Electrode migration in cochlear implant patients: not an exception.

Objective: It was the aim of this study to investigate the occurrence of electrode migration of a cochlear implant in patients with and without complaints.

Methods: We performed a retrospective case review in a tertiary referral center. The electrode position was evaluated in 35 cochlear implantees, 16 with a CII HiFocus1 (non-positioner) and 19 with a HiRes90K HiFocus1J, using multiplanar reconstructions of the postoperative CT scans. Of 5 patients, a second scan was obtained to evaluate complaints of performance drop, vertigo, tinnitus, headache or nonauditory stimulation. Displacements of the electrode contacts were calculated and displacements of >1 mm were considered a migration. The possible correlation with implant type, insertion depth or presence of complaints was analyzed.

Results: Migrations were detected in 10 patients (29%). There was a significant effect of the implant type in favour of the HiFocus1, but no relation with the original insertion depth of the device. In the 5 patients scanned because of complaints, two migrations were detected.

Conclusions: In our patient population, electrode migration was not uncommon and turned out to occur in patients with and without complaints.