Cochlear implant and traumatic lesions secondary to electrode insertion.

On the basis of data reported in the literature, the authors have attempted to define the relationship between the functional results of cochlear implants and possible traumatic damage caused by the insertion of electrodes and their support into the cochlear bony walls. These findings show that traumatic conditions result in functional damage only when they involve the body of Corti's ganglion cells or the central part of their axon, whereas functional results are not influenced by traumatic damage to the peripheral part of the axon. Traumatic damage sustained by other non-nervous structures and the inevitable fibrosis and subsequent bone metaplasia processes which occur when a foreign body penetrates a living organism also appear to be unimportant.