Computer-aided surgery in the petrous bone

Objectives: We demonstrate that computer-assisted frameless stereotactic na vigation with the ISG/ELEKTA Viewing Wand system in the petrous bone is rou tinely possible with sufficient application accuracy. Methods: High-resolut ion computed tomography imaging is done with a dedicated structure attached to the mouthpiece of the Vogele-Bale-Hohner (VBH) head holder, an integral part of our intraoperative patient fixation, The patient image registratio n can be reliably performed before surgery in an unsterile environment with the registration structure of the mouthpiece. For intraoperative navigatio n either the position-sensitive articulated arm or the optical three-dimens ional digitizer of the ISG/ELEKTA system is used. Results: In the operation s of the petrous bone performed so far, i.e., mastoidectomy, cholesteatoma surgery, and lateral skull base revision surgery, the clinical value of thr ee-dimensional navigation was clearly demonstrated with an application accu racy, constant throughout surgery, mostly limited only by the resolution of the computed tomography.