The influence of residual high-frequency hearing on the outcome in congenitally deaf cochlear implant recipients

Objective: To show that congenitally deaf children who receive a cochlear i mplant between 10 and 15 years of age find it significantly more difficult to learn the new signal, and that a history of sound detection at high freq uencies with hearing aids is predictive of better outcomes in these childre n. Study Design: A retrospective study using a within-subjects design. Setting: Children's Cochlear Implant Centre, Sydney (CCIC), Royal Prince Al fred Hospital, and the New Children's Hospital in Westmead are tertiary ref erral centers. Patients: Forty-five congenitally deaf patients were grouped according to t heir age tin years) at implantation into group I (aged 10-15), group 2 (age d <10), group 2a (aged 6-9), and group 2b (aged 3-5). Within each group, in dividuals with previous hearing between 2 acid 4 kHz before receiving a coc hlear implant were identified, and their mean results were compared with th ose in their respective age-matched groups. Interventions: Surgical implantation, intensive weekly habilitation at the CCIC. Main Outcome Measures: Speech perception, speech production, and language m easures were compared. Questionnaires and telephone interviews were conduct ed. Results: Group 2 (age <10 years) consistently outperformed group 1 (10-15 y ears) on all outcome measures, and most of them learned to converse without lipreading. In group 1, children with previous aided hearing at high frequ encies displayed exceptional gains in speech perception and speech producti on, with reduced dependence on lipreading. Previous high frequency hearing does not benefit group 2. Conclusions: Implant recipients aged 10 to 15 years experience more difficu lty than younger children during the initial periods of device use. A histo ry of high-frequency hearing before implantation in these individuals corre lates with more rapid improvement.