The Effect of a Bone Groove Against Cochlear Implant Electrode Migration.

HYPOTHESIS: The risk of electrode migration in cochlear implant (CI) surgery can be reduced by securing the electrode lead in a bone groove in the chorda-facial angle.

BACKGROUND

Electrode migration is an important complication in CI surgery, which affects hearing performance, may induce pain and facial nerve stimulation, and requires surgical revision. A potential method to secure the electrode is to use a bone groove created in the facial recess to fixate the electrode lead. This surgical measure is a standard procedure for lateral wall electrodes (LWE) in our clinic since 2013.

METHODS

Retrospective analysis of consecutive CI cases of a tertiary referral center from 2006 to 2016 and comparison of incidence rates between group A (without bone groove, years 2006-2012) and group B (with bone groove fixation, years 2013-2016). Clinical cases were reviewed with respect to electrode type, migration length, time interval to migration, and findings during revision surgery.

RESULTS

Seventeen cases of electrode migration were found in a total of 1,603 cochlear implantations. Only LWE designs were affected by migration. The cumulative incidence for LWE in group B (0.5%) was significantly lower than in group A (3.7%, p < 0.01). The two migration cases in group B revealed insufficient geometric design of the bone grooves. Only one patient experienced a remigration after revision surgery.

CONCLUSION

The fixation in a bone groove in the chorda-facial angle is an effective measure against migration of LWE. Proper surgical execution is mandatory to ensure a tight and enduring fit.