Management of Electrode Exposure After Cochlear Implantation

Migration and other electrode complications following cochlear implantation

OBJECTIVES

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

METHODS

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.

RESULTS

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.

DISCUSSION

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.

CONCLUSION

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.

Systematic Review of Postcochlear Implant Electrode Migration: What Is Known?

BACKGROUND AND OBJECTIVES

Electrode migration after cochlear implantation (CI) is a rare complication that accounts for 1to 15% of all revision surgery. This study is a systematic review of the literature for investigating the knowledge and approaches to the incidence of electrode migration after CI.

METHODS

A systematic electronic search of the literature was carried out using PubMed, Cochrane, Virtual Health Library, Scopus and Web of Science (ISI). All original articles that reported electrode migration after CI surgery were included. The Newcastle-Ottawa Scale and CARE checklist were utilized for the assessment of the risk of bias. Descriptive data analysis was performed using SPSS software.

RESULTS

A total of 26 studies including 4,316 patients were included. Out of them, 289 patients had electrode migration following CI. To diagnose electrode migration, traditional computed tomography scan was used in 13 studies, while cone-beam computed tomography was applied in three studies. In addition, electrode migration was detected during intraoperative exploration in eight studies. The most common presenting symptom was change in sound/poor performance (n = 43) followed by pain sensation (n = 15) and facial nerve stimulation (n = 10). Cholesteatoma was the most common associated pathology (n = 10) followed by infection (n = 9) and ossification of the basal turn of the cochlea (n = 8).

CONCLUSION

Electrode migration is a major complication of CI and could be more common than previously thought. As it may occur with or without clinical complaints, long-term follow-up through routine radiological scanning is recommended. Further studies are warranted to identify the underlying mechanism of electrode extrusion and the appropriate fixation method.

Cochlear implant electrode array exposure: A delayed complication

Exposure of the cochlear implant electrode array as a late complication has been reported rarely in the literature. A retrospective analysis revealed 4 patients presenting with exposure of their cochlear implant electrode arrays from 2 to 17 years after implantation. Data collected from these 4 patients were surgical implantation approach, type of implant, age at implant, interval between implant and complication, surgical correction of the problem, pathology at the time of correction, and length of follow-up after intervention. All 4 patients presented with otitis or mastoiditis. Each had undergone a transmastoid approach with facial recess and cochleostomy and full implant insertion. In 3 cases, the tympanic membrane had retracted to expose the electrode array. In 1 patient, the electrode array had eroded through the external canal, lateral to the facial recess. The exposed arrays were addressed surgically, including explantation/reimplantation for 1 patient. Cochlear implant electrode arrays can become exposed by relative migration of the array and the tympanic membrane. Implant surgeons and audiologists need to be aware of the possibility of this complication. Closure of the ear canal appears to be the most effective surgical intervention.