Minimally Invasive Cochlear Implantation Assisted by Intraoperative CT Scan Combined to Neuronavigation

The objective of this work was to study the feasibility of minimally invasive cochlear implantation under intraoperative computerized tomography-scan coupled to navigation.

Five human resin temporal bones (two adults and three children) were used. Initially, a temporal bone imaging was obtained by the intraoperative CT-scan coupled to the navigation (O-ARM). The navigation-assisted drilling began at the mastoid surface creating a conical tunnel (4-2 mm in diameter) through the facial recess and down to the round window. A cochleostomy was performed based on the navigation. A sham electrode array was inserted in the drilled tunnel and into the cochlea.Postoperative CT-scan and dissection were performed to evaluate the trajectory, and possible injury to the external auditory canal, ossicles, or facial nerve.

The mean duration of the procedure was 24.4 ± 3.79 minutes (range, 15-35). Cochleostomy was possible in all cases without injury to other structures. The sham array was inside the cochlea in all cases. The mean distance between the drilled canal and the mastoid portion of the facial nerve was 1.2 ± 0.07 mm (range, 1.08-1.38). The mean tracking error was 0.6 ± 0.26 mm (range, 0.20-0.72) at the entry point, 0.6 ± 0.33 mm (range, 0.2-1.02) at the facial nerve and 0.4 ± 0.07 mm (range, 0.36-0.51) at the cochleostomy.

Cochlear implantation through a minimally invasive approach assisted by intraoperative imaging combined with navigation was feasible in operating room environment and experimental conditions.