Study On The Correlation Between Electrode Impedance And Electrode Position

Objective:Analysis of the impedance characteristics of cochlear implant electrodes,The relationship between the electrode impedance and the electrode position was discussed by measuring the electrode impedance at different positions to guide the start-up and debugging after operation.Methods:The temporal bone CT examination and cochlear implantation were performed in our hospital from 2013 to 2018,and the implant was SONATA device of MED-EL cochlear implant company in Austria,A total of 349 patients(373 ears)underwent temporal bone CT and electrode impedance test in our hospital after surgery.The inner ear was divided into the normal group and the incomplete group according to the comprehensive conditions such as whether the inner ear was deformed or not,whether the posterior cochlear lesion was present or not,and whether the electrode was completely implanted in the cochlea.The relationship between the electrode impedance and the electrode position is discussed by measuring the electrode impedance at different positions.Results:1.In the normal group,the overall electrode impedance was the lowest during the operation and the highest at startup,and the differences were statistically significant(P<0.05),and gradually decreased after startup.There was no statistically significant difference between the impedance values 6 months after the operation and 1 year after the operation(P>0.05).The electrode impedance at the same position in different periods was the lowest during the operation and the highest at startup,with statistically significant difference(P<0.05),and then the decrease tended to be stable.The impedance values of electrodes at different positions in the same period were the highest at the apex of the cochlea,and the difference was statistically significant(P<0.05).2.In the incomplete implantation group,the overall electrode impedance value was the lowest during surgery and the highest at startup,with statistically significant differences(P<0.05),and decreased after startup.The impedance of the electrodes in the bottom part of the cochlea was the lowest during the operation(P<0.05),and the difference was statistically significant(P<0.05).The impedance of the electrodes increased at startup,and the difference was not statistically significant between startup and 1 year after the operation(P>0.05).During the same period,the impedance values of the internal electrodes of the cochlea at different locations were the highest during the operation and 3 months after the operation,and the difference was statistically significant(P<0.05).3.There was no significant difference in electrode impedance between the normal group and the implantation group(P>0.05).4.In the implantation group with incomplete electrode,there was no statistically significant difference between the impedance value of the outer segment of the cochlea and that of the bottom segment of the cochlea during the same period of operation and startup(P>0.05).At the same time from 2 months to 1 year after surgery,there was a statistically significant difference between the electrode impedance at the bottom of the cochlea and that at the outer part of the cochlea(P<0.05).Conclusion : For cochlear implant users with SONATA implant and cochlear implant brand,they are products of Austrian company Med-el.1.Under normal circumstances,the overall change trend of electrode impedance is the lowest during the operation,the highest at startup,then decreases,and tends to be stable at 6 months after the operation.The impedance change of each segment is similar to that of the whole electrode.The electrode impedance of the apex of the cochlea was the highest within 1 year after the operation.2.When implantation is incomplete: the overall change trend of impedance of the inner electrode of the cochlea is the lowest during the operation,the highest at startup,and then decreases.The basal segment of the cochlea was increased at the lowest starting point during the operation and became stable after starting.The electrode impedance of the apex of the cochlea was the highest within 3 months after the operation.3.It is not possible to accurately determine the position of the inner electrode according to the impedance value of the electrode.4.The impedance of the adjacent electrodes at the end of the electrode varies greatly and the presence of open circuit indicates the presence of external electrode of the cochlea.