Target error evaluation of a minimal invasive cochlear implant strategy using a patient specific miniature stereotactical frame.

Minimally invasive cochlear implant surgeries require a very high accuracy of at least 0.5 mm when drilling a canal through the most critical spot, the facial recess [1]. Important anatomical structures in the vicinity of the minimal invasive access path, including the facial nerve and the chorda tympani must be preserved. We conducted a quantitative verification study on five temporal bone specimens using the patient specific miniature stereotactical frame called „Microtable“. The Microtable is developed at Vanderbilt University (Nashville, TN) and evaluated in a multi center study together with the Medical School Hannover (MHH). After classical mastoidectomy and opening of the facial recess we measured the target error at the facial recess in an extra „post-OP“ CBCT (Cone Beam Computed Tomography) scan with a sham drill bit inserted.