Long-term analysis of ABI auditory performance in patients with neurofibromatosis type 2-related schwannomatosis

This retrospective monocentric study aimed to evaluate long-term auditory brainstem implant (ABI) function in patients with neurofibromatosis type 2, and to investigate the prognostic factors for ABI use.

Between 1997 and 2022, 27 patients with at least five years of follow-up underwent implantation with 32 ABIs. At 1- and 5-years post-implantation and at last follow-up, ABIs were classified as used or non-used and the size of the ipsilateral tumor was recorded. For patients who used their ABIs, we assessed speech perception (disyllabic words, MBAA sentences) in quiet conditions with the ABI only, by lip-reading (LR), and with a combination of the two (ABI + LR). Hearing improvement was calculated as \(\Delta\) $\mathrm{\Delta }$ ABI = (ABI + LR)–LR scores. Predictive factors for ABI use were analyzed.

One year post-implantation, 74% patients were ABI-users and 66% of the ABIs were used. Two of these patients were non-users at five years, and another two at last follow-up (14 ± 5.2 years); 54% of the patients were ABI-users at last follow-up. \(\Delta\) $\mathrm{\Delta }$ ABI revealed a hearing improvement of 32–41% (disyllabic words) and 28–37% (MBAA sentences). Among 16 ABIs with at least LR improvement at 1-year post-implantation, 4 decreased their performance, coinciding with a large growing ipsilateral tumor in 3/4 ABIs. We identified no significant prognostic factors for ABI use.

ABIs are indicated in case of bilateral deafness with a non-functional cochlear nerve. Half the patients with ABIs used their implants and auditory performance remained stable over time, except in cases of ipsilateral tumor growth.