Intracochlear factors contributing to psychophysical percepts following cochlear implantation: a case study

Abstract

It is conceivable that the variations of performance of cochlear implant patients can be related to several factors. Shiroma et al 1 investigated which factors contributed to the speech recognition ability of cochlear implant patients; multiple regression analysis showed that postoperative psychophysical percepts such as threshold level (T level), maximum comfortable loudness level (C level), and dynamic ranges (DR) may play an important role in speech recognition ability. In this paper, we focus on determining which intracochlear factors contribute to these postoperative psychophysical percepts of the 22-channel cochlear implant system. We made a three-dimensional (3-D) computer reconstruction 2 from the temporal bone of a cochlear implant patient and measured the following factors: distance between the electrode ring's center and the Rosenthal's canal center (dis); the cross-sectional areas of loose and dense fibrous tissue (lft, dft), their sum, fibrous tissue (ft), and new bone (nb) as inner ear pathologic changes; and the density of residual spiral ganglion cells (sgc). The interrelationship between the postoperative psychophysical percepts and these factors is analyzed and discussed.