Minimally Invasive Computer-Assisted Approach for Cochlear Implantation

Computer-assisted navigation systems can now potentially guide the surgeon to the cochlea with a trajectory avoiding the facial nerve through a keyhole approach. Five temporal bone specimens, with 4 titanium screws placed in the mastoid cortex, were studied. Preoperative computed tomographic scan images were loaded on an electromagnetic computer-assisted surgery (CAS) system (Digipointeur, Collin, Bagneux, France). A drill was connected to the CAS to monitor its progression continuously. A conical approach passing through the facial recess and ending in the scala tympani was performed. A 0.5-mm wire was inserted into the cochlea. The keyhole approach was technically feasible in all cases. No facial nerve injury was observed on imaging and dissection control. The wire was positioned in the scala tympani and the position accuracy of the CAS was <0.76 mm on the target in all cases. The CAS system with fiducial markers yielded sufficient precision to allow a minimally invasive approach to the cochlea.