Long-term Cochlear Implant Users Research Articles

Effect of long-term cochlear implant use on education and occupation: A systematic review

Abstract Purpose: Cochlear implant (CI) technology has improved significantly positively impacting the quality-of-life of the users. Over the past few decades. Nevertheless, the results of the studies on the academic performance of CI users are contradictory in the literature. Aim and objective: The current study aimed to systematically review the articles published in the past 10 years (2011–2021) on the effect of the long-term use of CIs on education and occupational outcomes. Method: The reviewers selected 10 articles from 11,037 in various databases in this systematic review. Results: The review showed mixed results from the selected studies. Some research found that CIs users did worse than their typical peers. In contrast, a few other studies found that CI recipients performed equal to or better than their typical peers or the general population. CI recipients have considerably lower occupational levels than the general population. Many factors could influence educational and occupational outcomes in long-term CI users. Conclusion: Even though there are varied results regarding educational outcomes in long-term CI users, some studies showed good academic performance in CI recipients. However, there is a need for more studies to understand better the factors that affect the educational and occupational abilities of long-term CI users.

The Perception of Regional Dialects and Foreign Accents by Cochlear Implant Users.

Purpose This preliminary research examined (a) the perception of two common sources of indexical variability in speech-regional dialects and foreign accents, and (b) the relation between indexical processing and sentence recognition among prelingually deaf, long-term cochlear implant (CI) users and normal-hearing (NH) peers. Method Forty-three prelingually deaf adolescent and adult CI users and 44 NH peers completed a regional dialect categorization task, which consisted of identifying the region of origin of an unfamiliar talker from six dialect regions of the United States. They also completed an intelligibility rating task, which consisted of rating the intelligibility of short sentences produced by native and nonnative (foreign-accented) speakers of American English on a scale from 1 (not intelligible at all) to 7 (very intelligible). Individual performance was compared to demographic factors and sentence recognition scores. Results Both CI and NH groups demonstrated difficulty with regional dialect categorization, but NH listeners significantly outperformed the CI users. In the intelligibility rating task, both CI and NH listeners rated foreign-accented sentences as less intelligible than native sentences; however, CI users perceived smaller differences in intelligibility between native and foreign-accented sentences. Sensitivity to accent differences was related to sentence recognition accuracy in CI users. Conclusions Prelingually deaf, long-term CI users are sensitive to accent variability in speech, but less so than NH peers. Additionally, individual differences in CI users' sensitivity to indexical variability was related to sentence recognition abilities, suggesting a common source of difficulty in the perception and encoding of fine acoustic-phonetic details in speech.

Long-term auditory processing outcomes in early implanted young adults with cochlear implants: The mismatch negativity vs. P300 response

ObjectiveLong-term outcomes of early implanted, young adult cochlear implant (CI) users remain variable. We measured auditory discrimination by means of event-related potentials in this population to examine whether variability at the level of cortical auditory processing helps to explain speech abilities. MethodsUsing an auditory oddball paradigm, the P300 and Mismatch Negativity (MMN) were measured in 8 young adult CI users and 14 normal-hearing peers. We related P300 amplitude and latency to clinical speech perception scores in quiet and to duration of deafness. ResultsAll individuals showed P300 responses. The MMN response was less robust in both groups. There was no evidence for differences in P300 responses between CI users and controls. P300 amplitude was associated with speech perception scores (r = 0.70, p = .05) and duration of deafness (r = −0.83, p = .009). ConclusionsEarly CI implantation yields good auditory processing outcomes at young adult age and, in contrast to MMN, the P300 provides a robust measure for auditory processing on an individual level. SignificanceAt the cortical level, early implanted, long-term CI users have good auditory discrimination, leaving variability in implantation outcomes unexplained. This group provides unique insight into the long-term neurophysiological underpinnings of early implantation.

Assessing Higher Order Language Processing in Long-Term Cochlear Implant Users.

Purpose The purpose of this study was to describe and explain individual differences in complex/higher order language processing in long-term cochlear implant (CI) users relative to normal-hearing (NH) peers. Method Measures of complex/higher order language processing indexed by the Clinical Evaluation of Language Fundamentals-Fourth Edition (CELF-4) Core Language subtests were obtained from 53 long-term (≥ 7 years) CI users aged 9-29 years and 60 NH controls who did not differ in age, gender, or nonverbal IQ. Vocabulary knowledge and fast, automatic language processing (rapid phonological coding, verbal rehearsal speed, and speech intelligibility) were also assessed. Results CI users showed weaker performance than NH controls on all CELF-4 Core Language subtests. These differences remained for Formulated Sentences and Recalling Sentences even when vocabulary knowledge was statistically controlled. About 50% of the CI sample scored within the range of the NH sample on Formulated Sentences and Recalling Sentences, while the remaining 50% scored well below the NH sample on these subtests. Vocabulary knowledge, rapid phonological coding, verbal rehearsal speed, and speech intelligibility were more strongly correlated with CELF-4 subtest scores in the CI sample than in the NH sample. Conclusions Weaknesses in complex, higher order language processing shown by a subgroup of CI users compared to NH peers may result from delays in fast, automatic processing of language. These at-risk domains of language functioning could serve as targets for novel interventions for deaf children who experience suboptimal spoken language outcomes following cochlear implantation.

Electric-Acoustic Stimulation Outcomes in Children.

This study investigates outcomes in children fit with electric-acoustic stimulation (EAS) and addresses three main questions: (1) Are outcomes with EAS superior to outcomes with conventional electric-only stimulation in children? (2) Do children with residual hearing benefit from EAS and conventional electric-only stimulation when compared with the preoperative hearing aid (HA) condition? (3) Can children with residual hearing derive benefit from EAS after several years of listening with conventional electric-only stimulation? Sixteen pediatric cochlear implant (CI) recipients between 4 and 16 years of age with an unaided low-frequency pure tone average of 75 dB HL in the implanted ear were included in two study arms. Arm 1 included new recipients, and Arm 2 included children with at least 1 year of CI experience. Using a within-subject design, participants were evaluated unilaterally with the Consonant-Nucleus-Consonant (CNC) word list in quiet and the Baby Bio at a +5 dB SNR using an EAS program and a conventional full electric (FE) program. Arm 1 participants' scores were also compared with preoperative scores. Speech perception outcomes were statistically higher with the EAS program than the FE program. For new recipients, scores were significantly higher with EAS than preoperative HA scores for both the CNC and Baby Bio in noise; however, after 6 months of device use, results in the FE condition were not significantly better than preoperative scores. Long-term FE users benefited from EAS over their FE programs based on CNC word scores. Whether newly implanted or long-term CI users, children with residual hearing after CI surgery can benefit from EAS. Cochlear implantation with EAS fitting is a viable option for children with HAs who have residual hearing but have insufficient access to high-frequency sounds and poor speech perception.

Verbal Learning and Memory in Early-Implanted, Prelingually Deaf Adolescent and Adult Cochlear Implant Users.

Purpose The purpose of this study was to investigate the information-processing strategies of early-implanted, prelingually deaf cochlear implant (CI) users with the California Verbal Learning Test-Second Edition (CVLT-II; Delis, Kramer, Kaplan, & Ober, 2000 ), a well-established normed measure of verbal learning and memory used in neuropsychological assessments of memory loss. Method Verbal learning and memory skills were compared in 20 older adolescent and young adult prelingually deaf long-term early-implanted CI users and their 24 normal hearing (NH) peers using the CVLT-II, a widely used multitrial free recall test of verbal learning and memory. Results On average, CI users recalled fewer words than their NH peers across the immediate, delayed, and cued recall trials of the CVLT-II but were comparable to their NH peers on yes/no recognition memory. CI users showed little evidence of semantic clustering of words during free recall but greater serial clustering compared to their NH peers, suggesting fundamental disturbances in automatic semantic activation of words from long-term memory. No differences were found in verbal memory between CI users and their NH peers on measures of retroactive interference and encoding/retrieval interactions. Performance on the 2nd word list of the CVLT-II (List B) and amount of semantic clustering of words during recall were correlated with sentence recognition in the CI group. Conclusion Study findings demonstrate significant differences in free recall performance and information-processing strategies that early-implanted, prelingually deaf CI users use to encode, organize, store, and retrieve spoken words in conventional verbal list learning paradigms, compared to their NH peers. Because verbal learning and memory are core foundational processes routinely used in daily functioning for a wide range of neurocognitive and language processing operations, these findings suggest potential domains for assessment and novel interventions to promote the development of optimal outcomes in prelingually deaf early-implanted long-term CI users.

High-Variability Sentence Recognition in Long-Term Cochlear Implant Users: Associations With Rapid Phonological Coding and Executive Functioning.

The objective of the present study was to determine whether long-term cochlear implant (CI) users would show greater variability in rapid phonological coding skills and greater reliance on slow-effortful compensatory executive functioning (EF) skills than normal-hearing (NH) peers on perceptually challenging high-variability sentence recognition tasks. We tested the following three hypotheses: First, CI users would show lower scores on sentence recognition tests involving high speaker and dialect variability than NH controls, even after adjusting for poorer sentence recognition performance by CI users on a conventional low-variability sentence recognition test. Second, variability in fast-automatic rapid phonological coding skills would be more strongly associated with performance on high-variability sentence recognition tasks for CI users than NH peers. Third, compensatory EF strategies would be more strongly associated with performance on high-variability sentence recognition tasks for CI users than NH peers. Two groups of children, adolescents, and young adults aged 9 to 29 years participated in this cross-sectional study: 49 long-term CI users (≥7 years) and 56 NH controls. All participants were tested on measures of rapid phonological coding (Children's Test of Nonword Repetition), conventional sentence recognition (Harvard Sentence Recognition Test), and two novel high-variability sentence recognition tests that varied the indexical attributes of speech (Perceptually Robust English Sentence Test Open-set test and Perceptually Robust English Sentence Test Open-set test-Foreign Accented English test). Measures of EF included verbal working memory (WM), spatial WM, controlled cognitive fluency, and inhibition concentration. CI users scored lower than NH peers on both tests of high-variability sentence recognition even after conventional sentence recognition skills were statistically controlled. Correlations between rapid phonological coding and high-variability sentence recognition scores were stronger for the CI sample than for the NH sample even after basic sentence perception skills were statistically controlled. Scatterplots revealed different ranges and slopes for the relationship between rapid phonological coding skills and high-variability sentence recognition performance in CI users and NH peers. Although no statistically significant correlations between EF strategies and sentence recognition were found in the CI or NH sample after use of a conservative Bonferroni-type correction, medium to high effect sizes for correlations between verbal WM and sentence recognition in the CI sample suggest that further investigation of this relationship is needed. These findings provide converging support for neurocognitive models that propose two channels for speech-language processing: a fast-automatic channel that predominates whenever possible and a compensatory slow-effortful processing channel that is activated during perceptually-challenging speech processing tasks that are not fully managed by the fast-automatic channel (ease of language understanding, framework for understanding effortful listening, and auditory neurocognitive model). CI users showed significantly poorer performance on measures of high-variability sentence recognition than NH peers, even after simple sentence recognition was controlled. Nonword repetition scores showed almost no overlap between CI and NH samples, and correlations between nonword repetition scores and high-variability sentence recognition were consistent with greater reliance on engagement of fast-automatic phonological coding for high-variability sentence recognition in the CI sample than in the NH sample. Further investigation of the verbal WM-sentence recognition relationship in CI users is recommended. Assessment of fast-automatic phonological processing and slow-effortful EF skills may provide a better understanding of speech perception outcomes in CI users in the clinical setting.

Electrical dynamic range is only weakly associated with auditory performance and speech recognition in long-term users of cochlear implants

ObjectiveThe electrical dynamic range (EDR) has been suggested to be related to auditory performance in cochlear implant (CI) users. However, few reports have evaluated postlingual CI users who have used CIs for long periods in comparison with prelingual CI users. Here, we evaluated auditory perception and speech performance in terms of the EDR in long-term CI users. The EDR, and auditory and speech performances, were compared between pre- and post-lingual CI users. MethodsWe enrolled all patients who received CIs from April 2000 to December 2010 at Seoul National University Hospital, and who had ≥5 years of experience with CIs. The EDRs affording subjective responses at the threshold level (T-level) and comfortable level (C-level) were analyzed in terms of their relationships with pure tone audiometry levels, speech evaluation scores, including those on the Phonetically Balanced (PB) Word List test, vowel and consonant tests, a sentence test, and the Korean version of the Central Institute for the Deaf (K-CID) test; we also calculated Category in Auditory Performance (CAP) scores. ResultsWe found no significant difference in the average EDR, CAP, K-CID, PB word, consonant, or vowel scores between pre- and post-lingual CI users. The EDR was weakly associated with the PB word (P = 0.003, r = 0.462) and consonant scores (P = 0.005, r = 0.438). Other speech evaluations, such as the CAP, K-CID, and vowel scores, were not significantly associated with the EDR T-level. We found no association between pure tone thresholds at 0.5, 1, or 2 kHz, and the speech evaluation scores or EDRs of low-, middle-, or high-frequency channels. ConclusionsThe EDR was only weakly associated with speech performance, such as scores on consonant and PB word tests in long-term CI users, irrespective of pre- or post-lingual deafness status.

Short-Term and Working Memory Impairments in Early-Implanted, Long-Term Cochlear Implant Users Are Independent of Audibility and Speech Production.

To determine whether early-implanted, long-term cochlear implant (CI) users display delays in verbal short-term and working memory capacity when processes related to audibility and speech production are eliminated. Twenty-three long-term CI users and 23 normal-hearing controls each completed forward and backward digit span tasks under testing conditions that differed in presentation modality (auditory or visual) and response output (spoken recall or manual pointing). Normal-hearing controls reproduced more lists of digits than the CI users, even when the test items were presented visually and the responses were made manually via touchscreen response. Short-term and working memory delays observed in CI users are not due to greater demands from peripheral sensory processes such as audibility or from overt speech-motor planning and response output organization. Instead, CI users are less efficient at encoding and maintaining phonological representations in verbal short-term memory using phonological and linguistic strategies during memory tasks.

Verbal processing speed and executive functioning in long-term cochlear implant users.

The purpose of this study was to report how verbal rehearsal speed (VRS), a form of covert speech used to maintain verbal information in working memory, and another verbal processing speed measure, perceptual encoding speed, are related to 3 domains of executive function (EF) at risk in cochlear implant (CI) users: verbal working memory, fluency-speed, and inhibition-concentration. EF, speech perception, and language outcome measures were obtained from 55 prelingually deaf, long-term CI users and matched controls with normal hearing (NH controls). Correlational analyses were used to assess relations between VRS (articulation rate), perceptual encoding speed (digit and color naming), and the outcomes in each sample. CI users displayed slower verbal processing speeds than NH controls. Verbal rehearsal speed was related to 2 EF domains in the NH sample but was unrelated to EF outcomes in CI users. Perceptual encoding speed was related to all EF domains in both groups. Verbal rehearsal speed may be less influential for EF quality in CI users than for NH controls, whereas rapid automatized labeling skills and EF are closely related in both groups. CI users may develop processing strategies in EF tasks that differ from the covert speech strategies routinely employed by NH individuals.

Concept Formation Skills in Long-Term Cochlear Implant Users

This study investigated if a period of auditory sensory deprivation followed by degraded auditory input and related language delays affects visual concept formation skills in long-term prelingually deaf cochlear implant (CI) users. We also examined if concept formation skills are mediated or moderated by other neurocognitive domains (i.e., language, working memory, and executive control). Relative to normally hearing (NH) peers, CI users displayed significantly poorer performance in several specific areas of concept formation, especially when multiple comparisons and relational concepts were components of the task. Differences in concept formation between CI users and NH peers were fully explained by differences in language and inhibition-concentration skills. Language skills were also found to be more strongly related to concept formation in CI users than in NH peers. The present findings suggest that complex relational concepts may be adversely affected by a period of early prelingual deafness followed by access to underspecified and degraded sound patterns and spoken language transmitted by a CI. Investigating a unique clinical population such as early-implanted prelingually deaf children with CIs can provide new insights into foundational brain-behavior relations and developmental processes.

Pitch Adaptation Patterns in Bimodal Cochlear Implant Users: Over Time and Long‐term

Objectives: (1) Characterize pitch adaptation patterns in bimodal long-electrode cochlear implant (CI) users over time, and correlate these with electrode discrimination and speech perception outcomes. (2) Compare to pitch plasticity observed in hybrid CI users. Methods: Observational cohort over a 12-month period after CI activation or of long-term CI experience. Severe to profound hearing impairment in 19 newly activated bimodal CI users and 20 long-term CI users was studied in an audiology clinic. Outcome measures: Electric-to-acoustic pitch matches, audiometric thresholds, electrode discrimination performance, and speech perception scores, measured over time. Results: Recently activated (12 months) subjects had these pitch adaptation patterns: pitch-adapting, pitch-dropping, and pitch-unchanging. Long-term subjects had a parallel set of adaptation patterns: matched-pitch, low-pitch, and nonmatched-pitch. Unlike hybrid CI users who are mostly pitch-adapting/matched-pitch, the majority of bimodal CI users demonstrated pitch-dropping/low-pitch or pitch-unchanging/nonmatched-pitch. Subjects with pitch-adapting/matched-pitch patterns trended towards better low-frequency thresholds. Changes in electrode discrimination were not associated with pitch differences between electrodes. Reductions in speech perception scores over time were associated with dropping-pitch patterns. Conclusions: Bimodal CI users with more residual hearing seem similar to hybrid CI users in adapting pitch perception to reduce mismatch with the frequencies allocated to the electrodes and acoustic hearing. In contrast, those with less residual hearing exhibit no adaptation or a drop in the pitches of the basal electrodes. Our data suggest that electrode discrimination does not depend on perceived pitch differences between electrodes. Speech perception may depend more on pitch perception and the ability to distinguish pitch between electrodes.

Psychosocial adjustment in adolescents who have used cochlear implants since preschool.

This study examined psychosocial characteristics of students who had used a cochlear implant (CI) since preschool and were evaluated when they were in elementary grades and again in high school. The study had four goals: (1) to determine the extent to which psychosocial skills documented in elementary grades were maintained into high school; (2) to assess the extent to which long-term CI users identified with the Deaf community or the hearing world or both; (3) to examine the association between group identification and the student's sense of self-esteem, preferred communication mode, and spoken language skills; and (4) to describe the extracurricular world of the teenagers who were mainstreamed with hearing age-mates for most of their academic experience. As part of a larger study, 112 CI students (aged 15.0 to 18.6 yrs) or their parents completed questionnaires describing their social skills, and a subsample of 107 CI students completed group identification and self-esteem questionnaires. Results were compared with either a control group of hearing teenagers (N = 46) or age-appropriate hearing norms provided by the assessment developer. Average psychosocial ratings from both parents and students at both elementary grades and high school indicated a positive self-image throughout the school years. Seventy percent of the adolescents expressed either strong identification with the hearing community (32%) or mixed identification with both deaf and hearing communities (38%). Almost all CI students (95%) were mainstreamed for more than half of the day, and the majority of students (85%) were in the appropriate grade for their age. Virtually all CI students (98%) reported having hearing friends, and a majority reported having deaf friends. More than 75% of CI students reported that they used primarily spoken language to communicate and that good spoken language skills enabled them to participate more fully in all aspects of their lives. Identification with the hearing world was not associated with personal or social adjustment problems but was associated with better speech perception and English language skill. Ninety-four percent were active participants in high school activities and sports, and 50% held part-time jobs (a rate similar to that documented for hearing teens). The majority of these early-implanted adolescents reported strong social skills, high self-esteem, and at least mixed identification with the hearing world. However, these results must be viewed in light of possible sources of sample selection bias and may not represent the psychosocial characteristics of the entire population of children receiving CIs.

Effects of communication mode on skills of long-term cochlear implant users.

Effects of communication mode on skills of long-term cochlear implant users.

Neural plasticity detected in short- and long-term cochlear implant users using PET.

The interaction of listening to words and watching sign language in short-term and long-term cochlear implant (CI) users who have learned sign language after becoming deaf was measured using PET. In short-term CI users the auditory cortex was inactive while in long-term CI users it was fully activated with the simultaneous presentation of auditory and visual input. The result suggests the possibility that the interference of rival modalities may be diminished with experience and the preference switchover from the visual input to the auditory input could be accomplished by means of the neural plasticity persisting in the mature human auditory cortex.