gms | German Medical Science

For a better understanding of the wave propagation in the cochlea in the presence of Cochlear-Implant (CI) electrodes images of implanted human temporal bones with a high resolution of 5.9 μm were built. For a reference an unimplanted temporal bone was scanned at first and the formerly fluid filled spaces (Scala vestibuli and Scala tympani) were segregated from the surrounding bone and the cochlear partition by an image processing software. Then specially prepared CI electrodes without metal (platin) were implanted into four temporal bones to prevent artefacts. Two were inserted by a cochleostomy and two through the round windows. In each case (cochleostomy and round window approach) a standard electrode (l=31 mm) and a short electrode (l'=21 mm) (MED-EL, Innsbruck) were used. Though the electrodes material differs in its absorption property only slightly from the surrounding space it was possible to seperate volume data sets for the electrodes in the form of .stl files. The results show the different influence of insertion techniques and electrode lengths on the damage of the cochlear partition. Obviously there was a smaller degree of cochlear partition damage caused by the insertion of shorter electrodes. Future numerical simulations will show the acoustic influence of CI electrodes on the wave propagation on the basilar membrane. The aim of these further studies is the evaluation of the benefit of additional mechanical stimulation applied to highly hearing impaired patients implanted with CI electrodes.