Using cortical auditory-evoked potential responses to verify the objective benefit of aural rehabilitation in adult cochlear implant users.

Introduction: Cortical auditory-evoked potential (CAEP) responses are used clinically to assess auditory processing and support cochlear implant (CI) mapping procedures post-implantation. This study aims to examine CAEP responses as an objective measure of neurophysiological changes following a structured Aural Rehabilitation Program (ARP) in long-term adult CI users, with poor baseline speech perception performance. Advancing our understanding of the mechanisms underlying improved post-implantation outcomes in poor performing CI users may inform the development of targeted interventions and refinement of evidence-based rehabilitation strategies. Methods: Adult unilateral CI users with post-lingual deafness were recruited for an intensive clinician-directed ARP incorporating structured active listening exercises. The ARP consisted of weekly 1-h face-to-face sessions over 10 weeks with repeated assessments at baseline (T0) and 10-week intervals (T10, T20, T30). Participants were allocated to immediate (Group 1), 10-week delay (Group 2), or 20-week delay (Group 3) ARP groups, while a control group completed assessments without intensive ARP. Speech perception in quiet [CNC phoneme and word scores (%)] and electrically-evoked CAEP (eCAEP) response [P1-N1-P2 peak latencies (ms) and amplitudes (μV)] measures were collected at each time point for all groups. The repeated measures design incorporated staggered pre- and post-ARP periods for Groups 1-3 (T0-T10, T10-T20, and T20-T30, respectively). CNC and eCAEP measures were analyzed pre- and post-ARP intervention and across assessment intervals (T0-T30) to evaluate rehabilitation effects and account for natural variability and potential ongoing adaptation in auditory performance over time, independent of ARP-related changes. Results: No significant changes were observed in eCAEP response latencies or amplitudes from pre- to post-rehabilitation. However, the ARP intervention group demonstrated significantly higher CNC phoneme and word recognition scores compared to the control group in both implant-alone and binaural listening conditions post-rehabilitation. Discussion: No measurable neurophysiological changes were observed in eCAEP responses from pre- to post-rehabilitation. However, the ARP intervention group demonstrated behavioral improvements, reflected in marginal increases in speech perception scores at both phoneme and word recognition levels, which were not observed in the control group. These findings highlight the clinical value of structured aural rehabilitation in supporting improved outcomes for long-term adult CI users with poor baseline performance.