Auditory Brainstem Implant in Neurofibromatosis Type 2 and Non-Neurofibromatosis Type 2 Patients

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Abstract
To evaluate the auditory brainstem implant (ABI) performances in neurofibromatosis type 2 (NF2) and non-NF2 patients. Retrospective cohort study. Tertiary referral center. Between 1996 and 2006, 31 adult patients (mean age, 41 yr; range, 17-65 yr) were implanted with a 21-electrode Nucleus device (Cochlear Inc., Lane Cove, Australia). The population comprised 23 NF2, 3 postmeningitis bilateral ossified cochleas, 3 solitary vestibular schwannomas on the only hearing ear, 1 inner ear malformation, and 1 bilateral cochlear destruction by otosclerosis. Auditory brainstem implant was placed through a translabyrinthine or a retrosigmoid approach. Auditory brainstem implant was evaluated by open-set words and sentences in sound, vision, and sound-plus-vision modes. In NF2 patients, 16 (70%) were daily users of their implants. In these patients, the open-set dissyllabic word recognition was 36 +/- 6.0 % for vision-only mode, 33 +/- 6.5 % for sound-only mode, and 65 +/- 8.0 % in vision-plus-sound mode with a high interindividual variation. Negative prognostic factors were long duration of total hearing loss (>10 yr), low number of active electrodes (<10), and local complications (meningitis, hematoma). Six non-NF2 patients (75%) were daily ABI users. The performances of patients with ossified cochleas were similar to best NF2 cases. A clear benefit of ABI could be evidenced in NF2 patients, especially in case of small tumor and short duration of hearing loss. Auditory brainstem implant may also be indicated in patients with bilateral profound hearing loss and a predictable failure of cochlear implantation.