Pediatric cochlear implant fitting parameters in inner ear malformation: Is it same with normal cochlea?

The aim was to evaluate the cochlear implant (CI) mapping parameters of CI users with inner ear malformation (IEM) and to reveal the changes in parameters over time.

In total, 118 CI users were included with 127 ears (68-IEM; 59-normal cochlear anatomy) in present retrospective study. The impedance measurements, thresholds levels-THR, most comfortable levels- MCL, pulse width-PW and rate values were analyzed in both IEM and control group at the initial activation, 6th,12th and 24th months postoperatively.

There were statistically significant differences in impedance measurements in several time points. And also, there was a remarkable difference in THR & MCL and PW values between IEM and control groups in all time points (p < 0.05). THR & MCL levels and PW values increased significantly between all time periods in both groups (p < 0,008) and values of parameters in IEM-group were higher than those of control group. When comparing rates, statistically significant difference was observed only at the initial activation in both within (p < 0.001) and between groups (p = 0.03).

Pediatric CI users with IEM need individual changes in fitting parameters. More frequent map sessions should be planned as they require more PW, THR and MCL increase over time. The increase rate differs between IEM subgroups depending on the deviation of malformation from the normal cochlear anatomy. This study is the first to in its attempt to reveal the mapping characteristics and long-term changes in pediatric CI users with different IEM subgroups.