Cochlear implantation in patients with neurofibromatosis type 2: Variables affecting auditory performance

Objective: To investigate cochlear implant performance outcomes among patients with Neurofibromatosis type 2 (NF2). Study Design: Retrospective case series, patient questionnaire, and systematic review of the literature. Setting: Tertiary academic referral center. Patients: All patients with NF2 having an anatomically intact ipsilateral cochlear nerve who underwent cochlear implantation (CI). Intervention(s): Cochlear implantation. Main Outcome Measures: Postimplantation audiometric performance and patient perceived benefit. Results: Ten patients met study criteria. The median duration of follow-up after CI was 42 months (mean, 46.9 mo; range, 12-97 mo). Five patients received previous microsurgical resection of their ipsilateral vestibular schwannoma, 4 underwent previous stereotactic radiosurgery, and 1 patient had no tumor treatment before CI. Nine subjects achieved sound awareness, 6 attained open-set speech recognition and 7 are daily users. Variables including prolonged auditory deprivation, cochlear ossification, unfavorable electrical promontory stimulation testing, and useful contralateral hearing were associated with poor cochlear implant performance. No statistical associations were found between open-set recognition capacity and previous tumor management strategy, surgical approach, or ipsilateral tumor size. Conclusion: Cochlear implantation is an attractive alternative to auditory brainstem implantation for hearing rehabilitation in patients with NF2. Approximately 70% of patients achieve open-set speech discrimination, many scoring at the ceiling of audiometric testing. Given a favorable risk profile and superior audiometric outcomes, CI should be strongly considered in patients with nonserviceable hearing who have an anatomically intact cochlear nerve, whereas auditory brainstem implantation should be reserved for patients with evidence of cochlear nerve loss. Akin to conventional cochlear implant recipients, prolonged hearing loss, unfavorable electrophysiological testing, and cochlear ossification may predict poor subject performance. Finally, useful hearing in the contralateral ear may present a barrier to daily device use.