Individual Cochlear Implant Research Articles

Systematic review of cochlear implantation in patients with inner ear malformations.

ObjectivesTo evaluate the outcomes of cochlear implantation in patients with severe to profound sensorineural hearing loss due to inner ear malformations (IEMs) when compared to patients without IEMs. We discussed audiological outcomes such as open-set testing, closed-set testing, CAP score, and SIR score as well as postoperative outcomes such as cerebrospinal fluid gusher and incomplete insertion rate associated with cochlear implantation in individuals with IEMs.Data sourcesPubMed, Science Direct, Web of Science, Scopus, and EMBASE databases.Review methodsAfter screening a total of 222 studies, twelve eligible original articles were included in the review to analyze the speech and hearing outcomes of implanted patients with IEMs. Five reviewers independently screened, selected, and extracted data. The “Tool to Assess Risk of Bias in Cohort Studies” published by the CLARITY group was used to perform quality assessment on eligible studies. Systematic review registration number: CRD42021237489.ResultsIEMs are more likely to be associated with abnormal position of the facial nerve, raising the risk of intraoperative complications. These patients may benefit from cochlear implantation, but audiological outcomes may also be less favorable than in individuals without IEMs. Furthermore, due to the risk of cerebrospinal fluid gusher, incomplete insertion of electrodes, and postoperative facial nerve stimulation, surgeons can employ precautionary measures such as preoperative imaging and proper counseling. Postoperative imaging is suggested to be beneficial in ensuring proper electrode placement.ConclusionsCochlear implants (CIs) have the potential to provide auditory rehabilitation to individuals with IEMs. Precise classification of the malformation, preoperative imaging and anatomical mapping, appropriate electrode selection, intra-operative techniques, and postoperative imaging are recommended in this population.

Cochlear Implantation for Patients with a Vestibular Schwannoma: Effect on Tinnitus Handicap.

Background:Tinnitus is a common symptom among individuals with a vestibular schwannoma. In recent years, cochlear implantation, often combined with tumor resection, is an increasingly used option in the management of these patients. The existing literature does not account well for the effect of treatment on tinnitus burden. Thus, this paper reports the effect of cochlear implantation on tinnitus in a cohort of vestibular schwannoma patients.Methods:Individuals with vestibular schwannoma undergoing cochlear implantation were retrospectively reviewed for tinnitus burden, as evaluated by the Tinnitus Handicap Inventory, administered before and after implantation. The outcome measures were total Tinnitus Handicap Inventory score and scores from each of the Tinnitus Handicap Inventory subdomains (functional, emotional, and catastrophic). In addition, the existing literature on tinnitus in cochlear implanted vestibular schwannoma patients was reviewed.Results:Tumor management consisted of simultaneous resection (77%), previous resection (9%), observation (9%) and radiation (5%). Complete Tinnitus Handicap Inventory evaluation was available for 17 patients. After implantation, the median THItotal changed from 18 to 10 (P = .0006), the subdomain THIfunctional from 10 to 3 (P = .006), the THIemotional from 3 to 0 (P = .023) and the THIcatastrophic from 6 to 1 (P = .004). In the scarcely reported tinnitus outcomes in the literature, most but not all cases experienced a decrease in tinnitus.Conclusions:The tinnitus burden is significantly reduced by cochlear implantation in individuals with a vestibular schwannoma. This agrees with findings for other etiologies indicating cochlear implantation and supports the eligibility for hearing rehabilitation with a cochlear implant for this specific group of patients.

Cochlear implants in single-sided deaf recipients: Near normal higher-order processing

ObjectiveSingle-sided deafness (SSD) is a condition where an individual has a severe to profound sensorineural hearing loss in one ear and normal hearing on the contralateral side. The use of cochlear implants in individuals with SSD leads to functional improvements in hearing. However, it is relatively unclear how sounds incoming via the cochlear implant (independent of the hearing ear) are processed and interpreted by higher-order processes in the brain. MethodsScalp electroencephalography and auditory event-related potentials were recorded monaurally from nine experienced single sided cochlear implant users. Speech-in-noise and localisation tests were used to measure functional changes in hearing. Resultscochlear implant use was associated with improvement in speech-in-noise and localisation tests (compared to cochlear implant off). Significant N2 and P3b effects were observed in both cochlear implant and normal hearing ear conditions, with similar waveform morphology and scalp distribution across conditions. Delayed response times and a reduced N2 (but not P3b) effect was measured in the CI condition. ConclusionThe brain is capable of using processes similar to those in normal hearing to discriminate sounds presented to the cochlear implant. There was evidence of processing difficulty in the cochlear implant condition which could be due to the relatively degraded signals produced by the cochlear implant compared to the normal hearing ear. SignificanceUnderstanding how the brain processes sound provided by a cochlear implant highlights how cortical responses can be used to guide implantation candidacy guidelines and influence rehabilitation recommendations.

Evaluating the Decision for Cochlear Implantation in Individuals With Single-Sided Deafness (SSD); Implementing the SSD Consensus Protocol Into Clinical Routine.

To implement a unified testing framework into clinical routine that can be used by adults with single-sided deafness (SSD) to assess alternative treatment options before cochlear implantation. Retrospective data analysis. Tertiary referral center with a large CI program. Thirty four participants underwent the new implemented testing procedure, including a test trial with contralateral routing of the signal (CROS) hearing aids and bone conduction devices (BCD) on a headband, before deciding whether to proceed with cochlear implantation. A test battery was used to assess speech in noise, binaural effects (head shadow, squelch, summation, spatial release from masking), sound localization, and quality of life. For participants that chose a CI, the same test battery was repeated during the 6 and 12 months follow-up appointments. Of the 34 participants involved in the study, 11 were implanted with a CI and finished their 12 month evaluation. Sixteen participants decided to stop after the CROS/BCD trial. In the CI-recipient group, a significant head shadow effect of 5.1 to 7.1 dB was achieved with the CI. Recipients in this group received only a limited benefit with either CROS or BCD before implantation. In the non-CI-recipient group, a significant difference between the CROS and BCD, in favor for the CROS device, was found calculating the head shadow and squelch effect. Localization abilities with the CI improved significantly in the CI-recipient group, even between the 6- and 12-month follow-up appointments. In the non-CI-recipient group, localization was significantly better with the BCD during the trial period. Higher scores were obtained from the speech and spatial categories of the Speech, Spatial, and Qualities of Hearing (SSQ) questionnaire with the CI. No subjective difference could be determined in the non-CI-recipient group. Implementing the unified testing framework into a clinical routine was challenging but provided helpful insight into the best treatment option for each individual.

Successful partial cochlear implantation on a patient with relapsing polychondritis

The author reports on a case of relapsing polychondritis in which partial insertion of a cochlear implant has been successful. A woman with known relapsing polychondritis gave a history of increasingly severe auditory loss of sensorineural type occurring bilaterally. Previous repeated treatments with corticosteroids and immunosuppressive medications had been attempted. A right-sided cochlear implantation with partial electrode array insertion was carried out due to the patient's cochlea being obliterated. The outcome was excellent and the improvement in hearing was maintained. Relapsing polychondritis (RP) is a rarely-seen disorder, the aetiology of which is obscure, but which results in inflammation within cartilage throughout the entire body. The cochlea may become obliterated by this process. Cochlear implantation may be needed in such circumstances. The successful outcome in this case shows a potential role for cochlear implantation in individuals with inner ear disorders produced by immune disorders or relapsing polychondritis.

Evaluating the Long-Term Hearing Outcomes of Cochlear Implant Users With Single-Sided Deafness.

To investigate the long-term outcomes of cochlear implantation in individuals with single-sided deafness (SSD) in terms of speech perception, subjective hearing performance, and sound localization. Thirty-four subjects with SSD were recruited across two large cochlear implant (CI) centers (Antwerp, Belgium and Perth, Australia). The long-term hearing outcomes (between 4 and 10 years of CI use) were evaluated using speech in noise tests, a subjective hearing performance questionnaire (Speech, Spatial and Qualities Questionnaire [SSQ12]), and sound localization tests. Statistically significant improvements were observed in speech perception in noise and sound localization results postoperatively with the use of a CI in comparison to preoperative measurements. Subjective hearing abilities also significantly improved after long-term CI use. Access to binaural hearing is important for subjects with SSD. CI users with SSD experience long-term benefits in speech understanding, sound localization, and quality of life.

The hearing benefit of cochlear implantation for individuals with unilateral hearing loss, but no tinnitus

Conclusion: Cochlear implants improve the hearing abilities of individuals with unilateral hearing loss and no tinnitus. The benefit is no different from that seen in patients with unilateral hearing loss and incapacitating tinnitus.Objective: To evaluate hearing outcomes after cochlear implantation in individuals with unilateral hearing loss and no tinnitus and compare them to those obtained in a similar group who had incapacitating tinnitus.Methods: Six cases who did not experience tinnitus before operation and 15 subjects with pre-operative tinnitus were evaluated with a structured interview, a monosyllabic word test under difficult listening situations, a sound localization test, and an APHAB (abbreviated profile of hearing aid benefit) questionnaire.Results: All subjects used their cochlear implant more than 8 hours a day, 7 days a week. In ‘no tinnitus’ patients, mean benefit of cochlear implantation was 19% for quiet speech, 15% for speech in noise (with the same signal-to-noise ratio in the implanted and non-implanted ear), and 16% for a more favourable signal-to-noise ratio at the implanted ear. Sound localization error improved by an average of 19°. The global score of APHAB improved by 16%. The benefits across all evaluations did not differ significantly between the ‘no tinnitus’ and ‘tinnitus’ groups.

Comparison of the benefits of cochlear implantation versus contra-lateral routing of signal hearing aids in adult patients with single-sided deafness: study protocol for a prospective within-subject longitudinal trial.

BackgroundIndividuals with a unilateral severe-to-profound hearing loss, or single-sided deafness, report difficulty with listening in many everyday situations despite having access to well-preserved acoustic hearing in one ear. The standard of care for single-sided deafness available on the UK National Health Service is a contra-lateral routing of signals hearing aid which transfers sounds from the impaired ear to the non-impaired ear. This hearing aid has been found to improve speech understanding in noise when the signal-to-noise ratio is more favourable at the impaired ear than the non-impaired ear. However, the indiscriminate routing of signals to a single ear can have detrimental effects when interfering sounds are located on the side of the impaired ear. Recent published evidence has suggested that cochlear implantation in individuals with a single-sided deafness can restore access to the binaural cues which underpin the ability to localise sounds and segregate speech from other interfering sounds.Methods/DesignThe current trial was designed to assess the efficacy of cochlear implantation compared to a contra-lateral routing of signals hearing aid in restoring binaural hearing in adults with acquired single-sided deafness. Patients are assessed at baseline and after receiving a contra-lateral routing of signals hearing aid. A cochlear implant is then provided to those patients who do not receive sufficient benefit from the hearing aid. This within-subject longitudinal design reflects the expected care pathway should cochlear implantation be provided for single-sided deafness on the UK National Health Service. The primary endpoints are measures of binaural hearing at baseline, after provision of a contra-lateral routing of signals hearing aid, and after cochlear implantation. Binaural hearing is assessed in terms of the accuracy with which sounds are localised and speech is perceived in background noise. The trial is also designed to measure the impact of the interventions on hearing- and health-related quality of life.DiscussionThis multi-centre trial was designed to provide evidence for the efficacy of cochlear implantation compared to the contra-lateral routing of signals. A purpose-built sound presentation system and established measurement techniques will provide reliable and precise measures of binaural hearing.Trial registrationCurrent Controlled Trials http://www.controlled-trials.com/ISRCTN33301739 (05/JUL/2013)

Auditory Abilities After Cochlear Implantation in Adults With Unilateral Deafness

This pilot study examined speech recognition, localization, temporal and spectral discrimination, and subjective reports of cochlear implant (CI) recipients with unilateral deafness. Three adult male participants with short-term unilateral deafness (<5 yr) participated. All had sudden onset of severe-to-profound hearing loss in 1 ear, which then received a CI, and normal or near normal hearing in the other ear. Speech recognition in quiet and noise, localization, discrimination of temporal and spectral cues, and a subjective questionnaire were obtained over several days. Listening conditions were CI, normal hearing (NH) ear, and bilaterally (CI and NH). All participants had open-set speech recognition and excellent audibility (250-6,000 Hz) with the CI. Localization improved bilaterally compared with the NH ear alone. Word recognition in noise was significantly better bilaterally than with the NH ear for 2 participants. Sentence recognition in various noise conditions did not show significant bilateral improvement; however, the CI did not hinder performance in noise even when noise was toward the CI side. The addition of the CI improved temporal difference discrimination for 2 participants and spectral difference discrimination for all participants. Participants wore the CI full time, and subjective reports were positive. Overall, the CI recipients with unilateral deafness obtained open-set speech recognition, improved localization, improved word recognition in noise, and improved perception of their ability to hear in everyday life. A larger study is warranted to further quantify the benefits and limitations of cochlear implantation in individuals with unilateral deafness.

Cochlear Implantation in a Profoundly Deaf Patient Who also Suffers from Multiple Sclerosis — A Case Study

Outcomes of cochlear implantation in individuals with known central nervous system conditions are varied. Long-standing deafness is also thought to correlate negatively with auditory performance in post-linguistically deaf adult implant users.We present a case study of cochlear implantation in a post-lingual adult having bilateral profound hearing loss for over 30 years in addition to multiple sclerosis unrelated to his deafness. Assessment of benefit in terms of speech-perception ability and quality of life reveal that long-term auditory deprivation and co-incidental multiple sclerosis are not a contraindication for cochlear implantation.

Cochlear implantation in individuals with Usher type 1 syndrome

To analyze the occurrence of the Usher type 1 (USH1) gene mutations in cochlear implant recipients with deaf-blind Usher syndrome, and to assess the potential effect of these genes and other factors on the therapeutic outcome. Case series study of nine patients with the phenotypic diagnosis of USH1. Mutation analysis of four USH1 genes (MYO7A, USH1C, CDH23, and PCDH15) by single strand conformational polymorphism (SSCP) and direct sequencing methods. Pre- and post-implantation audiologic tests including pure tone audiometry, speech perception measures, and qualitative assessment of auditory performance. Nine USH1 patients who received their cochlear implants at the University of Miami Ear Institute, Miami, FL, USA, and at the Department of Cochlear Implants, Great Ormond Street Hospital for Children, London, UK. DNA samples from five of the nine patients were available for mutation analysis. Three of the five patients were found to carry USH1 mutations including two with a truncated mutation in CDH23 and one being a digenic inheritance with mutations in CDH23 and PCDH15. We may have failed to detect mutations in the amplicons analyzed, as neither SSCP nor direct sequencing, even combined, detects all mutations present. Our failure to detect mutations in all five patients may also confirm the genetic heterogeneity of USH1 and additional USH1 loci remain to be mapped. Pre-implantation assessment indicated that all of the subjects were pre-linguistically profoundly deaf, had no consistent response to sound, had varying degrees of auditory-oral habilitation. Age at implantation ranged from 2 to 11 years. There was post-implantation improvement in sound detection and speech recognition measures in closed-set format in all patients. Children implanted at an age of 3 years or less showed good open-set speech perception with lip-reading. All patients are implant users. Those patients who do not show open-set perception still use the cochlear implant as an adjunct of lip-reading or total communication. Testing for mutations in the USH1 genes allows early identification and intervention of children with USH1; timely intervention is important to maximize the development of useful auditory-oral communication skills prior to the onset of the visual impairment.