INTRACOCHLEAR FACTORS CONTRIBUTING TO PSYCHOPHYSICAL PERCEPTS FOLLOWING COCHLEAR IMPLANTATION

The performance of cochlear implant patients may be related to intraco chlear, histopathological factors. We have performed detailed post-mor tem examinations of five human, implanted cochleas and for each electr ode correlated the psychophysical threshold, comfortable level and dyn amic range with spiral ganglion cell survival, presence of fibrous tis sue and/or new bone, and distance between the centers of the electrode bands and Rosenthal's canal. The psychophysical parameters were stron gly interrelated. Threshold and comfort levels correlated with the dis tance between the electrodes and Rosenthal's canal. Threshold levels a lso correlated with the presence of intracochlear fibrous tissue and n ew bone, especially with the former. The dynamic range showed a negati ve correlation with intracochlear pathology, especially with new bone. Comfort levels and dynamic range were related to spiral ganglion cell survival. The distance between the electrodes and the modiolus increa sed with increasing levels of fibrous tissue and new bone. Spiral gang lion cell survival was decreased with increasing levels of fibrous tis sue and new bone.