Radiologic detectability of the cochlear implant electrode fixation clip using cone beam computed tomography

With the aim of preventing migration of cochlear implantation electrodes in the postoperative course, an electrode fixation clip has been developed. It is characterized by two clips of double U-geometry. The bone fixation clip will be clamped on the bony incus bridge, and the electrode fixation clip is clamped to the electrode lead. Although made of titanium, the detectability in radiologic imaging appears limited.

Six patients, who received a cochlear implant between August 2014 and March 2015, were retrospectively analyzed for the detectability of the Med-El Electrode Fixation Clip in postoperative cone beam CT scans. For these patients, we randomly extracted appropriate control group patients without implanted clips (matched pairs). One instructed neuro-radiologist blindly evaluated postoperative radiographs on a visual, descriptive basis of both groups with the main outcome measure of clip detectability.

In total, images of 12 patients were evaluated. In five of the six (83%) study group patients, the clip was detected radiologically correct. One patient (17%) was appointed as false negative. All patients (100%) without a clip were correctly identified.

The electrode fixation clip can be identified, despite its small size, using cone beam CT. Sensitivity and specificity are high. This aspect assumes importance especially in postoperative monitoring, e.g. in cases of revision surgery. Thus, this study contributes to the overall safety in cochlear implant surgery.