Examination of Electrical Evoked Parameters in Cochlear Implantees

Background: Cochlear implants can restore hearing in hard of hearing patients by electrical stimulation of the auditory nerve. To optimize the electrical stimulation, thus improving hearing sensitivity and speech reception, fine programming of the cochlear implant’s sound processor is crucial. The quality and quantity of sound information transmitted is substantially influenced by the electrically evoked comfort levels, being fine-tuned on the basis of many other electrophysiological parameters (i.e. ART, ESRT).

Objective and methods: Patients were recruited into postlingual and praelingual groups based on their speech development stage, then data were statistically analysed. Following the registration of parameters (i.e. electrode array impedance, intraoperative ESRT, ART, evoked comfort-, threshold levels, etc.) results were underwent inter-group and inter-subject analysis.

Results: During the rehabilitation process three phases could be defined depending on varying micro environmental alterations. Fluctuations in the objective electrophysiological parameters were correlated to these phases and tendencies.

I.Phase: adaptation. It is represented by increased electric evoked comfort levels.
II.Phase: stabilization. The previously gained individual maximum electric evoked values start to become invariable.
III.Phase: regeneration. Electric evoked comfort levels show decreasing tendencies.

In the majority of implantees within a single study group the fluctuation of these phases show similar tendencies, but may alter between the two study groups.

Conclusion: The rehabilitation process after cochlear implantation always takes substantially long time with the necessity to estimate the outcome performance. The psychophysical parameters of the prae- and postlingual groups were statistically comparable, thus results of the adult population may help us in fitting of non-cooperating patients’ sound processors.