The Impact of Daily Processor Use on Adult Cochlear Implant Outcomes: Reexamining the Roles of Duration of Deafness and Age at Implantation

On the Difficulty of Defining Duration of Deafness for Adults With Cochlear Implants

The amount of time that a person with a cochlear implant experiences severe-to-profound hearing loss before implantation is thought to impact the underlying neural survival, health, and function of the auditory system, thus likely being closely related to post-implantation performance in auditory tasks. The reporting of this number in the research literature is ubiquitous. Although it is most commonly called "duration of deafness," our point of view is that the term is imprecise and the calculation of this number can be nontrivial, particularly for cases of adult onset of hearing loss. We provide suggestions on changing the terminology to "duration of severe-to-profound hearing loss." We also propose a method of determining this number through a series of questions that leads a participant/patient through their progression of hearing loss. We encourage research methodology that requires researchers to explicitly report the process used to determine the duration of severe-to-profound hearing loss with the overall goals of (1) improving rigor and reproducibility in cochlear-implant research and (2) improving the translation between research findings and clinical recommendations.

Cochlear Implantation Outcomes in Older Adults, Ages 80-90

OBJECTIVE

To assess whether postoperative speech recognition after cochlear implantation (CI) differ between age groups of 80 to 89 and 90+.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary academic referral center.

PATIENTS

Older adult (80+ years old) bilateral sensorineural hearing loss patients undergoing CI.

INTERVENTIONS

Therapeutic, CI.

MAIN OUTCOME MEASURES

Speech testing battery at 3, 6, and 12 months postoperatively. Self-reported balance and vertigo symptoms were also assessed.

RESULTS

A total of 221 patients were included in this study, with 171 cases ages 80 to 89 and 50 cases ≥90 years old. A total of 60.3% had an abnormal preoperative cognitive screen based on either Montreal Cognitive Assessment or Mini Mental State Examination. No major demographic or clinical variables were noted across age groups. Mean 1 year postoperative speech scores were as follows for ages 80 to 89 versus 90+, respectively: CNC 50% (±21%) versus 47% (±18%), AzBio Quiet 54% (±26%) versus 50% (±25%), and AzBio +10SNR 28% (±21%) versus 21% (±17%). Age, abnormal cognitive screen, duration of hearing loss, and comorbidity measures such as BMI, Adult Comorbidity Evaluation-27, and American Society of Anesthesiology physical status class were not correlated with any speech measure. Overall rates of persistent self-reported balance symptoms at activation were 22.7%, decreasing to 7.5% at 1 year. Datalogging was >11 hours use on average for both age groups.

CONCLUSIONS

CI speech recognition in the 80 to 89 and 90+ age range significantly improved from preoperative scores. No major speech recognition differences were identified between age groups. Age at implantation, abnormal cognitive screening, and comorbidity status did not influence speech perception, which suggests that candidacy in older adult CI patients should not be withheld strictly due to these parameters.

Cochlear Implant Electrode Placement and Music Perception

Importance

Cochlear implants enable improvements in speech perception, but music perception outcomes remain variable. Image-guided cochlear implant programming has emerged as a potential programming strategy for increasing the quality of spectral information delivered through the cochlear implant to improve outcomes.

Objectives

To perform 2 experiments, the first of which modeled the variance in music perception scores as a function of electrode positioning factors, and the second of which evaluated image-guided cochlear implant programming as a strategy to improve music perception with a cochlear implant.

Design, Setting, and Participants

This single-center, prospective study recruited 50 adult patients with at least 6 months of cochlear implant listening experience and normal cochlear anatomy to participate in experiment 1 from 2013 to 2023. Data analysis was conducted from January to February 2024. Thirty-four of the 50 patients from experiment 1 also completed experiment 2.

Interventions

Cochlear implant programming using a computed tomography-guided electrode selection strategy.

Main Outcomes and Measures

University of Washington Clinical Assessment of Music score, including subtests of pitch discrimination thresholds, isochronous familiar melody recognition, and timbre recognition.

Results

Of 50 participants, 20 (40%) were female, and the mean (SD) age was 57.7 (16.4) years. Experiment 1 suggested that better music perception abilities in the 50 participants were associated with patients who were younger and had a postlingual onset of deafness, as well as electrode arrays with a full scala tympani insertion, higher modiolar distance, and shallower insertion depth. Experiment 2 suggested improvements in melody recognition in the 34 participants using the image-guided cochlear implant programming strategy. Patients with apical electrodes that were deactivated were more likely to demonstrate an improvement in their pitch perception thresholds with the image-guided strategy, likely due to the low-frequency stimuli used in the University of Washington Clinical Assessment of Music.

Conclusions and Relevance

This study identified patient and device factors that were associated with music perception outcomes with a cochlear implant. These findings suggest that a personalized, image-guided approach to programming may improve music perception abilities for patients with cochlear implants.

Speech outcomes in cochlear implant users depend on visual cross-modal cortical activity measured before or after implantation

Cochlear implants can partially restore hearing function in deaf individuals, but long-term speech listening outcomes vary widely across cochlear implant users. Visual cross-modal plasticity, where auditory cortical neurons upregulate visual inputs to assist visual processing, is one factor proposed to worsen cochlear implant users' speech outcomes because it may limit auditory processing capability. However, evidence for this view is conflicting, and the relationship of cross-modal activity to speech perception may depend on other variables such as the type of visual activity and when it is assessed. To clarify, we measured visual cross-modal activity during a silent lip reading task using EEG in a cross-sectional, observational study. The study tested visual brain activation in 14 individuals prior to receiving a cochlear implant, 15 individuals tested at least 1 year after receiving and using a cochlear implant and 13 typical hearing controls who did not use a cochlear implant or hearing aid. Cross-modal responses to the onset of a visual event were positively correlated to speech outcomes in cochlear implant users tested after surgery but were negatively correlated in those tested prior to cochlear implant surgery. In addition, cross-modal increases in neural oscillatory power in the alpha band (8-12 Hz) arising in the lip reading task were associated with worse speech outcomes in both cochlear implant user groups. Taken together, results redress claims that cross-modal plasticity is maladaptive for speech outcomes and instead suggest that this relationship depends on the time point of testing, stage of sensory processing and likely the relevance of the stimulus for speech. In addition, findings form the basis for new neural markers that are predictive of cochlear implant users' long-term speech ability.

Bilateral Simultaneous Cochlear Implants: How Early Activation Influences Wearing Hours

Background/Objectives: Cochlear implantation (CI) is a transformative intervention for individuals with sensorineural hearing loss, providing auditory and speech perception improvements. Traditional CI activation occurs 4-6 weeks post-surgery; however, recent advancements allow for early activation within 1-2 days. The integration of data logging in modern CI systems offers objective insights into processor usage and auditory exposure, which are crucial for optimizing rehabilitation outcomes. Methods: A retrospective study was conducted on 63 patients with bilateral simultaneous CIs using MED-EL SONNET2/RONDO3 devices. Patients were classified into early activation (n = 30, activation within 1-2 days) and classical activation groups (n = 33, activation after day 2). Data logging metrics, patient demographics, and implant details were analyzed using the Wilcoxon rank-sum test and Poisson regression. Results: Daily processor usage did not significantly differ between groups (9.5 ± 3.0 h/day for classical vs. 9.4 ± 3.7 h/day for early activation, p = 0.927). Subgroup analysis showed a significant 18% increase in processor usage with each additional year of patient age (IRR = 1.18, p < 0.001) and a 15% decrease in usage with each year delay in implantation age (IRR = 0.85, p < 0.001) among early activation users. Switch-on frequencies were comparable between groups, with no significant differences observed (p = 1.0). Conclusions: Early activation is feasible and associated with consistent CI usage, providing potential benefits in auditory rehabilitation. Future research should explore its impact on long-term speech and language outcomes to inform evidence-based practices.

Frequency-to-Place Mismatch and Cochlear Implant Outcomes by Electrode Type

Importance

Speech recognition outcomes with a cochlear implant (CI) are highly variable. One factor suggested to correlate with CI-aided speech recognition is frequency-to-place mismatch, or the discrepancy between the natural tonotopic organization of the cochlea and the electric frequency allocation of the CI electrodes within the patient's cochlea.

Objective

To evaluate the association between frequency-to-place mismatch and speech recognition outcomes in a large cohort of postlingually deafened adult CI users, while controlling for various clinical factors known to be associated with those outcomes.

Design, Setting, and Participants

This retrospective cohort study used data from a CI program at a tertiary medical center and included CIs from postlingually deafened adult CI users. After excluding patients whose data were not logged, patients with implantations occurring between 2016 and 2023 were included in the analysis. The data were extracted in November 2023.

Main Outcomes and Measures

Results of the Consonant-Nucleus-Consonant (CNC) monosyllabic word recognition test measured in the CI-aided alone condition 1 month, 3 months, 6 months, and 12 months after activation served as the main outcome. The independent variables included frequency-to-place mismatch, electrode array type, mean modiolar distance, electrode position, age at implantation, biological sex, contralateral hearing abilities, time since CI activation (test interval), and daily device use.

Results

In 498 CIs from 447 postlingually deafened adults (mean [SD] age, 63.1 [17.1] years; 271 [54.4%] CIs with male users), frequency-to-place mismatch was negatively correlated with CI-aided speech recognition outcomes, but the association was only significant for precurved electrode arrays and not straight electrode arrays. In the linear mixed effects model for straight electrode arrays, only test interval (β = 1.14 [95% CI, 0.90-1.38]) and daily device use (β = 0.90 [95% CI, 0.42-1.38]) were correlated with the improvement of word recognition over the first year of device use. In the model for precurved electrode arrays, mismatch at 1500 Hz (β = -0.011 [95% CI, -0.011 to -0.006]), scalar location (β = 16.37 [95% CI, 9.01 to 23.74]), test interval (β = 1.18 [95% CI, 1.18-1.41]) and daily device use (β = 1.65 [95% CI, 1.15-2.14]) all were significantly associated with the improvement of word recognition over the first year of device use.

Conclusions and Relevance

In this cohort study of postlingually deafened adult CI users, including both straight and precurved electrode arrays, daily device use and time since CI activation were found to be significantly associated with improved CI-aided speech recognition outcomes. Frequency-to-place mismatch at 1500 Hz and scalar location were associated with word recognition only for precurved arrays. These findings suggest that, for patients with straight arrays, any interference produced by frequency-to-place mismatch may be overcome by adaptation, which could be supported by daily device use. However, for patients with precurved arrays, daily device use may not be sufficient to completely overcome electrode placement factors, including scalar location and mismatch.

Investigating the effect of cochlear implant usage metrics on cortical auditory-evoked potential responses in adult recipients post-implantation

Introduction

This study examines the effect of cochlear implant (CI) device usage metrics on post-operative outcomes in unilateral CI recipients. The primary objective is to investigate the relationship between CI usage frequency (average daily CI use) and duration (total years of CI use) on electrically evoked cortical auditory-evoked potential (eCAEP) response peak latency (ms) and amplitude (μV).

Methods

Adult CI users (n = 41) who previously exhibited absent acoustically evoked CAEP responses participated in the study. The peak latency and amplitude of eCAEP P1-N1-P2 responses were recorded, when present for the apical, medial, and basal test electrode contacts. CI duration was defined as the number of years between the date of CI activation and date that eCAEP testing was performed. CI usage frequency was defined as the average number of hours per day of audio processor use, which was recorded using the CI programming software.

Results

Overall, 27 participants (65.85%) exhibited detectable eCAEP responses across one or more electrode contacts. Among these, 18 participants (43.9%) elicited eCAEP responses at all three electrode contacts, while 7 (17.07%) showed responses at two contacts, and 2 (4.88%) at one contact. For the remaining 14 participants (34.15%), eCAEP responses were either absent or undetectable. CI usage frequency (average daily CI use [hours/day]) was captured for 32 (78%) of the participants (median 10.35 h/day, range 0.2-16 h/day). Participants with present eCAEP responses for the basal electrode (n = 14) showed significantly higher CI usage frequency (11.8 h/day, p = 0.026) compared to those with non-detectable responses (6.25 h/day). An association was found between higher CI usage frequency and reduced N1 (p = 0.002), P2 (p = 0.0037) and P1-N1 inter-peak (p = 0.015) response latency (ms). While CI duration (total CI use [years]) did not differ significantly between groups based on the presence of eCAEP responses, an association was found between greater CI duration and increased eCAEP response amplitude (μV) for the P2 (p = 0.008) and N1-P2 peak-peak (p = 0.009) response components.

Discussion

Additionally, most (65.85%) participants who previously exhibited absent acoustic CAEP responses developed eCAEP responses after consistent CI use and increased CI experience. These findings may suggest a potential for cortical plasticity and adaptation with consistent CI use over time. Recognizing the impact of device usage metrics on neural responses post-implantation enhances our understanding of the importance of consistent daily CI use. Overall, these findings contribute to addressing the variability among CI users, improving post-operative outcomes and advancing the standard of personalized care in auditory rehabilitation.

Using Machine Learning and Multifaceted Preoperative Measures to Predict Adult Cochlear Implant Outcomes: A Prospective Pilot Study

OBJECTIVES

To use machine learning and a battery of measures for preoperative prediction of speech recognition and quality of life (QOL) outcomes after cochlear implant (CI) surgery.

DESIGN

Demographic, audiologic, cognitive-linguistic, and QOL predictors were collected from 30 postlingually deaf adults before CI surgery. K-means clustering separated patients into groups. Reliable change index scores were computed for speech recognition and QOL from pre-CI to 6 months post-CI, and group differences were determined.

RESULTS

Clustering yielded three groups with differences in reliable change index for sentence recognition. One group demonstrated low baseline sentence recognition and only small improvements post-CI, suggesting a group "at risk" for limited benefits. This group showed lower pre-CI scores on verbal learning and memory and lack of musical training.

CONCLUSIONS

Preoperative assessments can prognosticate CI recipients' postoperative performance and identify individuals at risk for experiencing poor sentence recognition outcomes, which may help guide counseling and rehabilitation.

Cochlear-implant listeners benefit from training with time-compressed speech, even at advanced ages

This study evaluated whether adaptive training with time-compressed speech produces an age-dependent improvement in speech recognition in 14 adult cochlear-implant users. The protocol consisted of a pretest, 5 h of training, and a posttest using time-compressed speech and an adaptive procedure. There were significant improvements in time-compressed speech recognition at the posttest session following training (>5% in the average time-compressed speech recognition threshold) but no effects of age. These results are promising for the use of adaptive training in aural rehabilitation strategies for cochlear-implant users across the adult lifespan and possibly using speech signals, such as time-compressed speech, to train temporal processing.

Improved Postoperative Speech Recognition and Processor Use With Early Cochlear Implant Activation

OBJECTIVE

To report speech recognition outcomes and processor use based on timing of cochlear implant (CI) activation.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

A total of 604 adult CI recipients from October 2011 to March 2022, stratified by timing of CI activation (group 1: ≤10 d, n = 47; group 2: >10 d, n = 557).

MAIN OUTCOME MEASURES

Average daily processor use; Consonant-Nucleus-Consonant (CNC) and Arizona Biomedical (AzBio) in quiet at 1-, 3-, 6-, and 12-month visits; time to peak performance.

RESULTS

The groups did not differ in sex ( p = 0.887), age at CI ( p = 0.109), preoperative CNC ( p = 0.070), or preoperative AzBio in quiet ( p = 0.113). Group 1 had higher median daily processor use than group 2 at the 1-month visit (12.3 versus 10.7 h/d, p = 0.017), with no significant differences at 3, 6, and 12 months. The early activation group had superior median CNC performance at 3 months (56% versus 46%, p = 0.007) and 12 months (60% versus 52%, p = 0.044). Similarly, the early activation group had superior median AzBio in quiet performance at 3 months (72% versus 59%, p = 0.008) and 12 months (75% versus 68%, p = 0.049). Both groups were equivalent in time to peak performance for CNC and AzBio. Earlier CI activation was significantly correlated with higher average daily processor use at all follow-up intervals.

CONCLUSION

CI activation within 10 days of surgery is associated with increased early device usage and superior speech recognition at both early and late follow-up visits. Timing of activation and device usage are modifiable factors that can help optimize postoperative outcomes in the CI population.

Cochlear implant users experience the sound-to-music effect

Introduction

The speech-to-song illusion is a robust effect where repeated speech induces the perception of singing; this effect has been extended to repeated excerpts of environmental sounds (sound-to-music effect). Here we asked whether repetition could elicit musical percepts in cochlear implant (CI) users, who experience challenges with perceiving music due to both physiological and device limitations.

Methods

Thirty adult CI users and thirty age-matched controls with normal hearing (NH) completed two repetition experiments for speech and nonspeech sounds (water droplets). We hypothesized that CI users would experience the sound-to-music effect from temporal/rhythmic cues alone, but to a lesser magnitude compared to NH controls, given the limited access to spectral information CI users receive from their implants.

Results

We found that CI users did experience the sound-to-music effect but to a lesser degree compared to NH participants. Musicality ratings were not associated with musical training or frequency resolution, and among CI users, clinical variables like duration of hearing loss also did not influence ratings.

Discussion

Cochlear implants provide a strong clinical model for disentangling the effects of spectral and temporal information in an acoustic signal; our results suggest that temporal cues are sufficient to perceive the sound-to-music effect when spectral resolution is limited. Additionally, incorporating short repetitions into music specially designed for CI users may provide a promising way for them to experience music.