Ineraid cochlear implant in the ossified cochlea: surgical techniques and results

Extensive ossification of the cochlea is a common finding in patients with total deafness caused by meningitis, labyrinthitis, or otosclerosis. When the cochlea is totally ossified, the prognosis for achieving free-running speech without lip reading is poor. However, subtotal ossification with residual cochlear patency in the upper basal turn, the middle turn, or the apical turn can be maximally exploited by selective insertion of electrodes. Results can be surprisingly adequate in spite of the poor anatomic conditions. Computed tomography and exploratory cochleotomy, in which electrically evoked auditory brainstem responses are elicited and recorded by intracochlear stimulation are good diagnostic indicators of ossification and residual auditory nerve excitability. "Apical cochleostomy" is an adequate procedure to help penetrate the basal turn in retrograde insertion of the cochlear implant electrode array. Results of this study indicate that the surgical technique and placement of the Ineraid electrode array play a major role in the ability of the patient to achieve understanding of free-running speech.