Importance of perimodiolar electrode position for psychoacoustic discrimination in cochlear implantation

Abstract

Hypothesis: Modiolar proximity of the cochlear implant electrodes and low impedance values have a positive effect on electrical pitch discrimination. Background: The proximity of the cochlear electrode to the modiolar wall can determine changes in tissue and fluid environment. With the onset of soft-surgery techniques, the trauma caused during surgery has been reduced, minimizing fibrous growth. Methods: Computed tomography-scan measurements of electrode-inner wall distance and psychoacoustic electrode discrimination tests were done. Neural Response Telemery and impedance data were used in the study. Results: It was found that patients fitted with perimodiolar arrays have lower impedance values and smaller electrodeinner wall distances than those fitted with straight arrays. These variables were significantly correlated to electrode discrimination. It was found that a closer distance to the modiolus also results in better electrode discrimination. Conclusion: Perimodiolar electrodes could be a better solution in terms of pitch discrimination both because they are closer to the modiolus and because their impedance is lower.