Cochlear reimplantation: causes of failure, outcomes, and audiologic performance

To review Quebec's experience with cochlear reimplantation in adults and children and describe failure rates, causes of revision, surgical findings, and the impact of reimplantation on audiologic performances.

Retrospective analysis of all 45 cochlear implant revision surgeries (43 reimplantations) performed on 16 adults and 25 children at the Centre Hospitalier Universitaire de Québec (Hôtel-Dieu de Québec) in Quebec City, between 1987 and 2005.

: Data on patient demographics, failure sources including review of manufacturer's investigation reports, surgical findings, and outcomes (electrode insertion, complications, and audiologic performances).

Mean length of device use before explantation was 5.5 years and ranged from 3 months to 17 years. Explantation was related to documented hard failure (53.3%), traumatic device failure (13.3%, only in children), extrusion of electrode array or scalp flap infection (13.3%), a decrease in performance or soft failure (11.1%), intratemporal pathology (6.7%), and a perilymphatic fistula (2.2%). Overall revision rates of 8.0% and 5.4% were obtained for children and adults, respectively. Total device failure rates of 6.2% in children and 3.3% in adults were calculated. Failure rates decreased with each new generation of Nucleus devices. Perioperative complications were uncommon. A moderate amount of fibrosis was found in the cochlea lumen, and sometimes osteoneogenesis made the reinsertion challenging. Electrode reinsertion depth was mostly comparable with the initial surgery. Speech perception abilities were maintained after reimplantation.

Management of implant failures, including revision surgeries, is becoming an increasingly important part of cochlear implant program activity. It appears more commonly in children because of trauma. Medical and audiologic outcomes are generally excellent. Revision implantation appears to be a safe and effective procedure.