Figure 1.

(A) Patient position for the retrolabyrinthine approach (left-sided approach). The inion (1), mastoid process (2), zygomatic arch (3), external auditory meatus (4), superior nuchal line (5), and linea temporalis (supramastoid crest) (6), all of which may be palpated before the skin incision, are illustrated. (B) The mastoid surface after elevation of the scalp. External landmarks, which define the extent of retrolabyrinthine bone removal, are visualized, including the posterior rim of the external auditory meatus (1), mastoid tip (2), asterion (3), linea temporalis (4), spine of Henle (5), and the cribrose area (6). (C) After the mastoidectomy and before the dura is opened, the sigmoid sinus is completely skeletonized, the lateral bony labyrinth and fallopian canal are visualized, and the dura of the presigmoid, middle fossa, and posterior fossa are exposed. (D) View of the cerebellopontine angle with the VII–VIII cranial nerve complex emerging from the lateral pontomedullary junction as seen through the retrolabyrinthine exposure. The anterior inferior cerebellar artery can be seen looping near this complex. The trigeminal nerve, choroid plexus, and IX–X cranial nerve complex are also visible with this approach.