Preservation of residual hearing after cochlear implant surgery: an exploration of residual hearing function in a group of recipients at cochlear implant units

Preservation of Residual Hearing: Long-Term Results With a Mid-Scala Electrode

OBJECTIVE

The long-term preservation of residual hearing after cochlear implantation has become a major goal over the past few years. The aim of the present study was to evaluate residual hearing in the long-term follow-up using mid-scala electrodes.

METHODS

In this retrospective, single-center study, we collected data from 27 patients who were implanted between 2014 and 2015 with residual hearing in the low-frequency range using a mid-scala electrode. Measurements of the hearing thresholds were carried out directly postoperatively (day 1 after surgery) and in the long-term follow-up 43.7 ± 6.9 months. The calculation of the extent of audiological hearing preservation was determined using the HEARRING group formula by Skarsynski.

RESULTS

Postoperative preservation of residual hearing was achieved in 69.2% of the cases in the low-frequency range between 250 Hz and 1 kHz, of which 89.5% of the patients had frequencies that suggested using electroacoustic stimulation (EAS). In the long-term follow-up, 30.8% of the patients showed residual hearing; however, 57.1% had apparently benefited from EAS.

CONCLUSION

Preservation of residual hearing is feasible in the long term using mid-scala electrodes. Postoperatively, there is over the half of patients who benefit from an EAS strategy. The long-term follow-up shows a certain decrease in residual hearing. However, these results are comparable to studies relating to other types of electrodes. Further research should be conducted in future to better evaluate hearing loss in long-term follow-up, compared to direct postoperative audiological results.

Residual low-frequency hearing after early device activation in cochlear implantation

PURPOSE

The cochlear implant (CI) is a standard treatment for patients with severe to profound hearing loss. In recent years, early device activation of the sound processor after 2-3 days following surgery has been established. The aim of this study is to evaluate the residual hearing of CI patients with substantial preoperative low-frequency hearing after early device activation over a period of 12 months.

METHODS

Results were compared between an early fitted group (EF) with device activation to less than 15 days after CI surgery and a control group (CG) with device activation after 3-6 weeks. In total, 57 patients were divided into EF group (n = 32), and CG (n = 25). Low-frequency residual hearing and speech recognition in quiet and in noise were compared over an observation period of 12 months.

RESULTS

No significant difference (p > 0.05) in the residual low-frequency hearing PTAlow between EF and CG was found, neither preoperatively (EF 33.2 dB HL/CG 35.0 dB HL), nor postoperatively (EF 46.8 dB HL/CG 46.2 dB HL). In both groups, postoperative residual hearing decreased compared to preoperative and remained stable within the first year after CI surgery. Furthermore, both groups showed no significant differences (p > 0.05) in speech recognition in quiet and in noise within the first year.

CONCLUSION

Early device activation is feasible in CI patients with preoperative low-frequency residual hearing, without an additional effect on postoperative hearing preservation.

Finite Element Modeling of Residual Hearing after Cochlear Implant Surgery in Chinchillas

Cochlear implant (CI) surgery is one of the most utilized treatments for severe hearing loss. However, the effects of a successful scala tympani insertion on the mechanics of hearing are not yet fully understood. This paper presents a finite element (FE) model of the chinchilla inner ear for studying the interrelationship between the mechanical function and the insertion angle of a CI electrode. This FE model includes a three-chambered cochlea and full vestibular system, accomplished using µ-MRI and µ-CT scanning technologies. This model's first application found minimal loss of residual hearing due to insertion angle after CI surgery, and this indicates that it is a reliable and helpful tool for future applications in CI design, surgical planning, and stimuli setup.

Teenagers and Young Adults Who Are Deaf or Hard of Hearing: a Snapshot of Acculturation in High School and Post-Secondary Life

OBJECTIVES

The current study investigates acculturation in a group of teenagers and young adults who are deaf or hard of hearing (DHH) and who were raised in an age of early identification, early intervention, advanced audiologic technology, and inclusive education.

DESIGN

The Deaf Acculturation Scale ( Maxwell-McCaw & Zea 2011 ) was administered via online survey to 106 teenagers and young adults (mean ages = 16.87 and 24.65 years, respectively). All participants were alumni of an early childhood program for children who are DHH in the United States learning listening and spoken language skills.

RESULTS

The majority of the participants scored as hearing acculturated (79%), with 1% scoring as deaf acculturated, and 20% as bicultural. Teenagers and adults did not differ significantly on acculturation. Participants who identified as hearing acculturated were less likely to use sign language with their friends, at work, or with their families than those who identified as bicultural.

CONCLUSIONS

These results are in contrast to acculturation patterns reported in other populations of young DHH adults, indicating the need to continue investigating the diversity in cultural values, beliefs, and practices of people who are DHH.

Natural course of residual hearing preservation with a slim, modiolar cochlear implant electrode array

PURPOSE

Understanding residual hearing preservation and its natural course following cochlear implantation is important for developing rehabilitation strategies for hearing loss. However, non-uniform evaluation criteria and varying surgical skills pose challenges in fair comparison of the effect of different electrodes on residual hearing preservation. We compared the effect of a slim modiolar electrode (SME) and a slim straight electrode (SSE), implanted by a single surgeon, on progression of residual hearing using different parameters, based on cross-sectional and longitudinal audiological analyses.

METHODS

Patients with preoperative low-frequency pure-tone average (LFPTA) ≤85 dB at 250 and 500 Hz and who underwent minimally traumatic surgical techniques were included. The progression of residual hearing using threshold shifts, hearing preservation rate according to the HEARRING classification, and maintenance of functional low-frequency hearing potentially qualifying for a hybrid stimulation was analyzed up to five time points throughout the 1-year follow-up period.

RESULTS

Threshold shifts and hearing preservation rates according to the HEARRING classification of the electrodes were comparable from 3 months through 12 months postoperatively. Maintenance of functional low-frequency hearing, required for the usage of a hybrid stimulation, was similar for both electrodes. A substantial proportion of implantees with SME use a hybrid stimulation, resulting in long-term use. However, a difference in the pattern of postoperative residual hearing preservation between the two electrodes is possible, probably due to differences in their physical characteristics and location. Specifically, correlation analysis exhibited that significantly less tight modiolar proximity negatively affect the residual hearing preservation, albeit only at 3 months postoperatively, among patients with the SME.

CONCLUSION

Collectively, both SME and SSE implantation showed favorable residual hearing preservation. Our findings further refine the recently proposed hearing preservation with the SME and suggest that the physical characteristics and location of electrodes, in terms of electrode-to-modiolus distance, could affect loss of acoustic hearing in various ways.

Impact of drug-resistant tuberculosis treatment on hearing function in South African adults: Bedaquiline versus kanamycin

Background

Ototoxicity linked to medications used to treat tuberculosis (TB) remains a global challenge.

Objectives

The aim was to describe the audiological function in a group of adults with drug-resistant tuberculosis (DR-TB) on bedaquiline (G-BDQ) treatment attending a TB hospital in South Africa and compare this with patients on kanamycin (G-KCIN).

Methods

A quantitative paradigm was adopted within a non-experimental retrospective record review design. The sample consisted of 30 records of adults with DR-TB between the ages of 18 and 50 years, recruited from a Tropical Diseases Hospital in South Africa. Data were analysed through both descriptive and inferential statistical measures.

Results

Clear and statistically significant differences in the audiological function were found between the two groups. The group receiving G-KCIN presented with ototoxicity that was clearly demonstrated by sensorineural hearing loss of high-frequency worsening of thresholds in over 73% of the records, which was statistically (p < 0.05) and clinically significant, over the three testing sessions, demonstrating the cumulative effects of dosage. Increased evidence of tinnitus was also found in this group. The group receiving G-BDQ presented with neither statistically (p > 0.05) nor clinically significant changes in hearing thresholds across all frequencies over the same monitoring timeframe. Additionally, only one report (7%) of tinnitus was found in this group.

Conclusion

The results indicating that bedaquiline does not cause hearing loss when compared with G-KCIN highlight the need for increased availability of bedaquiline for the treatment of DR-TB within the South African context, to preserve both the quantity and quality of life of those infected.

Evaluating the Efficacy of Taurodeoxycholic Acid in Providing Otoprotection Using an in vitro Model of Electrode Insertion Trauma

Cochlear implants (CIs) are widely used to provide auditory rehabilitation to individuals having severe to profound sensorineural hearing loss (SNHL). However, insertion of electrode leads to inner trauma and activation of inflammatory and apoptotic signaling cascades resulting in loss of residual hearing in implanted individuals. Pharmaceutical interventions that can target these signaling cascades hold great potential for preserving residual hearing by preventing sensory cell damage. Bile salts have shown efficacy in various regions of the body as powerful antioxidants and anti-inflammatory agents. However, their efficacy against inner ear trauma has never been explored. The objective of this study was to determine whether taurodeoxycholic acid (TDCA), a bile salt derivative, can prevent sensory cell damage employing an in vitro model of electrode insertion trauma (EIT). The organ of Corti (OC) explants were dissected from postnatal day 3 (P-3) rats and placed in serum-free media. Explants were divided into control and experimental groups: (1) untreated controls; (2) EIT; (3) EIT+ TDCA (different concentrations). Hair cell (HC) density, analyses of apoptosis pathway (cleaved caspase 3), levels of reactive oxygen species (ROS) as well as inducible nitric oxide synthase (iNOS) activity and Mitochondrial Membrane Potential (MMP) were assayed. Treatment with TDCA provided significant otoprotection against HC loss in a dose-dependent manner. The molecular mechanisms underlying otoprotection involved decreasing oxidative stress, lowering levels of iNOS, and abrogating generation of cleaved caspase 3. The results of the present study suggest that TDCA provides efficient otoprotection against EIT, in vitro and should be explored for developing pharmaceutical interventions to preserve residual hearing post-cochlear implantation.

Genotype-Phenotype Correlation for Predicting Cochlear Implant Outcome: Current Challenges and Opportunities

The use and utility of cochlear implantation has rapidly increased in recent years as technological advances in the field have expanded both the efficacy and eligible patient population for implantation. This review aims to serve as a general overview of the most common hearing disorders that have favorable auditory outcomes with cochlear implants (CI). Hearing loss in children caused by congenital cytomegalovirus infection, syndromic conditions including Pendred Syndrome, and non-syndromic genetic conditions such as hearing impairment associated with GJB2 mutations have shown to be successfully managed by CI. Furthermore, cochlear implantation provides the auditory rehabilitation for the most common etiology of hearing loss in adults and age-related hearing loss (ARHL) or presbycusis. However, in some cases, cochlear implantation have been associated with some challenges. Regarding implantation in children, studies have shown that sometimes parents seem to have unrealistic expectations regarding the ability of CI to provide auditory rehabilitation and speech improvement. Given the evidence revealing the beneficial effects of early intervention via CI in individuals with hearing disorders especially hearing loss due to genetic etiology, early auditory and genetic screening efforts may yield better clinical outcomes. There is a need to better understand genotype-phenotype correlations and CI outcome, so that effective genetic counseling and successful treatment strategies can be developed at the appropriate time for hearing impaired individuals.

Evaluating the Efficacy of L-N-acetylcysteine and Dexamethasone in Combination to Provide Otoprotection for Electrode Insertion Trauma

BACKGROUND

Electrode insertion trauma (EIT) during cochlear implantation (CI) can cause loss of residual hearing. L-N-acetylcysteine (L-NAC) and dexamethasone (Dex) have been individually shown to provide otoprotection albeit at higher concentrations that may be associated with adverse effects. Objective/Aims: The aim of this study is to determine whether L-NAC and Dex could be combined to decrease their effective dosage.

MATERIALS AND METHODS

The organ of Corti (OC) explants were divided into various groups: 1) control; 2) EIT; 3) EIT treated with different concentrations of Dex; 4) EIT treated with different concentrations of L-NAC; 5) EIT treated with L-NAC and Dex in combination. Hair cell (HC) density, levels of oxidative stress, proinflammatory cytokines and nitric oxide (NO) was determined.

RESULTS

There was a significant loss of HCs in explants subjected to EIT compared to the control group. L-NAC and Dex in combination was able to provide significant otoprotection at lower concentrations compared to individual drugs.

CONCLUSIONS AND SIGNIFICANCE

A combination containing L-NAC and Dex is effective in protecting sensory cells at lower protective doses than each compound separately. These compounds can be combined allowing a decrease of potential side effects of each compound and providing significant otoprotection for EIT.

Exploration of factors influencing the preservation of residual hearing following cochlear implantation

BACKGROUND

 Increasing access to cochlear implants within the resource-constrained South African context calls for careful investigation of all factors that might influence benefit from this technological advancement.

OBJECTIVE

 The aim of this study was to investigate preservation of hearing following cochlear implant surgery and whether a relationship existed between the post-operative hearing findings and certain factors.

METHODS

 Within a quantitative paradigm, a retrospective data review design was adopted where a sample consisting of audiological records from 60 observations and surgical records from two cochlear implant units in South Africa was investigated. These records were selected using purposive sampling and consisted of records from participants ranging from 6 to 59 years. Comparative analysis of unaided audiological test results was pre- and post-operatively performed, where all paitents were implanted with cochlear devices. Factors documented to have a possible influence on post-operative outcomes were examined in an attempt to establish relationships that may exist. Findings were analysed by means of both inferential and descriptive statistics.

RESULTS

 The findings indicated 92% success rate in preservation of residual hearing. There was a direct correlation between surgical techniques, as well as cochlear implant type and the successful hearing findings, in the absence of surgical complications. Other factors explored did not have any negative effect on the hearing findings.

CONCLUSION

 The study findings suggest improved surgical outcomes with enhanced surgical techniques and advanced technology, with a clear negative impact of intraoperative complications on the outcomes.