Impedance measurements are routinely performed during the cochlear implantation. These measurements make possible to check, whether all electrodes work correctly and are useful in the monitoring of implant's functioning during rehabilitation. The analysis of the impedance's changes makes possible to estimate, what processes happen in tissues and liquids of the inner ear around the electrode.
The aim of the study: The aim of the study was to estimate changes of the electrodes' impedance in cochlear implants users.
Material and methods: Measurements of the impedance was performed on every electrode introduced into the cochlea. Impedance measurements were investigated in 42 adult persons operated at the Department of Otolaryngology Medical University of Lublin. The impedance of electrodes in cochlear implants users was measured during operation, during the activation of the speech processor and during following settings of the speech processor.
Results: During activation of the speech processor we observed elevated values of the impedance, higher then during intra-operating-measurement. On the second fitting impedances decrease and then were stable at this level during one year follow-up.
Conclusions: Increasing values of impedance during first fitting of the speech processor support the hypothesis that a layer of fibrous tissue forms around the electrode because of the inflammatory changes or due to exudation of protein. Such changes could be observed after cochlear implantation. Impedance values decrease after first fitting and remain stable. This may suggest that electrical stimulation prevents from adverse changes in the cochlea.