Morphologic study of the guinea pig cochlea after cochlear implantation using the "soft surgery" technique.

Clinical and experimental data appear to indicate that by means of an extremely gentle procedure, known as the "soft surgery" technique, during the insertion of the electrode carrier of the cochlear implant, some level of existing residual hearing can be preserved. By means of an animal model, morphologic changes in the organ of Corti after use of this atraumatic implantation technique were investigated with two types of implants and the results compared. Insertion of the implants was facilitated by lubrication with Healon. In the scanning electron microscopy picture of the organ of Corti, only minor changes in the outer hair cells were observed. As an obligatory reaction of the cochlea to the intracochlear implant, a connective tissue envelope was found around the electrode carrier.