Cochlear histopathology in the labyrinthectomized ear: implications for cochlear implantation.

Limited damage to the cochlea and preservation of hearing after labyrinthectomy have been the subject of many case reports. One might hypothesize that, even when hearing is lost, there may be less damage to the cochlea than anticipated, and some neural elements that can be electrically stimulated may be preserved. Four labyrinthectomized temporal bones on file at the House Ear Institute were evaluated histopathologically. All had some remaining spiral ganglion cell population, the neural element that we think is stimulated by the intracochlear electrode. We also examined the population of hair cells and dendrites and the presence and extent of cochlear ossification, factors that may influence the performance of a cochlear implant. This is the first study of its type. Results indicate that cochlear implantation in the labyrinthectomized ear may be feasible.