SUCCESSFUL REVISION OF FAILED COCHLEAR IMPLANTS IN SEVERE LABYRINTHITIS OSSIFICANS

Labyrinthitis ossificans may complicate the insertion of a multichanne l cochlear implant in patients deafened after meningitis. Two children who initially underwent partial insertion of a 22-channel cochlear im plant because of severe cochlear ossification required revision surger y after several months of unsuccessful device use. At the time of revi sion, resection of the ear canal, tympanic membrane, malleus, and incu s provided access to the lateral wall of the cochlea, permitting exten sive drilling of the basal turn and a circumodiolar placement of the e lectrode. Functional integrity of the electronic components of the ori ginal device was documented intraoperatively, avoiding the expense of a new receiver-stimulator. Complete insertion of the active electrodes was accomplished in both cases, and electrophysiologic responsiveness to the implant was documented using intraoperative electrically evoke d auditory brainstem response recordings. Postoperative performance ha s been similar to that of cochlear-implant patients with nonossified e ars. Experience with these two cases suggests that efforts to optimize electrode insertion at the original surgical procedure are appropriat e and may help to avoid the disappointment of an unsuccessful cochlear implant.