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Monitoring of residual hearing with electrocochleography for cochlear implantation
18 April 2018 (online)
In the clinical routine, electrocochleography (ECoG) is a well-established method for examining the inner ear as well as the auditory nerve. With the extension of indication criteria for implantation with a cochlear implant (CI) the preservation of residual hearing becomes increasingly important. ECoG measurements can detect the activity of hair cells in the inner ear which are excited by an acoustic stimulus. The CI electrode serves as a receiver for the electric potential which is then transmitted to the computer through the coil.
This prospective ECoG study is planned with 30 participants. Participants will have to have residual hearing and should be scheduled for implantation with an Advanced Bionics CI system. During and after surgery the summation potential is measured using one of the CI electrode contacts. The development of the residual hearing is documented at six appointments in regular intervals after implantation. Summation potentials can be converted into an auditory impression. At the same time, the results are verified using pure tone audiometry.
25 participants have been examined intra- and post-operatively. A good correlation between pure tone thresholds and the converted summation potentials can be observed.
The ECoG measurement is an appropriate method for the objective measurement of auditory thresholds and could possibly replace additional pure tone audiometry measurements in electro-acoustic (EAS) fittings. This method can also be used to provide the surgeon with steady feedback about changing potentials during surgery. Short breaks in the insertion of the electrode array can be applied to let subsided potentials recover and thus preserve residual hearing as best as possible.