Three dimensional images of microsurgical anatomy for a transpetrosal approach *
A transpetrosal approach can provide neurosurgeons with excellent exposure of lesions of the clivus and the anterolateral portion of the brain stem, because they can be approached perpendicularly with a short working distance, various angles for dissection are available, and minimal retraction of the temporal lobe and cerebellum is necessary. The operative procedure through this approach, however, is an extremely difficult one, because the petrous bone is anatomically complicated and maximized drilling is needed. Ten cadavers were dissected under an operative microscope and the problems involved in safe drilling of the petrous bone were examined. The anatomical milestones, which are usually used during this procedure, were not necessarily reliable. Selective three dimensional images of the petrous bone involving such important structures as the facial nerve, semicircular canals, cochlea, vestibular aqueduct, sigmoid sinus and internal carotid artery were made using the workstation（Advantage Windows）. These three dimensional images were very accurate and could be used as a preoperative simulation, which was useful for preserving important structures. They were also applied to a navigation system during a posterior petrosectomy. This method was also extremely useful when drilling into the petrous bone as rapidly and safely as possible. (Accepted on September 21，2004)
