Preserving Residual Hearing in Cochlear Implant Patients

Abstract

Hearing loss is one of the most prevalent disabling conditions in the industrialized world, adversely affecting an individual’s physical, cognitive, behavioral, and social functions. The cochlear implant (CI) is recognized as treatment of choice for profound sensory hearing loss. The CI stimulates the auditory nerve by biphasic electrical pulses that are delivered through electrodes placed inside the cochlea (Fig. 20.1). Due to recent advances in implant technology resulting in better speech recognition CI has been used in people with increasing greater usable residual hearing predominantly in the high frequencies. At the same time, atraumatic electrodes have been designed to preserve the residual hearing in the implanted ear. If hearing could be preserved, then the electrical stimulation of the implant is combined with a hearing aid in the same ear (electrical-acoustical stimulation, EAS). Hearing preservation rates vary between 92 and 70 %. Post implantation hearing loss has multiple possible etiologies and mechanisms, among them are the type and length of electrode, the amount of residual hearing, and the surgical technique. This chapter gives an overview on ongoing efforts to preserve the residual hearing in cochlear implant patients.