Fig. 4.

Intradural anterior petrosectomy. ( A ) The tentorium over the superior petrosal sinus has to be cut. ( B ) The dura over the petrous apex is stripped away. ( C ) The petrous apex is drilled lateral to the mandibular nerve. ( D ) The inferior border of apical petrosectomy is marked by the inferior petrosal sinus. ( E ) Anterior petrosectomy provides a more anterior and inferior exposure of the infratentorial structures. ( F ) The dura over the posterior fossa is cut to create a single opening. AICA, anterior inferior cerebellar artery; BA, basilar artery; CN, cranial nerve; ICA, internal carotid artery; PCA, posterior cerebral artery; SCA, superior cerebellar artery.