The Effect of Soft Tissue Infections on Device Performance in Adult Cochlear Implant Recipients.

Objective: The aim of this study was to examine the effect of cochlear implant (CI) site infection and its subsequent management on CI mapping and CI performance. Risk factors for CI infections and pathogens causing infections were reviewed. Treatment options for CI infections were examined.
Study Design: Retrospective case review.
Setting: Tertiary referral center.
Patients: Adult patients with a significant CI soft tissue infection from the Northern Cochlear Implant Programme, New Zealand over a 10-year period (August 2004 until August 2014).
Intervention: Patients were treated with intravenous antibiotics, washout and debridement or ex-plantation and reimplantation of CI.
Main Outcome Measure: CI mapping results and implant performance before and after management of CI infections were compared.
Results: There were nine CI infections. Most patients (7/9) were treated with washout and debridement. One patient required removal of the CI and one patient was deemed medically unfit for a general anaesthetic and was managed conservatively with antibiotics alone. Seven patients received long-term antibiotics. Four patients were able to maintain CI performance after salvage treatment of the CI infection. Three patients had poorer CI performance after salvage treatment. One patient had reimplantation and became a nonuser due to only partial reinsertion.
Conclusion: The pathophysiology of CI infections is complex. Infections can occur many years after CI surgery. The most common bacteria identified were Staphylococcus aureus, Pseudomonas aeruginosa, and skin commensals. Biofilms are present around implants that are removed from patients and biofilms may play a role in CI infections, but the mechanism of infection is not clear.