L-Ergothioneine slows the progression of age-related hearing loss in CBA/CaJ mice

The naturally occurring amino acid, l-ergothioneine (EGT), has immense potential as a therapeutic, having shown promise in the treatment of other disease models, including neurological disorders. EGT is naturally uptaken into cells via its specific receptor, OCTN1, to be utilized by cells as an antioxidant and anti-inflammatory. In our current study, EGT was administered over a period of 6 months to 25-26-month-old CBA/CaJ mice as a possible treatment for age-related hearing loss (ARHL), since presbycusis has been linked to higher levels of cochlear oxidative stress, apoptosis, and chronic inflammation. Results from the current study indicate that EGT can prevent aging declines of some key features of ARHL. However, we found a distinct sex difference for the response to the treatments, for hearing - Auditory Brainstem Responses (ABRs) and Distortion Product Otoacoustic Emissions (DPOAEs). Males exhibited lower threshold declines in both low dose (LD) and high dose (HD) test groups throughout the testing period and did not display some of the characteristic aging declines in hearing seen in Control animals. In contrast, female mice did not show any therapeutic effects with either treatment dose. Further confirming this sex difference, EGT levels in whole blood sampling throughout the testing period showed greater uptake of EGT in males compared to females. Additionally, RT-PCR results from three tissue types of the inner ear confirmed EGT activity in the cochlea in both males and females. Males and females exhibited significant differences in biomarkers related to apoptosis (Cas-3), inflammation (TNF-a), oxidative stress (SOD2), and mitochondrial health (PGC1a).These changes were more prominent in males as compared to females, especially in stria vascularis tissue. Taken together, these findings suggest that EGT has the potential to be a naturally derived therapeutic for slowing down the progression of ARHL, and possibly other neurodegenerative diseases. EGT, while effective in the treatment of some features of presbycusis in aging males, could also be modified into a general prophylaxis for other age-related disorders where treatment protocols would include eating a larger proportion of EGT-rich foods or supplements. Lastly, the sex difference discovered here, needs further investigation to see if therapeutic conditions can be developed where aging females show better responsiveness to EGT.

Comprehensive Transcriptomic Profiling of m6A Modification in Age-Related Hearing Loss

Age-related hearing loss (ARHL), also known as presbycusis, is one of the most common neurodegenerative disorders in elderly individuals and has a prevalence of approximately 70-80% among individuals aged 65 and older. As ARHL is an intricate and multifactorial disease, the exact pathogenesis of ARHL is not fully understood. There is evidence that transcriptional dysregulation mediated by epigenetic modifications is widespread in ARHL. However, the potential role of N6-methyladenosine (m6A) modification, as a crucial component of epigenetics, in ARHL progression remains unclear. In this study, we confirmed that the downregulation of m6A modification in cochlear tissues is related to ARHL and found that the expression of the m6A methylation regulators Wilms tumour suppressor-1-associated protein (WTAP), methyltransferase-like 3 (METTL3), ALKB homologous protein 5 (ALKBH5) and fat mass and obesity-associated protein (FTO) is decreased significantly at the mRNA and protein levels in ARHL mice. Then, we used methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and RNA sequencing (RNA-Seq) to identify the differentially m6A-methylated genes in the cochlear tissues of ARHL mice. A total of 3438 genes with differential m6A methylation were identified, of which 1332 genes were m6A-hypermethylated and 2106 genes were m6A-hypomethylated in the ARHL group compared to the control group according to MeRIP-seq. Further joint analysis of RNA-Seq and MeRIP-Seq data showed that 262 genes had significant differences in both mRNA expression and m6A methylation. GO and KEGG analyses indicated that 262 unique genes were enriched mainly in the PI3K-AKT signalling pathway. In conclusion, the results of this study reveal differential m6A methylation patterns in the cochlear tissues of ARHL mice, providing a theoretical basis for further study of the pathogenesis of ARHL and potential therapeutic strategies.

Cochleovestibular involvement in patients with Fabry disease: data from the multicenter cohort FFABRY

PURPOSE

Fabry disease (FD) is a lysosomal storage disease responsible for cochleovestibular involvement. Exact prevalence and pathophysiological mechanisms behind ENT affections are still poorly known. Treating FD with enzyme replacement therapy (ERT) does not seem to significantly improve the ENT symptoms, while the impact of migalastat has yet to be determined.

METHODS

We carried out a retrospective multi-centre study on 47 patients from the FFABRY cohort who had an ENT consultation in the context of their FD. The information collected were as follows: clinical examination, videonystagmoscopy, pure-tone speech audiometry, videonystagmography or VHIT (Video Head Impulse Test). Severe hearing loss was defined as greater than 70 dB.

RESULTS

The median age of our cohort was 52 years with a non-negligible proportion of non-classic variants and female carriers. 72.3% of the patients complained of at least one of the following symptoms: hearing loss, tinnitus or vertigo. Pure-tone audiometry was abnormal in 61.7% of the patients (29/47), while speech audiometry was abnormal for 41.7% of the patients. The age of the patients and hypertrophic cardiomyopathy were significantly associated with the existence of an anomaly in pure-tone audiometry results. Severe hearing loss (> 70 dB) was significantly more common in male patients.

DISCUSSION

Hearing loss is particularly frequent in FD and is not limited to classic phenotypes. Close ENT follow-up is essential for Fabry patients to detect those who might benefit from hearing aid. Further studies are needed to define the impact of migalastat on cochleovestibular symptoms.

Cochlear implantation under local anesthesia in 117 cases: patients' subjective experience and outcomes

Purpose

To report the outcomes and the patients’ subjective experience of cochlear implantation (CI) performed under local anesthesia (LA). To describe a new form of intraoperative cochlear monitoring based on the patients subjective sound perception during CI.

Methods

In this retrospective case–cohort study, 117 patients underwent CI under LA with (n = 58) or without conscious sedation (n = 59). Included were primarily elderly patients with elevated risks for general anesthesia and recently patients with residual hearing eligible for electro-acoustic stimulation (EAS) (n = 27), in whom hearing could be monitored during the electrode insertion. A 500 Hz test tone was presented and the patient reported  of subjective changes in loudness, leading to a modification of the insertion. A questionnaire was sent to all patients in which they assessed their subjective experience.

Results

All patients were successfully operated under LA without the need to intraoperatively convert to general anesthesia. 90% of the patients reported that the surgery was a positive experience. The vast majority, 90% of patients were satisfied with the overall treatment and with intraoperative pain management and 84% of the patients would opt for local anesthesia again. Cochlear monitoring by the patients’ subjective sound perception enabled for atraumatic insertions as all EAS patients could hear the test tone up to the end of the surgery.

Conclusions

CI under LA was well tolerated and recommended by the vast majority of patients. In addition, it offers the possibility to monitor the patients’ hearing during the electrode insertion, which may help to prevent insertion trauma.

Cochlear Synaptopathy: A Primary Factor Affecting Speech Recognition Performance in Presbycusis

The results of recent animal studies have suggested that cochlear synaptopathy may be an important factor involved in presbycusis. Therefore, here, we aimed to examine whether cochlear synaptopathy frequently exists in patients with presbycusis and to describe the effect of cochlear synaptopathy on speech recognition in noise. Based on the medical history and an audiological examination, 94 elderly patients with bilateral, symmetrical, sensorineural hearing loss were diagnosed as presbycusis. An electrocochleogram, auditory brainstem responses, auditory cortical evoked potentials, and speech audiometry were recorded to access the function of the auditory pathway. First, 65 ears with hearing levels of 41-50 dB HL were grouped based on the summating potential/action potential (SP/AP) ratio, and the amplitudes of AP and SP were compared between the two resulting groups. Second, 188 ears were divided into two groups: the normal SP/AP and abnormal SP/AP groups. The speech recognition abilities in the two groups were compared. Finally, the relationship between abnormal electrocochleogram and poor speech recognition (signal-to-noise ratio loss ≥7 dB) was analyzed in 188 ears. The results of the present study showed: (1) a remarkable reduction in the action potential amplitude was observed in patients with abnormal SP/AP ratios; this suggests that cochlear synaptopathy was involved in presbycusis. (2) There was a large proportion of patients with poor speech recognition in the abnormal SP/AP group. Furthermore, a larger number of cases with abnormal SP/AP ratios were confirmed among patients with presbycusis and poor speech recognition. We concluded that cochlear synaptopathy is not uncommon among elderly individuals who have hearing ability deficits, and it may have a more pronounced effect on ears with declining auditory performance in noisy environments.

Effectiveness of a programable body-worn digital hearing aid for older adults in a developing country: a randomized controlled trial with a cross-over design

Background

Hearing aids are important assistive devices for hearing rehabilitation. However, the cost of commonly available commercial hearing aids is often higher than the average monthly income of individuals in some developing countries. Therefore, there is a great need to locally produce cheaper, but still effective, hearing aids. The Thai-produced P02 hearing aid was designed to meet this requirement.

Objective

To compare the effectiveness of the P02 hearing aid with two common commercially available digital hearing aids (Clip-II™ and Concerto Basic®).

Methods

A prospective, randomized controlled trial with a cross-over design was conducted from October 2012 to September 2014 in a rural Thai community. There were 73 participants (mean age of 73.7 ± 7.3 years) included in this study with moderate to severe hearing loss who were assessed for hearing aid performance, including probe microphone real-ear measurement, functional gain, speech discrimination, and participant satisfaction with the overall quality of perceived sound and the design of the device.

Results

There were no statistically significant differences in functional gain or speech discrimination among the three hearing aids evaluated (p-value > 0.05). Real-ear measurements of the three hearing aids met the target curve in 93% of the participants. The best real-ear measurement of the hearing aid following the target curve was significantly lower than that of Clip-II™ and Concerto Basic® (p-value < 0.05) at high frequency. However, participants rated the overall quality of sound higher for the P02 hearing aid than that of Clip-II™ but lower than that of Concerto Basic® (p-value > 0.05). Participants revealed that the P02 hearing aid provided the highest satisfaction ratings for design and user-friendliness with statistical significance (p-value < 0.05).

Conclusion

The P02 hearing aid was an effective device for older Thai adults with hearing disabilities. Additionally, its modern design, simplicity of use, and ease of maintenance were attractive to this group of individuals. These benefits support the rehabilitation potential of this hearing aid model and its positive impact on the quality of life of older adults in developing countries.

Trial registration

This study was registered under Clinicaltrial.govNCT01902914. Date of registration: July 18, 2013.

Special Populations in Implantable Auditory Devices: Geriatric

Hearing loss is common in the geriatric population. Most hearing loss is associated with presbycusis or age-related hearing loss, impacting one-third of individuals over 65 years and increasing in prevalence with age. Hearing loss impacts quality of life, psychological health, and cognition. Implantable auditory devices are an exceptional option to improve hearing and quality of life. Various implantable auditory devices have been implemented safely with significant improvement in communication and performance on auditory tasks. Counseling is essential to establishing realistic expectations. Rehabilitation may be required to optimize outcomes and auditory performance with use.

Healthcare Costs for Insured Older U.S. Adults with Hearing Loss

OBJECTIVES

To measure 18-month healthcare cost difference attributable to hearing loss (HL) in older adults.

DESIGN

Matched cohort.

SETTING

Retrospective analysis of administrative healthcare bills of insured older Americans.

PARTICIPANTS

Older U.S. adults with health insurance in 3 cohorts matched based on HL diagnosis using propensity score methods (N=904,750).

MEASUREMENTS

Comparison groups were defined as those with and without HL diagnosis using International Classification of Diseases, Ninth Revision, diagnosis codes from billing records. Outcomes measured include 18-month total healthcare payments and healthcare payments broken down according to payment type (inpatient, outpatient, prescription, hearing services). Three comparison cohorts were examined for these outcomes: individuals covered by Medicare plus supplemental private insurance (Cohort 1, n=782,216), those covered only under Medicare (Cohort 2, n=105,296), and those within the Medicare sample that were dually eligible for Medicare and Medicaid coverage (Subcohort 3, n=17,238). The quality of the propensity score match was examined using standardized differences in means or proportions between all matched covariates, and cost outcomes were analyzed using multiple generalized linear regression models.

RESULTS

Fully adjusted models showed significantly higher 18-month healthcare payments for individuals with a diagnosis of HL without indication of use of hearing services than in those without a HL diagnosis in the 3 samples (payment differences: $3,587 Cohort 1, $3,779 Cohort 2, $4,657 Subcohort 3; all p<.001). Payment differences were also found between individuals with HL and indications of hearing services and those without HL.

CONCLUSION

We observed more than 20% higher total healthcare payments over 18 months for a group of insured individuals with HL regardless of insurance type or hearing services use, indicating that negative health-related effects of HL may increase healthcare use unrelated to HL. Thus, clinical care to ameliorate HL may improve overall health.

Phenotypic Optimization of Urea-Thiophene Carboxamides To Yield Potent, Well Tolerated, and Orally Active Protective Agents against Aminoglycoside-Induced Hearing Loss

Hearing loss is a major public health concern with no pharmaceutical intervention for hearing protection or restoration. Using zebrafish neuromast hair cells, a robust model for mammalian auditory and vestibular hair cells, we identified a urea-thiophene carboxamide, 1 (ORC-001), as protective against aminoglycoside antibiotic (AGA)-induced hair cell death. The 50% protection (HC₅₀) concentration conferred by 1 is 3.2 μM with protection against 200 μM neomycin approaching 100%. Compound 1 was sufficiently safe and drug-like to validate otoprotection in an in vivo rat hearing loss model. We explored the structure-activity relationship (SAR) of this compound series to improve otoprotective potency, improve pharmacokinetic properties and eliminate off-target activity. We present the optimization of 1 to yield 90 (ORC-13661). Compound 90 protects mechanosensory hair cells with HC₅₀ of 120 nM and demonstrates 100% protection in the zebrafish assay and superior physiochemical, pharmacokinetic, and toxicologic properties, as well as complete in vivo protection in rats.

Hearing Assessment after Treatment of Nasopharyngeal Carcinoma with CRT and IMRT Techniques

Objectives. This study analyzed the long-term hearing loss after treatment of primary nasopharyngeal carcinoma to elucidate its causal factors. Methods. Ninety-two nasopharyngeal carcinoma patients were treated with radiotherapy or chemoradiotherapy. Pure tone audiometry was performed before the therapy and annually up to 9 years after completing treatment. The hearing thresholds were corrected for age-related deterioration and compared to the results without adjusting for age. Results. The mean air and bone conduction threshold with and without correction for age-related deterioration differed significantly 2–9 years after completing radiotherapy (p < 0.05). The audiometry results with age correction showed a flattened configuration compared to the results without age correction. The total radiation dose and radiation modality showed a causal relationship with a greater incidence of hearing loss after therapy (p < 0.05). There was more deterioration in the air and bone hearing thresholds with conformal radiotherapy than intensity-modulated radiotherapy (p < 0.001). A radiation dose >72 cGy resulted in more severe hearing loss than <72 cGy (p < 0.05). Conclusion. Hearing loss after completing therapy should be corrected for age-related hearing deterioration to reveal the true extent to which the loss is a therapeutic complication. Both the radiation modality used and the dose were significantly associated with hearing loss.

Contribution of adiponectin and its type 1 receptor to age-related hearing impairment

Age-related hearing impairment (ARHI) is a complex neurodegenerative disorder caused by a combination of environmental and genetic factors. We have reported previously that obesity increases the risk for ARHI, and that plasma levels of adiponectin are associated with ARHI. In the present study, we further explored the role of adiponectin in the pathophysiology of ARHI by investigating the genotypes of ADIPOQ and ADIPOR1, the genes of adiponectin and its type 1 receptor, respectively. A total of 1682 volunteers were enrolled, and their audiological phenotypes were determined according to the z scores converted from their original frequency-specific hearing thresholds. A total of 9 tag-single nucleotide polymorphisms (tagSNPs) in ADIPOQ and 4 tagSNPs in ADIPOR1 were genotyped, and the genotypes were correlated to the audiological phenotypes under the assumption of various inheritance models. Significant associations were identified between certain ADIPOQ tagSNPs and z scores under dominant, codominant, or additive models, whereas no association was identified between ADIPOR1 tagSNPs and z scores. The associations between ADIPOQ tagSNPs and z scores appear to exist only in subjects with specific ADIPOR1 genotypes, indicating an interaction between adiponectin and AdipoR1. Measurement of plasma adiponectin in 736 subjects revealed that ADIPOQ genotypes might exert their effects on hearing levels via modulation of plasma adiponectin levels. Subsequently, we confirmed the expression of AdipoR1 in the inner ear of mice, and demonstrated antiapoptotic effects of adiponectin in cochlear explant cultures. These results provide insights into the physiological function and potential clinical implications of adiponectin against ARHI.

Aging, cognitive load, dementia and hearing loss

Sensorineural systems play a crucial role in the diagnosis, treatment and management of several neurological disorders. The function of the eye and ear represents a unique window for testing various conditions in cognitive decline or dementia. Touch and smell have also been found to be strongly involved in neurodegenerative conditions, and their decline has been significantly associated with the progression of the disease; hence, the idea that restoring sensory function in cognitively impaired adults might enable a significant improvement in their cognitive status, reducing the worldwide incidence and prevalence of dementia. Not all sensorineural 'windows' can benefit equally from the same procedures; however, hearing and vision can certainly gain the most from dependable therapeutic and other diagnostic options. The ear, including the vestibular system, deserves an honored place among the sensory organs in this context due mainly to the sophisticated electrical devices available that have amply demonstrated their effectiveness in treating hearing loss. Restoring an individual's hearing can reduce the cognitive 'load', i.e. the neural activity needed to understand/recognize the spoken word - an activity that becomes more demanding if the brain is obliged to recruit different neural populations to achieve the same performance, as happens in older adults with sensory impairments. The sensory interfaces may also facilitate the early diagnosis of conditions characterized by a lengthy preclinical phase, as well as enabling noninvasive, follow-up procedures to assess the outcome of rehabilitation measures and distinguish physiological brain aging from neurodegenerative disorders. The present study is a brief literature review on the issues and prospects relating to the unique relationship between hearing and cognitive decline, with a general introduction to the main topics before focusing on rehabilitation training with hearing aids and cochlear implants to combat cognitive decline.

Adenosine amine congener as a cochlear rescue agent

We have previously shown that adenosine amine congener (ADAC), a selective A₁ adenosine receptor agonist, can ameliorate noise- and cisplatin-induced cochlear injury. Here we demonstrate the dose-dependent rescue effects of ADAC on noise-induced cochlear injury in a rat model and establish the time window for treatment. Methods. ADAC (25–300 μg/kg) was administered intraperitoneally to Wistar rats (8–10 weeks old) at intervals (6–72 hours) after exposure to traumatic noise (8–16 kHz, 110 dB sound pressure level, 2 hours). Hearing sensitivity was assessed using auditory brainstem responses (ABR) before and 12 days after noise exposure. Pharmacokinetic studies investigated ADAC concentrations in plasma after systemic (intravenous) administration. Results. ADAC was most effective in the first 24 hours after noise exposure at doses >50 μg/kg, providing up to 21 dB protection (averaged across 8–28 kHz). Pharmacokinetic studies demonstrated a short (5 min) half-life of ADAC in plasma after intravenous administration without detection of degradation products. Conclusion. Our data show that ADAC mitigates noise-induced hearing loss in a dose- and time-dependent manner, but further studies are required to establish its translation as a clinical otological treatment.

Changes in the cochlear vasculature and vascular endothelial growth factor and its receptors in the aging c57 mouse cochlea

Introduction. Previous work has shown a strong association between alterations in cochlear vasculature, aging, and the development of presbycusis. The important role of vascular endothelial growth factor (VEGF) and its receptors Flt-1 and Flk-1 in angiogenesis suggests a potential role for involvement in this process. The aim of this study was to characterize vascular structure and VEGF and its' receptors in young and old C57 Mice. Methods. Young (4 weeks, n = 14) and aged (32–36 weeks, n = 14) C57BL/6 mice were used. Hearing was evaluated using auditory brainstem response. Cochleas were characterized with qRT-PCR, immunohistochemistry, and gross histological quantification. Results. Old C57 mice demonstrated significantly decreased strial area, blood vessel number, luminal size, and luminal area normalized to strial area (vascularity). qRT-PCR showed a significant upregulation of Flt-1, a VEGF receptor, in older animals. No differences were found in VEGF-A or Flk-1. Immunohistochemistry did not show any differences in staining intensity or area with age or cochlear turn location. Conclusion. The marked deafness of aged C57 mice could be in part meditated by loss of vascular development and alterations in VEGF signaling.

Unilateral multi-channel cochlear implantation results in significant improvement in quality of life

OBJECTIVES

To investigate the effects of unilateral multi-channel cochlear implant surgery on health-related quality of life and to determine if there is an age-related impact of cochlear implantation on these effects.

DESIGN

Prospective study.

SETTING

Tertiary health-care center.

METHODS

The Short Form-36 survey (SF-36) was administered to determine the health-related quality of life of 283 age-stratified patients before and after cochlear implant surgery.

MAIN OUTCOMES

Precochlear to postcochlear implantation changes in health-related quality of life as determined by the SF-36 questionnaire.

RESULTS

There were significant increases in precochlear and postcochlear implantation scores for 5 of the 8 SF-36 survey domains: vitality, physical role functioning, mental health, emotional role functioning, and social functioning. Significant differences were found between age groups in the domains of social functioning, emotion role functioning, and mental health.

CONCLUSION

Cochlear implant surgery significantly improves health-related quality of life as categorically stratified by the SF-36 questionnaire. These improvements were most evident in the mental health, emotional and social functioning, and physical functioning at work questions of the survey. Cochlear implant recipients younger than 65 years perceive a greater improvement in their level of energy, mental health, and social function compared with those older than 65 years.