Migration and other electrode complications following cochlear implantation

To investigate migration and other electrode-related complications in cochlear implant surgery.

Retrospective review of all patients (adult and paediatric) undergoing cochlear implantation at a tertiary referral centre in England, between April 2019 and December 2021. Split arrays and patients who did not have post-op imaging were excluded.

Two hundred and ninety-nine cochlear implants were performed including 90% primary and 10% revision surgeries. Two hundred and forty-eight (86%) of electrodes implanted were straight arrays.Twenty-seven (9%) demonstrated suboptimal position on post-operative imaging. Three (11%) were true migration, 4 (15%) possible migration, 15 (56%) had two or less extra-cochlear electrodes, 3 (11%) expected partial insertion and 2 (7%) demonstrated tip fold-overs. Twenty (74%) of arrays within the suboptimal insertion group were in primary surgeries. Six patients required re-implantation. The most common reason for re-implantation was migration.

Electrode migration after cochlear implantation may be more common than previously thought. We demonstrate rates of migration congruous with current literature; this is despite robust and varied fixation techniques. Notable in our series is that all true captured migrations were seen exclusively in straight arrays. The majority of patients in the possible and confirmed migration group had normal inner ear anatomy.

Suboptimal electrode position following cochlear implant surgery is a recognized complication and can affect implant performance. Reporting may increase with more widespread use of sophisticated post-operative imaging. Use of a pre-curved electrode and routine use of appropriate fixation techniques may reduce migration rates.