Long-term Deafness Research Articles

Long-term experience with biohybrid cochlear implants in human neurosensory restoration

Objective The implantation of biohybrid electrodes was introduced a few years ago in our clinic. These electrodes coated with autologous mononuclear cells releasing anti-inflammatory and neuroprotective factors are thought to reduce insertion trauma and maintain the vitality of surviving spiral ganglion neurons. The clinical feasibility of this approach has already been demonstrated. In the present retrospective study, the four-year results of the two sides (classical electrode and biohybrid electrode) in the bilaterally implanted patients were compared in order to investigate possible adverse long-term effects. Methods All patients received a complete audiological diagnosis which also included a speech audiogram and impedance measurement. The measurements were carried out 1 month, 3 months, 6 months, 1 year, 2 years, 3 years and 4 years after implantation. The hearing results were assessed by pure tone audiometry. Results All patients showed satisfactory speech understanding and similar impedances on both sides although they had a long-term deafness before implantation of the side provided with a biohybrid electrode array. The results of speech understanding and impedance measurements were stable for years. Cone beam computed tomography was performed in 4 patients three years after implantation and could rule out cochlear ossification. Other complications were also not registered in any of the patients. Conclusion Due to satisfactory outcomes and lack of complications, the biohybrid electrode is considered to be a safe option in cochlear implantation. The simplicity of application of autologous cells as a source of anti-inflammatory and neuroprotective factors via a biohybrid electrode array is a key step for cell-based, regenerative therapies for deafness.

Importance of age at 2nd implantation and interimplant interval to the outcome of bilateral prelingually deafened pediatric cochlear implantation.

In Taiwan, the number of cases of sequential bilateral pediatric cochlear implantation (CI) is increasing but data regarding its effectiveness and impact of the reimbursement policy are lacking. We examined the speech perception and quality of life (QOL) of bilateral prelingually deaf children who underwent sequential CI, considering the effects of age at the time of second implantation and interimplant interval. We enrolled 124 Mandarin-speaking participants who underwent initial cochlear implant (CI1) in 2001-2019 and a second CI (CI2) in 2015-2020. Patients were followed up for ≥2 years and were categorized into groups based on age at the time of CI2 implantation (<3.5, 3.6-7, 7.1-10, 10.1-13, and 13.1-18 years) and interimplant interval (0.5-3, 3.1-5, 5.1-7, 7.1-10, and >10 years). We evaluated speech perception, device usage rates, and QOL using subjective questionnaires (Speech, Spatial, and Qualities of Hearing and Comprehension Cochlear Implant Questionnaire). Speech perception scores of CI2 were negatively correlated with ages at the time of CI1 and CI2 implantation and interimplant interval. Older age and a longer interimplant interval were associated with higher nonuse rates for CI2 and worse auditory performance and QOL. Among individuals aged >13 years with interimplant intervals >10 years, up to 44% did not use their second ear. Patients aged 7.1 to 10 years had better speech perception and higher questionnaire scores than those aged 10.1 to 13 and 13.1 to 18 years. Furthermore, patients aged 10.1 to 13 years had a lower rate of continuous CI2 usage compared to those aged 7.1 to 10 years. Timely implantation of CI2 is essential to achieve optimal outcomes, particularly among sequentially implanted patients with long-term deafness in the second ear and no improvement with hearing aids following CI1 implantation. For CI2 implantation, an upper limit of age of 10 years and interimplant interval of 7 years are essential to prevent suboptimal outcomes. These data can provide useful information to implant recipients, their families, and medical and audiological professionals, enabling a comprehensive understanding of the benefits and potential impacts of the timing of CI2 implantation.

Study on damage of the macrostructure of the cochlea under the impact load.

Due to the tiny and delicate structure of the cochlea, the auditory system is the most sensitive to explosion impact damage. After being damaged by the explosion impact wave, it usually causes long-term deafness, tinnitus, and other symptoms. To better understand the influence of impact load on the cochlea and basilar membrane (BM), a three-dimensional (3D) fluid-solid coupling finite element model was developed. This model accurately reflects the actual spatial spiral shape of the human cochlea, as well as the lymph environment and biological materials. Based on verifying the reliability of the model, the curve of impact load-amplitude response was obtained, and damage of impact load on the cochlea and the key macrostructure-BM was analyzed. The results indicate that impact wave at middle frequency has widest influence on the cochlea. Furthermore, impact loading causes tears in the BM and destroys the cochlear frequency selectivity.

Functional Outcomes and Quality of Life after Cochlear Implantation in Patients with Long-Term Deafness.

Background: Hearing-related quality of life (QoL) after cochlear implantation (CI) is as important as audiological performance. We evaluated the functional results and QoL after CI in a heterogeneous patient cohort with emphasis on patients with long-term deafness (>10 years). Methods: Twenty-eight patients (n = 32 implanted ears, within n = 12 long-term deaf ears) implanted with a mid-scala electrode array were included in this retrospective mono-centric cohort study. Speech intelligibility for monosyllables (SIM), speech reception thresholds (SRT50) and QoL with Nijmegen Cochlear Implant Questionnaire (NCIQ) were registered. Correlation of SIM and QoL was analyzed. Results: SIM and SRT50 improved significantly 12 months postoperatively up to 54.8 ± 29.1% and 49.3 ± 9.6 dB SPL, respectively. SIM progressively improved up to 1 year, but some early-deafened, late implanted patients developed speech understanding several years after implantation. The global and all subdomain QoL scores increased significantly up to 12 months postoperatively and we found a correlation of SIM and global QoL score at 12 months postoperatively. Several patients of the “poor performer” (SIM < 40%) group reported high improvement of hearing-related QoL. Conclusions: Cochlear implantation provides a benefit in hearing-related QoL, even in some patients with low postoperative speech intelligibility results. Consequently, hearing-related QoL scores should be routinely used as outcome measure beside standard speech understanding tests, as well. Further studies with a prospective multi-centric design are needed to identify factors influencing post-implantation functional results and QoL in the patient group of long-term deafness.

Electrically evoked auditory brainstem responses to electrical stimulation at round window membrane in congenitally deaf children at different ages

ObjectivesTo investigate the usefulness of measuring the electrically evoked auditory brainstem responses (eABRs) to electrical stimulation at the round window niche (RWN) and round window membrane (RWM) and the effect of deafness duration on functions of the auditory pathway to the level of the brainstem. MethodsAccording to the age at cochlear implantation (CI), 99 children with profound sensorineural hearing loss were divided into four groups: ≤12 months (group A), 13–36 months (group B), 37–60 months (group C) and >60 months (group D). The eABRs were evoked by electrical stimulation at RWN and RWM during the operation of CI. ResultsThe higher eABR extraction rate and lower threshold for RWM stimulation was found than those for RWN stimulation. The eⅢ latencies and eⅢ-eⅤ latency intervals for RWM stimulation were similar among four groups. However, children with earlier CI (group A) showed a significantly shorter eⅤ latency than others. ConclusionThe eABR evoked by the electrical stimulation at RWM is more stable and sensitive compared with that at RWN for evaluating functions of the auditory conduction pathway. Development in the upper brainstem pathway may be more vulnerable to long-term deafness as revealed by the eⅤ latency.

Expression and Localization of Kv1.1 and Kv3.1b Potassium Channels in the Cochlear Nucleus and Inferior Colliculus after Long-Term Auditory Deafferentation.

Deafness affects the expression and distribution of voltage-dependent potassium channels (Kvs) of central auditory neurons in the short-term, i.e., hours to days, but the consequences in the expression of Kvs after long-term deafness remain unknown. We tested expression and distribution of Kv1.1 and Kv3.1b, key for auditory processing, in the rat cochlear nucleus (CN), and in the inferior colliculus (IC), at 1, 15 and 90 days after mechanical lesion of the cochlea, using a combination of qRT-PCR and Western blot in the whole CN, along with semi-quantitative immunocytochemistry in the AVCN, where the role of both Kvs in the control of excitability for accurate auditory timing signal processing is well established. Neither Kv1.1/Kv3.1b mRNA or protein expression changed significantly in the CN between 1 and 15 days after deafness. At 90 days post-lesion, however, mRNA and protein expression for both Kvs increased, suggesting that regulation of Kv1.1 and Kv3.1b expression is part of cellular mechanisms for long-term adaptation to auditory deprivation in the CN. Consistent with these findings, immunocytochemistry showed increased labeling intensity for both Kvs in the AVCN at day 90 after cochlear lesion. This increase argues that up-regulation of Kv1.1 and Kv3.1b in AVCN neurons may be required to adapt intrinsic excitability to altered input over the long term after auditory deprivation. Contrary to these findings in the CN, expression levels of Kv1.1 and Kv3.1b in the IC did not undergo major changes after cochlear lesion. In particular, there was no evidence of long-term up-regulation of either Kv1.1 or Kv3.1b, supporting that such post-lesion adaptive mechanism may not be needed in the IC. These results reveal that post-lesion adaptations do not necessarily involve stereotyped plastic mechanisms along the entire auditory pathway.

Duration of unilateral auditory deprivation is associated with reduced speech perception after cochlear implantation: A single-sided deafness study

Objective: Examine the relationship between duration of unilateral deafness and speech perception outcomes after cochlear implantation in adults with single-sided deafness.Methods: A systematic review of PubMed articles containing individual speech perception and duration of deafness data from single-sided deaf adults. Studies were selected for detailed review and duration of deafness and speech perception outcomes were extracted, with speech scores reported as percent correct. A linear regression as a function of study and length of deafness was performed.Results: A statistically significant negative effect of duration of unilateral deafness on speech perception was found, but there was substantial uncertainty regarding the strength of the effect.Discussion: Existing data make it difficult to either support or reject a hard 5- or 10-year unilateral auditory deprivation limit on cochlear implant (CI) candidacy for patients with single-sided deafness. This is because the totality of available data are consistent with a very small effect, perhaps negligible in practical terms, and just as consistent with a very large effect. Regardless of effect size, the present results have important basic implications. They suggest that unilateral sound deprivation may have a deleterious effect on auditory processing even though more central parts of the auditory system have continued to receive input from a contralateral normal ear.Conclusions: Speech perception scores in SSD patients are negatively correlated with duration of deafness, but the limited amount of data from cochlear implant users with long-term single-sided deafness leads to substantial uncertainly, which in turn precludes any strong clinical recommendations. Further study of SSD CI users with long-term deafness will be necessary to generate evidence-based guidelines for implantation criteria in this population.

Predicting Performance and Non-Use in Prelingually Deaf and Late-Implanted Cochlear Implant Users.

To analyze postoperative hearing performance and independent predictors of speech perception and to assess cochlear implant nonuse in adults with prelingual deafness who received an implant during adulthood. Retrospective cohort study including all prelingually deaf adults who received a cochlear implant at the University Medical Center Utrecht between 2000 and 2013. Tertiary referral center. Included were a total of 48 prelingually deaf patients diagnosed with severe to profound sensorineural hearing loss before the age of 2 years who received their implants during adulthood. Postoperative monosyllabic word and sentence recognition scores. The average maximum postoperative monosyllabic word score for all subjects was 25% correct. Preoperative speech perception and the extent of preoperative residual hearing were both positive independent predictors of postoperative speech recognition, explaining 47% of the variance. Almost half of the population experienced only little (27%) or no benefit (21%) of their implants in daily communication. These patients were more likely to have either no or only low-frequency residual hearing. Eventually, all subjects without any benefit became non-user. Postoperative performance of adult, prelingually deaf cochlear implant candidates, with long-term deafness is dependent on their preoperative speech perception and residual hearing. Candidates who have negligible residual hearing are expected to have no or only limited postoperative benefit of their implants and are at risk of becoming nonusers.

Cochlear implants in the social courts

Since the indication for receiving acochlear implant (CI) has widened (single-sided deafness [SSD], electric acoustic stimulation [EAS], bilateral CI, CI for long-term deafness), more and more patients come into consideration for such atreatment. Hence, disputes increasingly arise between patients and their insurance companies concerning the question of whether surgery and follow-up treatment have to be paid for by statutory health insurance. This work provides an overview of judgments rendered by the German social courts. We investigated whether and in which cases it is advisable for apatient to go to court, and how long the proceedings may take. We looked for judgments in the two biggest commercial legal databases and in the database of the German social courts, using combinations of the search parameters "Cochlear," "Cochlea," "Implant," and "Implantat." Three verdicts were attained by directly contacting the court; another one was mentioned in an article. The reviewed judgements were issued between 2003 and 2017. A total of 12judgments were found. The patients won in all but one of the main proceedings. The case that was lost concerned exceptional circumstances. One patient didn't get the desired interim measure, but won in the main proceedings. The proceedings took between 1year and 8months, and 9years and 5months. Despite the amount of time the patient has to invest, taking legal action is worthwhile. The proceedings at the social courts are generally exempt from charges. In most cases, the statutory health insurance is ordered to pay for aCI.

Hearing Restoration for Adults with Vestibular Schwannoma in the Only Hearing Ear: Ipsilateral or Contralateral Cochlear Implantation?

Objective: To explore auditory outcomes following cochlear implantation (CI) in patients with vestibular schwannoma (VS) in the only hearing ear. Methods: Three patients, all with a long history of hearing loss on one side and with newly diagnosed VS on the other side, underwent ipsilateral or contralateral CI. Their clinical data were collected retrospectively. Postoperative hearing outcomes were measured during follow-up and compared with the preoperative test results. A thorough search of the English-language literature was performed. Results: Patients 1 and 2 underwent CI in the ipsilateral and contralateral ear, respectively, without tumor removal; patient 3 underwent CI after tumor resection. At the last follow-up, the result of pure-tone audiometry was 25, 45, and 25 dB, respectively. An open-set speech discrimination score was achieved in all 3 patients, with monosyllabic word recognition of 60, 30, and 75%, respectively. Besides the patients included in our study, 28 CI cases with VS in the only hearing ear have been reported up to now. Conclusions: In patients with VS in the only hearing ear, significant hearing deterioration with no obvious tumor growth is a good indication for ipsilateral CI. Long-term deafness in the tumor-free ear is not an absolute contraindication for CI.

Exploring consequences of short- and long-term deafness on speech production: A lip-tube perturbation study

Studies have reported strong links between speech production and perception. We aimed to evaluate the role of long- and short-term auditory feedback alteration on speech production. Eleven adults with normal hearing (controls) and 17 cochlear implant (CI) users (7 pre-lingually deaf and 10 post-lingually deaf adults) were recruited. Short-term auditory feedback deprivation was induced by turning off the CI or by providing masking noise. Acoustic and articulatory measures were obtained during the production of /u/, with and without a tube inserted between the lips (perturbation), and with and without auditory feedback. F1 values were significantly different between the implant OFF and ON conditions for the pre-lingually deaf participants. In the absence of auditory feedback, the pre-lingually deaf participants moved the tongue more forward. Thus, a lack of normal auditory experience of speech may affect the internal representation of a vowel.

Multisensory training improves auditory spatial processing following bilateral cochlear implantation.

Cochlear implants (CIs) partially restore hearing to the deaf by directly stimulating the inner ear. In individuals fitted with CIs, lack of auditory experience due to loss of hearing before language acquisition can adversely impact outcomes. For example, adults with early-onset hearing loss generally do not integrate inputs from both ears effectively when fitted with bilateral CIs (BiCIs). Here, we used an animal model to investigate the effects of long-term deafness on auditory localization with BiCIs and approaches for promoting the use of binaural spatial cues. Ferrets were deafened either at the age of hearing onset or as adults. All animals were implanted in adulthood, either unilaterally or bilaterally, and were subsequently assessed for their ability to localize sound in the horizontal plane. The unilaterally implanted animals were unable to perform this task, regardless of the duration of deafness. Among animals with BiCIs, early-onset hearing loss was associated with poor auditory localization performance, compared with late-onset hearing loss. However, performance in the early-deafened group with BiCIs improved significantly after multisensory training with interleaved auditory and visual stimuli. We demonstrate a possible neural substrate for this by showing a training-induced improvement in the responsiveness of auditory cortical neurons and in their sensitivity to interaural level differences, the principal localization cue available to BiCI users. Importantly, our behavioral and physiological evidence demonstrates a facilitative role for vision in restoring auditory spatial processing following potential cross-modal reorganization. These findings support investigation of a similar training paradigm in human CI users.

Is there a deafness duration limit for cochlear implants in post-lingual deaf adults?

Conclusion: Patients with post-lingual deafness should not be excluded from cochlear implantation (CI) on the basis of duration of deafness. We found that the prognosis was favorable in patients who developed deafness after adolescence, even in those with extremely long-term deafness. Objectives: CI is an effective treatment for post-lingual deafness. However, it remains unclear whether CI would benefit patients with extremely long-term deafness. We evaluated the auditory performance after CI of patients who had been deaf for more than 30 years. Methods: The study enrolled 81 adults with post-lingual deafness. Speech perception tests were performed preoperatively and 12 months postoperatively, and factors affecting the postoperative auditory performance were investigated. The subjects were divided into groups according to the duration of deafness and the postoperative speech perception scores were compared. Results: A marked improvement in the open-set speech perception scores (mono/disyllabic words and sentences) after implantation was seen in all groups, and no significant difference in the improvement in speech perception scores was observed among the groups. Age at onset of deafness was closely related to the postoperative performance, and patients who had lost their hearing before adolescence performed poorly.

Cochlear implants in adults over 60: A study of communicative benefits and the impact on quality of life

ObjectivesQuantifying the improvement in quality of life (QoL) of cochlear implant (CI) patients over 60, its relation to audiometric benefits and the subjective impact on specific areas of life.MethodsAn observational retrospective study was conducted on 26 individuals (17 male and 9 female) older than 60, all implanted in our unit between 1 January 1999 and 31 January 2009. And 10 patients (5 male and 5 female) aged between 40 and 60 were the control group. A full postoperative audiological evaluation was completed. Sociodemographic characteristics and history of hearing loss were collected. To evaluate QoL benefits, the Glasgow Benefit Inventory test and the Specific Questionnaire were filled in.ResultsPatients in the test and control groups had similar preoperative speech recognition levels. Preoperative audiometric thresholds were significantly worse in patients from 40 to 60 years of age although they scored better in speech recognition after implantation. Patients experienced significant improvement in their QoL in all areas, especially in general health, while they experienced a smaller improvement in social interaction. Age, duration of deafness, and years wearing the processor were statistically related to QoL regardless of audiometric benefit. Unilateral CI users and patients without tinnitus obtain better QoL although no statistical relation was found.ConclusionsCochlear implantation improves QoL of patients over 60 by the mere fact of having been implanted, regardless of poorer audiological benefits. Older patients, with long-term deafness experience a greater improvement in QoL after implantation. The results of this study should aid other centers when counseling patients on the expected, daily functional benefits of cochlear implantation.

Behavioral training restores temporal processing in auditory cortex of long-deaf cats

Temporal auditory processing is poor in prelingually hearing-impaired patients fitted with cochlear prostheses as adults. In an animal model of prelingual long-term deafness, we investigated the effects of behavioral training on temporal processing in the adult primary auditory cortex (AI). Neuronal responses to pulse trains of increasing frequencies were recorded in three groups of neonatally deafened cats that received a cochlear prosthesis after >3 yr of deafness: 1) acutely implanted animals that received no electric stimulation before study, 2) animals that received chronic-passive stimulation for several weeks to months before study, and 3) animals that received chronic-passive stimulation and additional behavioral training (signal detection). A fourth group of normal adult cats that was deafened acutely and implanted served as controls. The neuronal temporal response parameters of interest included the stimulus rate that evoked the maximum number of phase-locked spikes [best repetition rate (BRR)], the stimulus rate that produced 50% of the spike count at BRR (cutoff rate), the peak-response latency, and the first spike latency and timing-jitter. All long-deaf animals demonstrated a severe reduction in spiral ganglion cell density (mean, <6% of normal). Long-term deafness resulted in a significantly reduced temporal following capacity and spike-timing precision of cortical neurons in all parameters tested. Neurons in deaf animals that received only chronic-passive stimulation showed a gain in BRR but otherwise were similar to deaf cats that received no stimulation. In contrast, training with behaviorally relevant stimulation significantly enhanced all temporal processing parameters to normal levels with the exception of minimum latencies. These results demonstrate the high efficacy of learning-based remodeling of fundamental timing properties in cortical processing even in the adult, long-deaf auditory system, suggesting rehabilitative strategies for patients with long-term hearing loss.

Pitfalls in the management of monaural deafness

We report a patient who underwent cochlear implantation in an ear with long-term deafness, after an acoustic neuroma had been removed surgically from the other, hitherto good ear and the cochlear nerve had subsequently been resected to relieve severe tinnitus. Case report. The patient could not tolerate the cochlear implant, because of a moderate headache due to the stimulation level necessary for environmental sound discrimination. Cochlear implantation in patients with long-term deafness should be considered carefully, even if deafness is monaural.

Mismatch negativity and adaptation measures of the late auditory evoked potential in cochlear implant users

A better understanding of the neural correlates of large variability in cochlear implant (CI) patients’ speech performance may allow us to find solutions to further improve CI benefits. The present study examined the mismatch negativity (MMN) and the adaptation of the late auditory evoked potential (LAEP) in 10 CI users. The speech syllable /da/ and 1-kHz tone burst were used to examine the LAEP adaptation. The amount of LAEP adaptation was calculated according to the averaged N1-P2 amplitude for the LAEPs evoked by the last 3 stimuli and the amplitude evoked by the first stimulus. For the MMN recordings, the standard stimulus (1-kHz tone) and the deviant stimulus (2-kHz tone) were presented in an oddball condition. Additionally, the deviants alone were presented in a control condition. The MMN was derived by subtracting the response to the deviants in the control condition from the oddball condition. Results showed that good CI performers displayed a more prominent LAEP adaptation than moderate-to-poor performers. Speech performance was significantly correlated to the amount of LAEP adaptation for the 1-kHz tone bursts. Good performers displayed large MMNs and moderate-to-poor performers had small or absent MMNs. The abnormal electrophysiological findings in moderate-to-poor performers suggest that long-term deafness may cause damage not only at the auditory cortical level, but also at the cognitive level.

Long-Term Evaluation of Prelingually Deaf Subjects Implanted During Adolescence and Adulthood

Cochlear Implantation (CI) can be considered the elective choice for the treatment of severe and profound hearing loss. Its benefits are already well documented in children and in postlingually deafened adults (Bond et al., 2009; Manrique et al., 1998), whilst there is still some controversy concerning prelingually deafened adolescents and adults. Initial studies on the last two populations showed only limited improvement post-implant for closed-set speech perception tasks and for the recognition of envi-ronmental sounds, with no open-set recognition in most patients. Furthermore, the authors concluded that only a few patients with long-term prelingual deafness could be considered good candidates for CI. This can be attributed to the fact that, if implanted during this phase, prelingually deafened adolescents and adults have passed the ‘sensitive period’ for language development and the ability of the central nervous system to reorganize itself is more limited. Moreover, adolescents and adults with prelingual deafness represent a very heterogeneous group of patients, owing to age at implantation, duration of auditory deprivation, residual hearing, level of language skills, communication modes, and educational experience, all of which can affect post-implant outcomes and this makes it more difficult to decide which option to take. Finally, in adolescents further difficulties are linked to the critical period that they have to face in terms of physical, mental, emotional, and social developments and changes. During the last years, authors have widened prospects in this field via the evalua-tion of further important parameters such as quality of life, personal satisfaction, well-being, schooling, and employment. Thus, despite the limited improvement in speech perception, they were able to show positive effects resulting from cochlear implantation on the quality of life (Zwolan et al., 1996; Klop et al., 2007). However, there are still only a few papers to be found in literature on this topic. Published by Maney Publishing (c) W. S. Maney & Son Limited

Auditory Rehabilitation After Long-Term Deafness

Auditory Rehabilitation After Long-Term Deafness

AUDITORY REHABILITATION AFTER LONG-TERM DEAFNESS

The duration of preexisting profound deafness in patients with bilateral retrocochlear lesions is known to correlate negatively to the extent of auditory restoration after auditory brainstem implantation. There is, therefore, a lack of information regarding the potential of the central auditory system to mediate hearing perception after long-term deafness. The authors evaluated auditory perception in a case of auditory brainstem implantation after 35 years of deafness. Electrically evoked auditory brainstem potentials could be elicited by both stimulus polarities and were consistent with auditory brainstem origin. Discrimination between temporal and spectral patterns in speech could be achieved. This permitted us to distinguish various voice qualities, especially of familiar speakers in quiet surroundings. The potential of the deafferentiated central auditory system to mediate auditory brainstem implant-induced hearing perception even after very long-term deafness has been demonstrated. Those patients with complete dysfunction of Cranial Nerve VIII for a long period may be considered as candidates for auditory brainstem implantation in the future.