Article
Restoration of hearing and speech perception by auditory brainstem implants in Neurofibromatosis type 2
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Published: | May 13, 2014 |
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Objective: To improve auditory quality obtained by auditory brainstem implants (ABI) after loss of auditory nerves in Neurofibromatosis Type 2 (NF2).
Method: In a consecutive series of 27 patients with NF2, ABI implantation was performed under multimodality monitoring including mapping of the dorsal cochlear nucleus for electrical auditory brainstem responses (E-ABR). Clinical outcome was evaluated by standardized syllable and word tests and HSM (Hochmair-Schulz-Moser) sentence test at auditory-only and audio-visual conditions.
Results: Out of 27 implanted patients, there were 24 successful hearing restorations. Causes of failures were radiotherapy, anatomical variation or fast disease progress. In 17 patients open set speech perception could be documented at a range of 10% to 99% correct understanding of unknown text in auditory-only mode, mean 44%. Patients’ ages, tumor extensions and tumor volumes were no negative predictors. Positive predictors for open speech perception were a minimal number of 6 active electrodes and a maximal duration of deafness below 2 years (P<0.1).
Conclusions: This study documents that open set speech recognition in pure auditory mode is now a realistic goal by ABI. Pre-conditions to optimize results are exact ABI placing under electropyhsiological mapping, and adequate timing within the first two years of deafness.