Expanded Middle Fossa Approach: The Extradural Anterior Petrosectomy

Abstract

The extradural anterior petrosectomy (EAP) approach is the most direct and conservative route to reach the petroclival region. The EAP approach provides a ventrolateral trajectory to the posterior fossa through multiple corridors, requires no traction of the cerebellum, and avoid the interposition of critical neural structures between the surgeon and the target. The approach properly should be divided into four steps. The stages of the procedure are subsequently the temporopterional craniotomy reaching the floor of the middle fossa downward; gradual elevation of the dura from the temporal fossa to expose the anatomical landmarks of the rhomboid construct (delimited by the arcuate eminencia, the groove of SPS and petrous ridge, the posterior border of V3 and Meckel’s cave, and the great superficial petrosal nerve); drilling of the petrous apex within the boundaries of the Kawase triangle; and complex dura opening. The operative window offers an exposure of the ventrolateral pons from CN V as far as the origin of CN VI and basilar artery. The acoustic-facial bundle marks the posterior limit of the approach. We present here in the technique, indications and limitations of the extradural anterior petrosectomy approach. The extradural anterior petrosectomy is a reproducible and conservative lateral skull base approach to target disease processes involving Meckel’s cave, the petroclival area and the ventrolateral pons. According to the extension and behavior of the disease that need to be managed, EAP can be considered either as the unique doorway or the pivotal approach for more complex skull base routes.