Clinical evaluation of the SmartNav system contribution in cochlear implantation surgery

To evaluate the contribution of electrode insertion live monitoring, offered by the Nucleus® SmartNav system, in cochlear implantation surgery since correct and precise electrode placement can assure better preservation of the cochlear structure.

A prospective cohort study was conducted on 66 patients, with normal cochlear anatomy, operated for unilateral cochlear implantation. Once the surgeon started inserting the electrodes under SmartNav monitoring, the progression of the electrode array and its position were assessed, and the angular insertion depth, placement time and speed of insertion were measured.

The mean insertion speed was 0.49 mm/s, which corresponds to a total insertion time of 40.81 s for the used CI522 electrode. The benefit of training was highlighted by comparing the mean values of insertion speed between the initial half of procedures and the final half performed by the same surgeon, indicating a reduction of 0.10 mm/s (20%). The mean angular insertion depth was 401.71° (251-572), while, when compared with the preoperative CT scan measures of the cochlear diameter, only a moderately negative correlation was found (r = - 0.51). Also, two cases of Tip Fold-over were detected with immediate correct replacement of the electrode.

Cochlear implantation with live monitoring by the SmartNav system offers the main advantage of controlling the surgeon's insertion speed, which he can modulate to achieve the softest atraumatic insertion, with a positive training effect resulting in reduced speed over time. Additionally, it demonstrated its effectiveness in detecting tip fold-overs in a safer way than radiologic imaging.