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Exemplary comparative studies on explanted cochlear implant (CI) electrodes and the associated clinical data
18 April 2018 (online)
A small percentage of cochlear implant (CI) patients develop a significant deterioration of hearing performance during the wearing period. As a possible cause of this hearing loss, associated with electrode impedance increases, tissue deposits on the platinum electrodes of the implant array are discussed in the literature. To what extent these processes damage the electrode surface was investigated for explanted electrodes using different parameters.
Material and methods:
The individual electrode surfaces of explanted CI-arrays were analyzed by microscopy (light and scanning electron microscopy (SEM)) and classified. Laser microscopic recordings allowed the determination of the surface roughness. The corresponding clinical data were assigned and analyzed.
The visual analysis showed an increase of abrasion of individual electrodes with the residence time (average 11.7 years). The roughness of stimulated electrodes revealed different variations within an array, which were increased compared to non-implanted arrays. The SEM analysis could not detect cell deposits on the electrodes.
The explanted CI electrodes partially show structural changes of the individual electrode surfaces, which can lead to impedance changes.