[Extended preoperative speech audiometric diagnostics for cochlear implant treatment]

For severe hearing loss and even profound deafness, cochlear implants (CIs) have become the treatment of choice. For establishment of the CI indication, the preoperative Freiburger monosyllabic word recognition (EV) at 65 dB SPL in free field with a hearing aid (EV_HG65) and the maximal understanding (mEV) without a hearing aid with headphones results are important. The goal of this retrospective study was to analyse the correlation of word recognition with a hearing aid at 80 dB SPL (EV_HG80) and mEV. This represents an extension to measuring EV_HG65 compared to mEV and to pure-tone audiometry (4FPTA).

In this study, word recognition with and without a hearing aid was retrospectively analysed for 661 ears. Inclusion criterium was CI implantation at a later date.

During preoperative CI diagnostics, an mEV of 0% was found in 334 ears. The EV_HG65 for 485 ears and the EV_HG80 for 335 ears were also 0%. The EV with hearing aid was found to worsen with increasing 4FPTA at both sound pressure levels, although this effect was smaller at 80 dB SPL than at 65 dB SPL. Including only ears with mEV > 0 % (N = 260 ears), a stronger correlation between EV_HG80 and mEV with a difference of (-4.0 ± 16.4%) in comparison to EV_HG65 and mEV with a difference of (-18.3 ± 16.7%) is seen. This shows a significant difference between mEV and EV_HG80 compared to mEV and EV_HG65.

At a sound pressure level of 65 dB SPL, EV with hearing aid often does not show the accordance with mEV specified by hearing aid and CI guidelines. The EV_HG80 correlates better with mEV than EV_HG65. For clinical diagnosis it is rational to measure speech discrimination with hearing aid at levels higher than 65 dB SPL.