Cochlear Implantation of Bilaterally Deafened Patients with Tinnitus Induces Sustained Decrease of Tinnitus-Related Distress

[Cochlear implant and tinnitus]

Cochlear implant (CI) treatment is now established as a successful standard of care for auditory rehabilitation of profoundly deaf or severe hearing loss patients. CI candidates with tinnitus also benefit from improved health-related quality of life (HRQoL) and tinnitus burden. Current CI indications include bilateral (double-sided) profound hearing loss and deafness (DSD), unilateral (single-sided) deafness (SSD), and asymmetric hearing loss (AHL). The new and expanded indications for cochlear implants result in different healthcare situations, which may also be associated with differences in tinnitus burden before and after CI treatment. In this article, we discuss the prevalence of tinnitus in different patient groups and the influence of CI on tinnitus prevalence and severity in these groups. In addition, further therapeutic options for tinnitus suppression based on the CI principle are presented, including the development of an anti-tinnitus implant (proof of concept).

Changes in Tinnitus Characteristics and Residual Inhibition following Cochlear Implantation: A Prospective Analysis

This study aims to explore the effect of cochlear implantation on tinnitus perception. A prospective study was conducted on 72 adult hearing-impaired patients to evaluate tinnitus perception before and after cochlear implantation, using standardized tinnitus questionnaires (the tinnitus sample case-history questionnaire, tinnitus functional index (TFI), and tinnitus handicap inventory (THI)). A large variety of demographic and hearing- and implant-related data was collected from patient hospital records to explore possible associations with the implantation effect. The prevalence of tinnitus complaints before implantation was 58.3%. The temporary induction or aggravation of tinnitus immediately after surgery was noted in 20% and 46.7% of patients, respectively. When evaluated 3 months after implantation, 60% of tinnitus patients experienced a clinically significant reduction in their complaints; most of the improvements were experienced immediately after activation of the implant. Only the scores for TFI and THI at baseline were found to be significantly correlated with a reduction in TFI scores after implantation. In 80% of tinnitus patients, the tinnitus remained suppressed for some time after taking off the device. The large subset of patients with residual inhibition supports the involvement of central pathophysiological processes in implantation effects on tinnitus, which are explored in this paper.

Tinnitus and Influencing Comorbidities

Numerous studies show that impairments in chronic tinnitus are closely connected with psychosomatic and other concomitant symptoms. This overview summarizes some of these studies. Beyond hearing loss, individual interactions of medical and psychosocial stress factors as well as resources are of central importance. Tinnitus related distress reflects a large number of intercorrelated, psychosomatic influences - such as personality traits, stress reactivity and depression or anxiety - which can be accompanied by cognitive difficulties and should be conceptualized and assessed within a vulnerability-stress-reaction model. Superordinate factors such as age, gender or education level can increase vulnerability to stress. Therefore, diagnosis and therapy of chronic tinnitus be individualised, multidimensional and interdisciplinary. Multimodal psychosomatic therapy approaches aim to address individually constellated medical, audiological and psychological influences in order to sustainably increase the quality of life of those affected. Counselling in the first contact is also indispensable for diagnosis and therapy.

Effects of auditory rehabilitation with cochlear implant on tinnitus prevalence and distress, health-related quality of life, subjective hearing and psychological comorbidities: Comparative analysis of patients with asymmetric hearing loss (AHL), double-sided (bilateral) deafness (DSD), and single-sided (unilateral) deafness (SSD)

Introduction

Auditory rehabilitation with a cochlear implant (CI), in many cases, positively impacts tinnitus. However, it is unclear if the tinnitus-related benefit of CI is equal for patients with various indications for CI. Therefore, this study aimed to determine differences in tinnitus prevalence and distress, health-related quality of life, subjective hearing, perceived stress, and psychological comorbidities between patients diagnosed with asymmetric hearing loss (AHL), single-sided (unilateral) deafness (SSD), and double-sided (bilateral) deafness (DSD) before and six months after cochlear implantation.

Methods

One hundred-one CI candidates were included in this prospective study (39 AHL patients, 23 DSD patients, and 39 SSD patients). The patients completed questionnaires measuring tinnitus distress, health-related quality of life, subjective hearing, perceived stress, and psychological comorbidities before and 6 months after CI.

Results

The prevalence of tinnitus in the entire cohort (80.2% before CI) decreased 6 months after CI to 71.3%. The DSD group had the lowest tinnitus prevalence at both time points. The degree of tinnitus-induced distress decreased significantly in all three groups after CI. Differences in quality of life, subjective hearing, and psychological comorbidities between the groups at the study onset disappeared after CI. Significant correlations existed between anxiety, depression, and tinnitus distress in AHL and SSD but not in DSD patients before and after CI.

Discussion

Our results demonstrate significant differences between the three groups of CI candidates, which might affect the implantation outcome. These differences suggest a need for personalized psychological counseling during the auditory rehabilitation process, focusing on anxiety and depressive symptoms for SSD and AHL patients.

Experience of tinnitus in adults who have severe-to-profound hearing loss: A scoping review

Background

Tinnitus is defined as the subjective perception of sound in the absence of an external stimulus, and tinnitus disorder becomes relevant when it is associated with emotional distress, cognitive dysfunction, and/or autonomic arousal. Hearing loss is recognized as the main risk factor for the pathogenesis of tinnitus. However, clinical guidelines for tinnitus disorder provide little direction for those who have severe-to-profound hearing loss including those who are pre-lingually Deaf. The aim of this scoping review was to catalogue what is known from the existing literature regarding the experience and management of tinnitus in adults who have a severe-to-profound hearing loss.

Summary

A scoping review was conducted following the Preferred Reporting Item for Systematic Reviews and Meta-analysis extension for Scoping Reviews. Records were included if they reported an evaluation of tinnitus in adults who had severe-to-profound hearing loss. The online databases Ovid (MEDLINE, EMBASE and PsycINFO), CINAHL, ProQuest, Scopus, and Google Scholar were searched using the search terms ‘tinnitus’ (as a MESH term) and ‘deaf’ OR ‘profound hearing loss. Thirty-five records met the inclusion criteria for this review and were cataloged according to three major themes: Impact of tinnitus in deaf adults; Primary treatment of tinnitus in deaf adults; and Cochlear implant studies where tinnitus was a secondary outcome. Tinnitus symptom severity was assessed before and after intervention using tinnitus validated questionnaires in 29 records, with six further records using other assessment tools to measure tinnitus severity. Participants using cochlear implants were included in 30 studies. Medication, repetitive transcranial magnetic stimulation (rTMS), electrical promontory stimulation, and behavioral self-control therapy were each reported in single records.

Key messages

This scoping review cataloged the experience, assessment, and treatment of tinnitus in adults who have severe-to-profound hearing loss. It is shown that there is very limited research reported in this field. Although this review included many records, most focused on the provision of cochlear implants for severe-to-profound hearing loss, with assessment and measurement of tinnitus as a baseline or secondary outcome. Largely missing in the literature are empirical studies that seek firstly to understand the nature of the experience of tinnitus by people with no or little residual access to external sound.

Influence of tinnitus annoyance on hearing-related quality of life in cochlear implant recipients

Tinnitus is a common symptom in cochlear implant (CI) recipients. There is no clear evidence of the influence of tinnitus on hearing-related quality of life (QoL) in this population. The aim of this study was to assess the relationship between hearing-related QoL measured by the Speech, Spatial and Qualities of Hearing scale (SSQ12) and tinnitus annoyance or perceived change in tinnitus annoyance after cochlear implantation. The study sample consisted of 2322 implanted adults across France, Germany, Ireland, Italy, the Netherlands, Sweden and the United Kingdom. Information relating to QoL measured using the SSQ12 and tinnitus annoyance and change in tinnitus annoyance, assessed using single-item questions, were collected one or more years post-implantation. The relationship between SSQ12 score and tinnitus annoyance or change in tinnitus annoyance was analysed using linear models adjusted for age and unilateral versus bilateral implants. Tukey pairwise tests were used to compare mean SSQ12 scores across levels of tinnitus annoyance and changes. Tinnitus prevalence was 33.9% post-implantation. Recipients with tinnitus had a significantly lower SSQ12 score than recipients without tinnitus. SSQ scores varied significantly with tinnitus annoyance, age and unilateral versus bilateral implants. Overall, CI recipients who experienced less bothersome tinnitus reported better hearing-related QoL. Healthcare professionals should be aware of the influence of tinnitus on CI recipients’ hearing to manage patient expectations.

Tinnitus suppression with electrical stimulation in adults: long-term follow-up

Objectives

To investigate the long-term effects of cochlear implants as a treatment for patients with severe to profound neurosensory loss associated with severe tinnitus.

Methods

Prospective study in 17 adult patients with severe to profound sensorineural hearing loss associated with severe tinnitus, indicated with a Tinnitus Handicap Inventory (THI) score ≥ 58%, and hyperacusis. Measures were made on hearing, tinnitus, hyperacusis and quality of life up to 5 years after activation of the sound processor of the cochlear implant. It was evaluated by using the disyllabic test, THI, visual analogue scale and Glasgow Benefit Inventory questionnaire.

Results

60 months after cochlear implantation, improvements in loudness and discomfort of tinnitus, speech discrimination and hyperacusis were observed. Subjects perceive an important subjective benefit upon receiving the cochlear implant.

Conclusions

Cochlear implants can be used as treatment for patients with severe to profound sensorineural hearing loss associated with severe tinnitus and hyperacusis with long-term benefits on quality of life and lasting relief of tinnitus.

Hearing Therapy Improves Tinnitus-Related Distress in Mildly Distressed Patients with Chronic Tinnitus and Mild-to-Moderate Hearing Loss: A Randomized-Controlled Cross-Over Design

BACKGROUND

The psychological effects of hearing aids and auditory training are underinvestigated.

OBJECTIVE

To assess the short- and long-term effects of an industry-developed auditory training on tinnitus-related distress, perceived stress, and psychological epiphenomena in patients with chronic tinnitus and mild-to-moderate hearing loss.

METHOD

One-hundred-seventy-seven gender-stratified patients were randomized to an immediate [IIG] or delayed [DIG] intervention group. Following binaural hearing aid fitting, participants completed a CD-enhanced 14-days self-study program. Applying a randomized-controlled cross-over design, psychological measures were obtained at four times: pre-treatment/wait [IIG: t₁; DIG: wait], post-treatment/pre-treatment [IIG: t₂; DIG: t₁], follow-up/post-treatment [IIG: t₃; DIG: t₂], and follow-up [DIG: t₃]. Between- and within-group analyses investigated treatment-related effects and their stability at a 70-day follow-up.

RESULTS

Overall, distress symptom severity was mild. Unlike the DIG, the IIG showed significant improvements in tinnitus-related distress. Some psychological epiphenomena, notably anxiety, slightly improved in both groups. Within-group analyses demonstrated the stability of the tinnitus-distress-related effects, alongside uncontrolled improvements of perceived stress and mood-related symptoms at follow-up.

CONCLUSIONS

The investigated hearing therapy lastingly improves tinnitus-related distress in mildly distressed patients with chronic tinnitus and mild-to-moderate hearing loss. Beneficial psychological knock-on effects deserve further investigation.

Psychophysiological treatment of chronic tinnitus: A review

Subjective chronic tinnitus consists of a more or less continuous perception of sound in the absence of a corresponding acoustic source, which can lead to various psychological problems like depression, anxiety, attentional deficits and sleep disturbances. The prevalence is 10%-15% of the general population. Various therapy and management options have been proposed, but outcomes vary, and no generally accepted cure exists. In this review, the coherence of the most frequently used aetiological models shall be evaluated, and the efficacy of several treatment options will be discussed. With respect to tinnitus treatments, we focus on controlled studies and meta-analyses. Although there are some therapies that outweigh placebo effects such as cognitive behavioural therapy, neurofeedback or neuromodulation techniques, they mainly target secondary symptoms and not the tinnitus tone itself. Furthermore, positive treatment effects only seem to last for a limited period of time. We conclude that long-lasting combination therapies such as neurofeedback of auditory cortex inhibitory EEG signatures, cognitive therapy and sound-tactile stimulation may provide more efficient outcomes if they target the intensity of the tinnitus tone itself and not only secondary psychological symptoms.

Too Blind to See the Elephant? Why Neuroscientists Ought to Be Interested in Tinnitus

A curative therapy for tinnitus currently does not exist. One may actually exist but cannot currently be causally linked to tinnitus due to the lack of consistency of concepts about the neural correlate of tinnitus. Depending on predictions, these concepts would require either a suppression or enhancement of brain activity or an increase in inhibition or disinhibition. Although procedures with a potential to silence tinnitus may exist, the lack of rationale for their curative success hampers an optimization of therapeutic protocols. We discuss here six candidate contributors to tinnitus that have been suggested by a variety of scientific experts in the field and that were addressed in a virtual panel discussion at the ARO round table in February 2021. In this discussion, several potential tinnitus contributors were considered: (i) inhibitory circuits, (ii) attention, (iii) stress, (iv) unidentified sub-entities, (v) maladaptive information transmission, and (vi) minor cochlear deafferentation. Finally, (vii) some potential therapeutic approaches were discussed. The results of this discussion is reflected here in view of potential blind spots that may still remain and that have been ignored in most tinnitus literature. We strongly suggest to consider the high impact of connecting the controversial findings to unravel the whole complexity of the tinnitus phenomenon; an essential prerequisite for establishing suitable therapeutic approaches.

The Effect of Cochlear Implantation on Tinnitus and Quality of Life: A Systematic Review and Meta-analysis

OBJECTIVE

To ascertain the effect of cochlear implantation (CI) on tinnitus and quality of life.

DATABASES SOURCES

PubMed, Scopus, Web of Science, and Cochrane Library were searched through August 21, 2020. Search strategies used a combination of subject headings (e.g., MeSH in PubMed) and keywords for the following two concepts: cochlear implantation and tinnitus.

STUDY SELECTION

English articles reporting on pre-intervention tinnitus-related patient-reported outcome measures (e.g., Tinnitus Handicap Inventory [THI], Tinnitus Questionnaire [TQ], Visual Analogue Scale [VAS] for loudness) and quality of life measures (e.g., Nijmegen Cochlear Implantation Questionnaire [NCIQ] and Hospital Anxiety and Depression Scale [HADS]) for CI recipients were included.

DATA EXTRACTION

Demographics, baseline, and follow-up data.

DATA SYNTHESIS

Total of 27 articles reporting on 1,285 patients (mean age 54.5 years, range 14-81) were included. Meta-analysis of all tinnitus-related measures demonstrated improvement following implantation, with a mean difference of -23.2 [95% CI: -28.8 to -17.7], -12.6 [95% CI: -17.5 to -7.8], and -4.5 [95% CI: -5.5 to -3.4] (p < 0.05 for all) for THI, TQ, and VAS, respectively. NCIQ increased by 12.2 points [95% CI: 8.2-16.2] (p < 0.05), indicating improved quality of life among CI recipients. Psychological comorbidities were also ameliorated, as evidenced by reductions in HADS depression (-1.7 [95% CI: -2.4 to -0.9]) and anxiety (-1.3 [95% CI: -2.1 to -0.5]) (p < 0.05 for both) scores.

CONCLUSION

Following CI, patients reported significant improvement in tinnitus via several validated questionnaires. Additional benefits include improved quality of life and reduction in psychological comorbidities.

Challenges of Cochlear Implantation in Intralabyrinthine Schwannoma Patients: Surgical Procedures and Auditory Outcome

Intralabyrinthine schwannoma (ILS) is a rare benign tumor of the inner ear potentially causing unilateral sensorineural hearing loss and vertigo. This study evaluated the outcome of one surgical session comprising microsurgical ILS resection and cochlear implantation in terms of surgical feasibility, complications, and auditory outcome. Ten clinically and histologically confirmed ILS patients included in this study (three women and seven men; mean age 56.4 ± 8.6) underwent surgery between July 2015 and February 2020. Eight patients had intracochlear tumor location; the remaining two had vestibulocochlear and intravestibular ILS. One of the three following methods was used for tumor removal: an extended cochleostomy, subtotal cochleoectomy, or a translabyrinthine approach. Although negligible improvement was observed in two of the patients, two patients were lost to follow-up, and one opted out from using CI, the speech perception of the five remaining ILS patients improved as per the Freiburg Monosyllable Test (FMT) from 0% before surgery to 45– 50% after the implantation. Our study supports the presented surgical approach’s feasibility and safety, enabling tumor removal and hearing restoration shortly after surgery.

Improvement of Working Memory and Processing Speed in Patients over 70 with Bilateral Hearing Impairment Following Unilateral Cochlear Implantation

Several studies demonstrated the association of hearing disorders with neurocognitive deficits and dementia disorders, but little is known about the effects of auditory rehabilitation on the cognitive performance of the elderly. Therefore, the research question of the present study was whether cochlear implantation, performed in 21 patients over 70 with bilateral severe hearing impairment, could influence their cognitive skills. The measuring points were before implantation and 12 months after the first cochlear implant (CI) fitting. Evaluation of the working memory (WMI) and processing speed (PSI) was performed using the Wechsler Adult Intelligence Scale 4th edition (WAIS-IV). The audiological assessment included speech perception (SP) in quiet (Freiburg monosyllabic test; FMT), noise (Oldenburg sentence test; OLSA), and self-assessment inventory (Oldenburg Inventory; OI). Twelve months after the first CI fitting, not only the auditory parameters (SP and OI), but also the WMI and PSI, improved significantly (p < 0.05) in the cohort. The presented results imply that cochlear implantation of bilaterally hearing-impaired patients over 70 positively influences their cognitive skills.

The Neural Bases of Tinnitus: Lessons from Deafness and Cochlear Implants

Subjective tinnitus is the conscious perception of sound in the absence of any acoustic source. The literature suggests various tinnitus mechanisms, most of which invoke changes in spontaneous firing rates of central auditory neurons resulting from modification of neural gain. Here, we present an alternative model based on evidence that tinnitus is: (1) rare in people who are congenitally deaf, (2) common in people with acquired deafness, and (3) potentially suppressed by active cochlear implants used for hearing restoration. We propose that tinnitus can only develop after fast auditory fiber activity has stimulated the synapse formation between fast-spiking parvalbumin positive (PV⁺) interneurons and projecting neurons in the ascending auditory path and coactivated frontostriatal networks after hearing onset. Thereafter, fast auditory fiber activity promotes feedforward and feedback inhibition mediated by PV⁺ interneuron activity in auditory-specific circuits. This inhibitory network enables enhanced stimulus resolution, attention-driven contrast improvement, and augmentation of auditory responses in central auditory pathways (neural gain) after damage of slow auditory fibers. When fast auditory fiber activity is lost, tonic PV⁺ interneuron activity is diminished, resulting in the prolonged response latencies, sudden hyperexcitability, enhanced cortical synchrony, elevated spontaneous γ oscillations, and impaired attention/stress-control that have been described in previous tinnitus models. Moreover, because fast processing is gained through sensory experience, tinnitus would not exist in congenital deafness. Electrical cochlear stimulation may have the potential to reestablish tonic inhibitory networks and thus suppress tinnitus. The proposed framework unites many ideas of tinnitus pathophysiology and may catalyze cooperative efforts to develop tinnitus therapies.

The effect of tinnitus on hearing-related quality of life outcomes in adult cochlear implant recipients

OBJECTIVE

To describe the effect of tinnitus distress on the hearing-related quality of life (QoL) outcomes over time in adult cochlear implant (CI) recipients.

DESIGN

A retrospective, longitudinal study of adult CI recipients was conducted. Hearing-related QoL and tinnitus distress were assessed using the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Tinnitus Reaction Questionnaire (TRQ) preoperatively and at 6-months, 12-months and >24-month postoperatively. The association between tinnitus distress and hearing-related QoL outcomes over time was investigated. Furthermore, 13 potential predictive factors were identified from the retrospective dataset. Multiple regression analyses were performed to identify variables that influence hearing-related QoL outcomes over time.

STUDY SAMPLE

The study sample included 210 adult (≥18 years) CI recipients implanted between 2001 and 2017.

RESULTS

Lower tinnitus distress and younger age at implantation were significant predictors of better hearing-related QoL in adult CI recipients. A significant reduction in tinnitus distress up to two years post-implantation was found, as well as greater tinnitus distress correlating with poorer hearing-related QoL outcomes.

CONCLUSION

Tinnitus distress negatively affects the hearing-related QoL outcomes of adult CI recipients. Tinnitus distress and age at implantation were found to be significant predictors of hearing-related QoL when controlling for other predictive factors.

Advances in electrical stimulation-based therapy for tinnitus

Tinnitus is a phantom percept of noise heard only by the affected person. The principal problem of persons suffering from tinnitus is the inability to deflect their attention from the phantom sound, resulting in insomnia and problems with concentration, followed by significant health issues. To date, no therapy would relieve patients from the phantom sound. Instead, commonly used therapeutic approaches for tinnitus aim primarily at the reduction of tinnitus-induced distress and are based on various tinnitus habituation methods. Our project aims to quench the tinnitus percept using an implant. To develop such an implant, this research group joined the INTAKT network initiated by the German Federal Ministry of Education and Research and dedicated to the development of smart implants. During this still ongoing, prospective clinical study, the efficacy of two protocols using electrical stimulation is assessed for tinnitus silencing. The electrical stimulation used in the presented study is non-invasive and applied on three consecutive days in the form of short sessions. In a sample of 48 subjects, following three stimulation sessions, 48% of patients reported a significant reduction of tinnitus loudness; 10% reported a brief increase of tinnitus loudness, and 42% stated no change. In one case, the first course of stimulation led to the total distinguishing of tinnitus. On average, the stimulation did not affect the grade of tinnitus-induced distress during the time of measurement. Our current results prompt us to broaden our investigations, expand the subject sample, and further optimize the stimulation conditions.

Single-centre experience and practical considerations of the benefit of a second cochlear implant in bilaterally deaf adults

Purpose

Bilateral cochlear implant (CI) implantation is increasingly used in the auditory rehabilitation of bilaterally deafened adults. However, after successful unilateral implantation, objective patient counselling is essential.

Methods

We investigated the extra benefit of a second CI in adults in terms of health-related quality of life, tinnitus, stress, anxiety, depression, quality of hearing, and speech recognition. Hearing ability was assessed by using the Freiburg monosyllable speech discrimination test (FB MS) and the Oldenburg sentence test with azimuth variations. In a prospective patient cohort, we administered validated questionnaires before a CI, after a first CI and after a second CI implantation.

Results

The study included 29 patients, made up of nine women and 20 men. The median time between the first and the second implantation was 23 months. The mean total NCIQ score and TQ before a CI improved significantly after both implantations. Stress, anxiety, and depression were stable over time and were not significantly affected by CI implantations. Speech recognition with noise significantly improved after the first and again after the second CI. Correlation analysis showed a strong connection between auditory performance and HRQoL.

Conclusion

We demonstrated that a unilateral CI benefitted many fields and that the second sequential CI leads again to additional improvement. Bilateral CI implantation should, therefore, be the standard form of auditory rehabilitation in deafened adults.

Long-term Benefit of Unilateral Cochlear Implantation on Quality of Life and Speech Perception in Bilaterally Deafened Patients

OBJECTIVE

Cochlear implantation (CI) is a common treatment modality for unilaterally and bilaterally deafened patients as well as patients with severe to profound hearing loss. The aim of our study is the complex evaluation of the improvement and influence of health related quality of life (HRQoL) and auditory performance in cochlear implant patients during a long-term follow-up.

METHODS

Sixty-one bilaterally, postlingually deafened patients with unilateral CI were included in this prospective study. Assessment tools for auditory performance and HRQoL included the Freiburg Monosyllabic Speech test, Oldenburg Inventory (OI) questionnaire, Nijmegen Cochlear Implant Questionnaire (NCIQ) and 36-item Short Form Survey (SF-36). Data were collected before CI, at 6, 12, and 24 months postoperatively.

RESULTS

The assessment tools for speech perception yielded a statistically significant improvement in the Freiburg Monosyllabic Speech test scores and of all subdomain scores of the OI during the 6-month follow-up period. The subdomain scores of the NCIQ and the psychological score of the SF-36 also improved significantly during this follow-up period. All results remained stable thereafter during the 12- and 24-month follow-up. There was a statistically significant correlation between subjective speech perception and HRQoL after CI.

CONCLUSION

This is the first prospective study to show results in regard to speech perception and HRQoL and their correlation during a 2-year follow-up after unilateral CI in bilaterally deafened patients. Our results for speech perception and HRQoL showed a significant improvement during the 6-month follow-up that remained stable thereafter during a 24-month follow-up, even after finishing the hearing rehabilitation program.

[Hearing rehabilitation with cochlear implants and cognitive abilities]

The relevance of assessing cognitive functioning is increasing against the background of the continuing demographic changes. Up to a few years ago the focus was on the effects of cochlear implantation in children born deaf in comparison to healthy individuals. Currently, the question arises whether hearing rehabilitation in the elderly, e.g. by postlingual cochlear implantation, has a protective effect on cognitive functioning and therefore on the risk of onset of dementia. This review describes the association of cognitive functioning with hearing disorders and cochlear implantation. Historical aspects of intelligence testing are illustrated. Knowledge on cognitive aspects in elderly persons with hearing disorders and cochlear implants is rare in the currently available literature. Initial findings indicate a positive correlation between hearing improvement and cognitive functioning. Further studies are urgently required in order to elucidate appropriate guidelines for the treatment of patients with cognitive deficits and hearing impairment.

One-Year Results for Patients with Unilateral Hearing Loss and Accompanying Severe Tinnitus and Hyperacusis Treated with a Cochlear Implant

OBJECTIVE

To show that patients with unilateral hearing loss (UHL), with one ear fulfilling cochlear implant (CI) indication criteria, and an additional severe tinnitus handicap can be treated effectively with a CI.

METHOD

A prospective multi-centre study was conducted in five Spanish centres. Sixteen adult patients with UHL and a mean Tinnitus Handicap Inventory (THI) score of at least 58 were implanted. The study design included repeated within-subject measures of quality of life (Health Utility Index Mark 3 [HUI3]), tinnitus (THI, Visual Analogue Scale [VAS] on tinnitus loudness), hearing (Speech, Spatial, and Qualities of Hearing Scale- [SSQ]), and hyperacusis (Test de Hipersensibilidad al Sonido [THS]) up to 12 months after the initial CI fitting.

RESULTS

Group data showed significant subjective benefit from CI treatment: the preoperative HUI3 total utility score of 0.45 went up to 0.57 at 6 months and 0.63 at 12 months; the preoperative THI total score of 75 decreased to 40 at 6 months and 35 at 12 months. The preoperative tinnitus loudness VAS score of 8.2 decreased to 2.4 at 6 months and 2.2 at 12 months with the implant "On" and to 6.7 at 6 months and 6.5 at 12 months with the implant "Off." The preoperative THS total score of 26 decreased to 17 at 12 months. The preoperative SSQ total score of 4.2 increased to 5.1 at 6 months and 6.3 at 12 months. No unanticipated adverse events were reported during the study period. At 12 months after CI activation all subjects (except 1 subject who used the device 6 days a week) wore their devices all day and every day. The primary reason for CI use was split evenly between tinnitus suppression (n = 6) and both hearing and tinnitus (n = 6).

CONCLUSION

A CI should be considered as a treatment option in patients with UHL and a concomitant severe tinnitus handicap. However, appropriate counselling of candidates on the anticipated risks, benefits, and limitations that are inherent to cochlear implantation is imperative.

Preparation, characterization and application research of a sustained dexamethasone releasing electrode coating for cochlear implantation

Cochlear inflammatory response after cochlear implantation (CI) is an important mechanism for implantation trauma and hearing loss. The hearing loss was also caused by damage to auditory hair cells (HCs), whereas ion homeostasis within the cochlea can ensure survival of HCs. In our study, pure hyaluronic acid (HA) was crosslinked with 1, 4-butanediol diglycidyl ether (BDDE) and the successful preparation of the cross-linked hydrogel (CHA) was confirmed by rheological characteristics and FTIR spectra. Artificial perilymph (APL) was prepared to simulate the ion homeostasis microenvironment within scala tympani of human cochlear, and served as the major component of artificial perilymph soaked CHA (APL-CHA). The conductivity experiment indicated that APL-CHA is more suitable to the requirements of the electrical conductivity in scala tympani. The electrode coating process found that the extrusion coating method have advantages of controllable adhesive capacity of APL-CHA, uniform coating thickness and smooth surface as compared to common method. Due to CI surgery application requirement, optimization of coating process was selected as follows: extrusion coating method, degree of 3.6 vol%, pinhole diameter of 32G (110 μm), pressure of 200 ± 15.81 Psi. Controlled dexamethasone 21-phosphate sodium salt (DSP) release of 20 days could be demonstrated using the hydrogel filled reservoir via a validated HPLC method. The morphological structure of CHA showed different sizes of porous structure among APL-CHA provided structural basis for drug delivery. L929 fibroblasts culture and Spiral Ganglion Neuron Explants culture results revealed that APL-CHA possesses fine biological compatibility. APL-CHA shows a promising application in CI surgery and has great potential in preventing hearing loss with well simulation of ion homeostasis within the cochlear, local DSP delivery for target anti-inflammatory, approximate conductivity within the scala tympani and optimization of electrode coating process.