gms | German Medical Science

The latest Cochlear Implant system allows an expanded range of stimulation rates, assuring that recipients can be programmed with the rate they prefer. Identifying a recipient's optimal rate is time-consuming process and almost impossible in young children. Therefore investigators are looking for objective indicators to predict the preferred rate. Shpak et al (2004) found a correlation between rate preference of CI24 recipients and recovery from refractoriness of the auditory nerve. Recovery functions were obtained using neural response telemetry (NRT).

The hypothesis of this study is that rate preference is correlated with the pathophysiology of the auditory nerve, so that, according to the physiological status of the nerve, the response to the different stimulation rates will be accepted.

First we have obtained the different results and NRT responses in two different groups of candidates: young recipients with short duration of deafness and residual hearing and a second group of patients with long duration of deafness, and no residual hearing. Second we studied the behaviour in different areas of the cochlea in patients with residual hearing preservation after cochlear implantation. In both cases the objective parameters studied were: recipient age, duration of deafness, residual hearing, NRT amplitude growth functions, NRT recovery from refractoriness and NRT rate adaptation.

We also present the preliminary data of the study in 20 CI24RE recipients that were fitted with ACE MAPs at different rates (900 pps/channel and 2400 pps/channel). Auditory nerve pathophysiology is studied by in the light of NRT auditory nerve recovery functions and NRT rate adaptation after pulse trains up to 8 kpps. After 3 months speech tests are performed and the recipients preferred MAP is identified through a questionnaire.