Article
Influence of iridium coating and steroid application on the stimulation effect of cochlear implant electrodes
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Published: | August 8, 2007 |
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Introduction: It could be demonstrated that intraoperative intracochlear application of steroids leads to an impedance reduction, which can be ascribed to reduced tissue formation around the electrode carrier. It was the aim of this study to investigate the influence of the treatment on the stimulation effect, i.e. impedance differences in daily measurements using unstimulated and stimulated electrodes.
Methods: All implanted patients received a Contour electrode. The stimulation effect was recorded in the following groups of patients: a) control group (N=17), b) intraoperative steroid application (N=8), c) iridium-coated electrode (N=10), d) iridium-coated electrode coupled with intraoperative steroid application (N=8). The impedances were measured during the first phase of rehabilitation in the morning prior to switching on the speech processor and after at least 4 hours of stimulation using the WinDPS 116 programming software in common ground mode.
Results: Impedance decreases by between 0 and 50% (0 and 5 kΩ) of the initial value measured in the morning prior to switching on the speech processor were found. The highest mean values were measured in patients implanted with the iridium-coated electrode. A correlation between the original impedance values and the stimulation effect was found only in the two steroid-treated groups. The stimulation effect decreased slightly with increasing distance to the initial fitting.
Conclusions: In contrast to the investigation on the impedance development following implantation, neither iridium coating of electrodes nor intraoperative application of steroids showed a significant influence on the stimulation effect.