Auditory Brainstem Implantation in Chinese Patients With Neurofibromatosis Type II: The Hong Kong Experience

OBJECTIVE:To describe our experience and outcomes of auditory brainstem implantation (ABI) in Chinese patients with Neurofibromatosis Type II (NF2). STUDY DESIGN:Retrospective case review. SETTING:Tertiary referral center. PATIENTS:Patients with NF2 who received ABIs. RESULTS:Between 1997 and 2014, eight patients with NF2 received 9 ABIs after translabyrinthine removal of their vestibular schwannomas. One patient did not have auditory response using the ABI after activation. Environmental sounds could be differentiated by six (75%) patients after 6 months of ABI use (mean score 46% [range 28–60%]), and by five (63%) patients after 1 year (mean score 57% [range 36–76%]) and 2 years of ABI use (mean score 48% [range 24–76%]). Closed-set word identification was possible in four (50%) patients after 6 months (mean score 39% [range 12–72%]), 1 year (mean score 68% [range 48–92%]), and 2 years of ABI use (mean score 62% [range 28–100%]). No patient demonstrated open-set sentence recognition in quiet in the ABI-only condition. However, the use of ABI together with lip-reading conferred an improvement over lip-reading alone in open-set sentence recognition scores in two (25%) patients after 6 months of ABI use (mean improvement 46%), and five (63%) patients after 1 year (mean improvement 25%) and 2 years of ABI use (mean improvement 28%). At 2 years postoperatively, three (38%) patients remained ABI users. CONCLUSION:This is the only published study to date examining ABI outcomes in Cantonese-speaking Chinese NF2 patients and the data seems to show poorer outcomes compared with English-speaking and other nontonal language-speaking NF2 patients. Environmental sound awareness and lip-reading enhancement are the main benefits observed in our patients. More work is needed to improve auditory implant speech-processing strategies for tonal languages and these advancements may yield better speech perception outcomes in the future.