Clinical selection criteria for a second cochlear implant for bimodal listeners

Area of Science:

• Audiology
• Neuroscience
• Speech-Language Pathology

Background:

• Bilateral hearing restoration, using either two cochlear implants (CIs) or a CI with a contralateral hearing aid (HA), aims to improve speech perception.
• The comparative benefit of these approaches, particularly in relation to residual hearing in the non-implanted ear for bimodal users, requires further investigation.

Purpose of the Study:

• To compare the speech perception benefits between individuals with bilateral CIs and those with a CI and a contralateral HA (bimodal users).
• To evaluate the impact of residual hearing on speech perception outcomes in bimodal users.

Main Methods:

• A repeated measures design was employed with 25 adult participants (12 bilateral CI users, 13 bimodal users).
• Bimodal users were categorized into 'poor' (aided pure-tone average [PTA] ≥ 55 dB HL at 1 kHz or lower) and 'good' (aided PTA < 55 dB HL) groups.
• Speech recognition (consonant, vowel, sentence) was assessed in quiet and noise under different device configurations (CI alone, HA alone, CI+HA; first CI alone, second CI alone, bilateral CIs).

Main Results:

• No significant difference in vowel and sentence recognition benefit was observed between the 'good' bimodal group and the bilateral CI group.
• Bilateral CI users demonstrated significantly greater binaural benefit across all speech measures compared to the 'poor' bimodal group.

Conclusions:

• The aided pure-tone average at 1 kHz or lower may be a clinical indicator for recommending a second CI in bimodal users.
• Bilateral CI implantation may offer superior binaural listening benefits for individuals with poorer unaided hearing in the non-implanted ear.