Evaluation of Residual Hearing in Cochlear Implant Candidates with Asymmetric Hearing Loss Using Multiple Auditory Steady-State Responses

Background: In recent years cochlear implants (CIs) have increasingly become a treatment choice for asymmetric hearing loss. In this group of CI candidates an objective evaluation of residual hearing is essential. Multiple Auditory Steady-state Responses (ASSR) could predict severe-to-profound hearing loss thresholds for subjects being considered for cochlear implantation.

Objective: The aim of our investigation was to find out if multiple ASSR can provide reliable information about residual hearing in CI candidates with asymmetric hearing loss.

Methods: ASSR thresholds in 20 adult CI candidates with asymmetric hearing loss were obtained simultaneously at both ears at 500, 1000, 2000, and 4000Hz, using a multiple-frequency stimulus built up of four narrow-band chirps with a repetition rate of 40Hz. The recording of the multiple steady-state responses was controlled in eight independent recording channels with an adaptive algorithm. A statistical test in the frequency domain was used to detect the response.

Results: The average differences between the behavioural hearing thresholds and the ASSR threshold estimate were 0, 2, 5, and 5 dB for test frequencies of 500, 1000, 2000, and 4000Hz, respectively. No cross-hearing caused by asymmetric hearing loss was found.

Conclusions: Multiple ASSR are an efficient and robust tool for the evaluation of residual hearing in CI candidates with asymmetric hearing loss.