An observation and application of the electrode impedances and electrically-evoked compound action potentials after cochlear implantation using two types of electrodes

Objective:To observe the change of the electrode impedances and the thresholds of the electrically-evoked compound action potentials in different time points after cochlear implantation with M type or R type electrodes for deciding the interval of the mapping.Method:17 cases with Nucleus 24M and 15 cases with Nucleus 24R were inspected the electrode impedance in different time points: intra-operation?initial stimulation in 30 days after operation,and 10,20,30,40,50,60,90,150 days after initial stimulation,and their electrically-evoked compound action potentials were also tested after initial stimulation at the same time.Result:①Compared with the other time points, the electrode impedances at intra-operation and initial stimulation were different with statistical significant(P0.01);②There were different change trends of ECAP thresholds between these two types: M type had a higher ECAP 10 days later after than initial stimulation,R type had reverse records;③The ECAP thresholds of this two types were the lowest 2 months later after initial stimulation, then increased gradually.Conclusion:①The impedance and ECAP thresholds of these two types have obviously changes after initial stimulation;②Mapping can be token regularly after initial stimulation within the 3 months. Then, mapping could be deferred according the performance of the patients.