| Acoustic hearing in combination with electric stimulation provided by a cochlear implant in postlingually hearing impaired subjects: Auditory performance The thesis aims to gain insight in auditory performances in acoustic hearing in combination with electric stimulation provided by a cochlear implant (CI). In this respect, two main conditions exist which provide this bimodal listening situation.;The first part of the thesis describes the ipsilateral combination of both modalities, called electric acoustic stimulation (EAS). While the benefits of hearing preservation (HP) in EAS users are widely known and agreed upon, there existed no widely used system to quantify HP. Therefore, the thesis describes the development of the HP classification system, which was found to be suitable for all CI users with measurable pre-operative residual hearing (RH). If adopted as a universal standard, as it was designed to be, it should prove highly beneficial for meta-analysis. Subsequently, the system was used to report on the long-term (LT) HP data. A small continuous decline of 3% HP per year was observed. Nevertheless, LT speech perception results showed a continuous statistically significant improvement over time. Nowadays, the benefits of structure preservation (SP) surgery are also recognized for all CI users, even those whose RH is not functional. Hence, the thesis describes the achieved HP and the improved auditory performances after CI with the flexible 28-mm electrode in patients with severe to profound hearing losses as well as in candidates with functional low-frequency hearing.;The bimodal condition of electric stimulation in a unilateral hearing loss (UHL) ear and thus contralateral acoustic hearing is described in part two of the thesis. The restoration of binaural effects in these UHL CI recipients could be demonstrated with speech in noise testing, sound localization and subjective evaluation, up to three and ten years post-implantation. However, the ability to use binaural input takes several years of CI use. Furthermore, high levels (100%) of LT CI use were found, which represent the indispensability and the cost-effectiveness of the implant in this population. In addition to the LT binaural benefits, the thesis demonstrates LT stable tinnitus reduction, which supports that a CI in UHL subjects is a durable treatment for incapacitating tinnitus in the deaf ear.;As a result of expanding CI inclusion criteria and new technologies, there is a growing number of CI candidates with ipsi -and/or contralateral RH. The mode of transmission is different between acoustic and electrical stimulation. However, the thesis has proven that the LT marriage between both is beneficial, in the ipsilateral as well as in the bilateral combination. |
