Factors Affecting Performance in Adults With Cochlear Implants: A Role for Cognition and Residual Cochlear Function

Area of Science:

• Audiology
• Neurosurgery
• Biomedical Engineering

Background:

• Cochlear implant (CI) surgery offers significant hearing restoration for adults with severe to profound sensorineural hearing loss.
• Predicting post-operative CI performance remains challenging, with limited understanding of the interplay between cochlear health, cognitive function, and surgical factors.
• Identifying reliable biomarkers for CI outcomes is crucial for patient selection and surgical planning.

Purpose of the Study:

• To evaluate the impact of preoperative and perioperative factors on postlinguistic adult cochlear implant (CI) performance.
• To develop a multivariate prediction model for CI outcomes.
• To validate electrocochleography-total response (ECochG-TR) as a measure of cochlear health relevant to CI stimulation.

Main Methods:

• Prospective cohort study involving 239 postlinguistic adult CI recipients at a tertiary referral center.
• Speech-perception testing (CNC word recognition, AzBio in noise) at 3, 6, and 12 months postoperatively.
• Electrocochleography-total response (ECochG-TR) measured at the round window before electrode insertion.

Main Results:

• ECochG-TR strongly correlated with consonant-nucleus-consonant (CNC) word scores at 6 months (r = 0.71, p < 0.0001).
• A multivariate model including age, hearing loss duration, insertion depth, and ECochG-TR did not significantly improve CNC prediction over ECochG-TR alone.
• AzBio in noise scores showed moderate correlations with Montreal Cognitive Assessment (MoCA; r = 0.38) and ECochG-TR (r = 0.42), with ECochG-TR and MoCA explaining 45.1% of the variability.

Conclusions:

• ECochG-TR is validated as a measure of cochlear health and suitability for CI stimulation.
• The cochlear neural substrate, as indicated by ECochG-TR, is a primary driver of speech perception performance after CI.
• Auditory performance in noise is complex, influenced by both cochlear function (ECochG-TR) and cognitive abilities (MoCA).