The present study reviewed a cochlear implant (CI) patient population after surgery, which received a free-fitting electrode carrier designed for hearing preservation. The aim was to determine the rate of electrode migration of the CI electrodes and present clinical and surgical implications.Study Design:
Retrospective patient review.Setting:
Tertiary referral university hospital.Patients:
Two hundred seventy-eight patients implanted uni- or bilaterally with lateral wall electrodes designed for hearing preservation (358 implants). The control group was 323 patients implanted uni- or bilaterally with preformed perimodiolar electrodes (468 implants).Interventions:
Determination of CI electrode migration was conducted according to a clinical test protocol. Revision surgery was offered in confirmed patients of electrode migration. A bone groove was considered to improve the fixation of the electrode.Main Outcome Measures:
Audiological testing including speech audiometry, subjective sound quality rating, and bilateral pitch comparison in bilateral patients, as well as radiological examinations, were conducted.Results:
Electrode migration was observed solely in patients implanted with lateral wall electrodes; 10 of 358 patients with free-fitting electrodes (2.8%) had electrode migration, which was successfully confirmed by the proposed clinical test protocol. Nine of the 10 confirmed patients underwent reinsertion surgery. Mean perception score decreased from 75.0% to 62.1% after electrode migration and recovered completely after reinsertion surgery. A flowchart to detect electrode migration was designed for clinical practice.Conclusion:
Although electrode migration is a rare complication in CI surgery, long-term follow-up diagnostics should include a test protocol to detect electrode shifts of lateral wall electrode arrays. A reinsertion surgery should be conducted in confirmed patients to recover speech perception.