Medical imaging in cochlear implant candidates

A retrospective study of preoperative radiographic surveys obtained in 85 cochlear implant patients was performed. A total of 90 cochlear implant patients were seen at our institution during the last 10 years. In three, the implant was placed at another institution. In two otosclerosis patients, no preimplant radiographic examination was obtained. Meningitis was the cause of deafness in 45 of 90 patients (50 percent); 28 of 40 pediatric age group patients (70 percent), and in 17 of 50 adult patients (34 percent). Thirty-three of 45 postmeningitis patients (73 percent) showed characteristic radiographic signs of sclerosing labyrinthitis or labyrinthitis ossificans. These signs were present in only one other patient who was deaf with unknown cause. Deformity of the inner ear sufficient to explain congenital deafness was noted in three cases; one Mondini deformity and two obliterated base of the cochlea (modiolus). Three otosclerosis patients who had preimplant radiographs, and one congenital syphilis patient showed classic radiographic signs of their respective diseases. Obliteration or stenosis of the round and/or the oval windows were observed in 26 cases drawn from all major etiologic groups. State-of-the-art high resolution, thin-section CT can demonstrate subtle changes that may be the only clue to the cause of deafness. MRI promises to be a useful technique to follow meningitis patients with membraneous labyrinth changes progressing to sclerosing labyrinthitis.