Cochlear structures after implantation of a perimodiolar electrode array.

OBJECTIVE: A perimodiolar prototype electrode array has been evaluated on 12 human temporal bone specimens. To achieve modiolar proximity, a fine Teflon positioner is attached to the tip and base of a conventional Nucleus 22 electrode array.
METHODS: Intracochlear electrode position was examined by macroscopic preparation and confirmed by a cochlear view x-ray after insertion into human temporal bones. The temporal bones were examined with light microscopy for intracochlear trauma after insertion, explantation, and re-implantation of the perimodiolar array.
RESULTS: Macroscopic preparation and x-ray confirmed close proximity of the intracochlear electrodes to the modiolar wall. In some bones, electrode insertion and positioning was performed without significant damage to intracochlear structures, but explantation caused varying degrees of trauma depending on the explantation technique used. Re-implantation and repeat explantation appeared to destroy most of the intracochlear architecture.
CONCLUSIONS: The perimodiolar electrode array prototype with Teflon positioner cannot be recommended for clinical use, especially in children in whom the possibility for re-implantation is high.