of the anatomical exposure obtained for each approach was performed. Results: The AP offers a narrow direct superolateral access to the petroclival area. Using this corridor, the cavernous sinus, the retrochiasmatic region, and the perimesencephalic cisterns are accessible. However, the working space is crossed by the trigeminal nerve. Moreover, tumor extensions toward the jugular foramen, inside the clivus, or behind the internal acoustic meatus are hardly controlled. Several corridors to the petrous apex can be described for the EEEA: a medial transclival approach, an inferior transpterygoid approach and a lateral approach through the Meckel cave. All these allowed an easy access to the clivus but the petrous apex behind the ICA is hardly exposed as well as tumor extensions to the perforating posterior space or behind the internal acoustic meatus. Conclusion: The PA should be preferred for petrous apex intradural tumors (meningiomas) and the EEEA for extradural midline tumors (chordoma) or cysts to drain.