What factors influence implant success in patients with neurofibromatosis type 2 (NF2) who have undergone both cochlear implantation and auditory brainstem implantation (ABI) for hearing rehabilitation?
If the cochlear nerve is intact, cochlear implantation can be effective for hearing rehabilitation in NF2 patients; however, a significant proportion experience a decline in CI performance. ABI remains the standard option for surgical hearing rehabilitation in NF2, but peak performance is generally lower than that achievable with CIs.
Explore this issue:September 2018
Background: NF2 is an autosomal dominant hereditary disorder characterized by bilateral vestibular schwannomas in 90% to 95% of affected patients. Minimizing morbidity and maximizing the duration of useful hearing can be at odds. Unaidable hearing can be rehabilitated through an ABI, cochlear implant (CI), or both. However, device performance is highly variable and affected by patient and surgical factors.
Study design: Retrospective case series of 10 NF2 patients with both cochlear implantations and auditory brainstem implantations.
Setting: House Clinic, Los Angeles, Calif.
Synopsis: Iowa tests of vowel and consonant recognition, the Northwestern University Children’s Perception of Speech (NU-CHIPS), and City University of New York (CUNY) sentences were performed. Of the 10 patients, there were four right-sided and six left-sided CIs; only one CI was single-channel. Average age at cochlear implantation was 36.8 years. In the recipient ear, average deafness duration was 4.3 years. CI mean scores were NU-CHIPS 61%, Iowa consonants 37%, and Iowa vowels 45%. Mean scores with CIs for CUNY sentences were sound-only mode 42%, lipreading 44%, and sound+lip-reading 78%. Four patients experienced a CI performance reduction to unusable levels over 11 years. Seven patients had right-sided and three patients had left-sided ABIs. Mean age at ABI placement was 39.6 years, and mean deafness duration was 4.3 years. Average follow-up for testing after ABI placement was 6.6 years. ABI mean scores were NU-CHIPS 56%, Iowa consonants 21%, and Iowa vowels 25%. Mean scores with ABIs for CUNY sentences were sound-only mode 5%, lip-reading 45%, and sound+lip-reading 65%. Limitations included a small study population and significant heterogeneity; potentially confounding technology differences; and patient follow-up inconsistency.
Citation: Peng KA, Lorenz MB, Otto SR, Brackmann DE, Wilkinson EP. Cochlear implantation and auditory brainstem implantation in neurofibromatosis type 2. Laryngoscope. March 24, 2018. doi: 10.1002/lary.27181.