Objectives/hypothesis: To identify the incidence of and common causes for cochlear implant revision.
Study design: Retrospective case series.
Methods: Operative records were reviewed for all cases of revision cochlear implantation from 1992 to 2006. The causes for reimplantation were classified as hard device failure, soft device failure, exposure/infection, receiver/stimulator migration, and electrode migration. Manufacturers' failure analysis of explanted devices was likewise determined.
Results: Eight hundred and six cochlear implants were performed during the study period including 44 (5.5%) revision procedures. The revision rate was 7.3% for children and 3.8% for adults and reached statistical significant difference. The most common reasons for revision were device failure (78%; 55% hard failure, 23% soft failure) followed by electrode migration (9%) and receiver/stimulator migration (7%). Manufacturers' analysis of failed devices revealed loss of hermetic seal and cracked cases to be the most common causes of failure. Bench analysis of 5/10 explanted devices that were soft failures demonstrated identifiable device defects.
Conclusions: Revision cochlear implant surgery is an infrequent occurrence. Its incidence appears to be higher in children than in adults, although in this series does not appear to be due to increased wound complications, infections, or trauma. Explanted implants that have soft failure as the etiology may have demonstrable defects on bench testing.