Exploring the capabilities of modern cochlear implants : from electrophysiology to quality of life

Abstract

Cochlear implants (CI) have proved to be a successful treatment for severely and profoundly deaf individuals. There is general agreement that the improvement of speech perception results has been due to ongoing development in CI electrode-array design, new speech processing strategies and by implanting patients with increasing amounts of residual hearing. However, although speech perception scores are very important indicators, there may be other outcomes that give essential information on the benefits of modern CI as outlined in this thesis. By assessing Quality of Life questionnaires and utilities before and after implantation, general health status and cost-utility were evaluated in pre- and postlingually deafened adult populations. In spite of the good results, it was realized that there was still room for improvement. Therefore, a high-rate speech processing strategy was investigated, which gave evidence of further improvement of speech perception performance (especially in noise), provided that the optimum number of electrodes was determined for each patient individually. These data suggested that objective individual parameter selection is obligatory to increase performance. For this purpose, we explored and used objective measures in an experimental and clinical setting to obtain basic knowledge about the electrode-nerve interface and, finally, to optimize individual implant function