The association of intraoperative electric field and neural excitation patterns of the cochlear implant with patient-related factors of age, gender, cochlear diameter, and postoperative speech measures

Purpose

To assess the relationships between the electric field (EF) and neural excitation patterns in cochlear implants (CIs) and explore their associations with the cochlear diameter, patient age and gender, and postoperative speech recognition.

Method

The intraoperative transimpedance matrix (TIM) and spread of excitation (SOE) measures were computed to obtain their 50 % widths corresponding to six electrode contacts of a lateral-wall electrode array. The measures were then analyzed for intercorrelations, associations with the cochlear diameter, as well as age and gender-related differences. The relationships between the computed intraoperative measures and postimplant speech recognition were also studied.

Results

The TIM and SOE 50 % widths present moderate correlations and exhibit differences between adults and children. The TIM 50 % widths show additional associations with the cochlear diameter and partly vary with the implantee's gender. Speech recognition was found to have a significant relationship with the exponential spread coefficients (ESCs) obtained for individual electrode contacts.

Conclusion

Although interrelated, the EF and neural excitation measures of the CI are associated with different variables. The ESC, derived from computations of the TIM_, is the only measure linked to postoperative speech recognition.