Otopathology in a case of multichannel cochlear implantation

The histopathology of the temporal bones of a patient who died of unrelated causes 10 weeks following cochlear implantation using a Richards Ineraid device is presented. Deafness was caused by a prolonged course of intravenous gentamycin therapy 5 years prior to implantation. The electrode array of the cochlear implant was left in situ throughout histologic preparation and sectioning. Despite displacement and disruption of supporting structures of the inner ear, particularly in the 6-to-15-mm range as measured from the round window, there was no significant difference in the mean densities of spiral ganglion cells in the implanted and unimplanted sides. This case is presented as evidence that despite significant disruption of supporting elements of the inner ear, which is common during cochlear implantation, there appears to be little effect on the residual spiral ganglion cell count, at least in the short term.