Update on surgical and nonsurgical treatment options for age-related hearing loss

BACKGROUND

Age-related hearing loss (ARHL) is one of the most common chronic conditions that impacts on everyday life far beyonds speech understanding. Chronic hearing loss has been associated with social isolation, depression, and cognitive decline. Early diagnosis and appropriate treatment are recommended.

OBJECTIVE

To give an overview of surgical and non-surgical treatment options for ARHL and the gap between the high prevalence of ARHL and its inadequate treatment to date.

MATERIAL AND METHODS

A selective literature search was carried out in PubMed.

RESULTS

In case of mild to moderate hearing loss, provision of air conduction hearing aids is still the method of choice as it leads to a large benefit in speech understanding and hearing-specific quality of life, and to a slight improvement in overall quality of life. Implantable middle ear systems are used for the treatment of special types of hearing impairment. In case of severe to profound hearing loss, cochlear implantation should be considered; however, only a small number of older people with hearing loss are supplied with hearing aids or cochlear implants despite the well-known benefits of both. This also applies to high-income countries where the costs are covered by health insurance funds.

CONCLUSION

Considering the low rate of properly treated people with hearing loss, large-scale screening programs, including better counselling of older people, should be developed.

Cochlear Immune Response in Presbyacusis: a Focus on Dysregulation of Macrophage Activity

Age-related hearing loss, or presbyacusis, is a prominent chronic degenerative disorder that affects many older people. Based on presbyacusis pathology, the degeneration occurs in both sensory and non-sensory cells, along with changes in the cochlear microenvironment. The progression of age-related neurodegenerative diseases is associated with an altered microenvironment that reflects chronic inflammatory signaling. Under these conditions, resident and recruited immune cells, such as microglia/macrophages, have aberrant activity that contributes to chronic neuroinflammation and neural cell degeneration. Recently, researchers identified and characterized macrophages in human cochleae (including those from older donors). Along with the age-related changes in cochlear macrophages in animal models, these studies revealed that macrophages, an underappreciated group of immune cells, may play a critical role in maintaining the functional integrity of the cochlea. Although several studies deciphered the molecular mechanisms that regulate microglia/macrophage dysfunction in multiple neurodegenerative diseases, limited studies have assessed the mechanisms underlying macrophage dysfunction in aged cochleae. In this review, we highlight the age-related changes in cochlear macrophage activities in mouse and human temporal bones. We focus on how complement dysregulation and the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 inflammasome could affect macrophage activity in the aged peripheral auditory system. By understanding the molecular mechanisms that underlie these regulatory systems, we may uncover therapeutic strategies to treat presbyacusis and other forms of sensorineural hearing loss.

[Hormonal influence on hearing]

BACKGROUND

Hearing loss leads to impairments in communication, social interactions, and cognitive functions. This renders early treatment particularly important. A causal therapy is not yet available. Human and animal studies have shown that certain hormones can have a positive effect on hearing.

OBJECTIVE

This review provides an overview of the effects of various hormones on hearing and describes the potential benefit for future therapeutic approaches.

MATERIALS AND METHODS

A systematic literature review of reviews dealing with the effects of various hormones on hearing in humans and animals published in PubMed between 2015 and 2020 was conducted.

RESULTS

Hormones may mediate antiapoptotic effects on structure-relevant cells of the cochlea and auditory pathway, and may influence hair cell functionality or the electrolyte balance of the endo- and perilymph. Current research focuses on glucocorticoids; the mineral corticoid aldosterone; the sex hormones estrogen, progesterone, and testosterone; the growth hormones GH (growth hormone) and IGF‑1 (insulin-like growth factor 1); thyroid hormones; and insulin. Study results are still inconsistent at this time, but various hormones appear to represent a possible future treatment option for acute hearing loss. Long-term hormone treatment, which would be necessary particularly in the case of age-related hearing loss, does not currently represent a sensible course of action due to the side effect profile of the systemic treatment/lack of practicable topical application options.

CONCLUSION

The mode of action of hormones is complex. Whether they can be used in the future for individualized treatment of patients with acute hearing impairment requires further investigation.

Translational and interdisciplinary insights into presbyacusis: A multidimensional disease

There are multiple etiologies and phenotypes of age-related hearing loss or presbyacusis. In this review we summarize findings from animal and human studies of presbyacusis, including those that provide the theoretical framework for distinct metabolic, sensory, and neural presbyacusis phenotypes. A key finding in quiet-aged animals is a decline in the endocochlear potential (EP) that results in elevated pure-tone thresholds across frequencies with greater losses at higher frequencies. In contrast, sensory presbyacusis appears to derive, in part, from acute and cumulative effects on hair cells of a lifetime of environmental exposures (e.g., noise), which often result in pronounced high frequency hearing loss. These patterns of hearing loss in animals are recognizable in the human audiogram and can be classified into metabolic and sensory presbyacusis phenotypes, as well as a mixed metabolic+sensory phenotype. However, the audiogram does not fully characterize age-related changes in auditory function. Along with the effects of peripheral auditory system declines on the auditory nerve, primary degeneration in the spiral ganglion also appears to contribute to central auditory system aging. These inner ear alterations often correlate with structural and functional changes throughout the central nervous system and may explain suprathreshold speech communication difficulties in older adults with hearing loss. Throughout this review we highlight potential methods and research directions, with the goal of advancing our understanding, prevention, diagnosis, and treatment of presbyacusis.

Evaluation of the efficacy of hearing aids in older adults: a multiparametric longitudinal study protocol

Background

Prevalence of hearing loss increases with age. Its estimated prevalence is 40–50 % in people over 75 years of age. Recent studies agree that declinein hearing threshold contribute to deterioration in sociality, sensitivity, cognition, and quality of life for elderly subjects.

The aim of the study presented in this paper is to verify whether or not rehabilitation using first time applied Hearing Aids (HA) in a cohort of old people with hearing impairment improves both speech perception in a noisy environment over time and the overall health-related quality of life.

Methods

The monocentric, prospective, repeated measurements, single-subject, clinical observational study is to recruit 100 older adults, first-time HA recipients (≥ 65 years).The evaluation protocol is designed to analyze changes in specific measurement tools a year after the first HA usage in comparison with the evaluation before HA fitting.

Evaluations will consist of multiparametric details collected through self-report questionnaires completed by the recipients and a series of commonly used audiometric measures and geriatric assessment tools. The primary indicator of changes in speech perception in noise to be used is the Italian version of Oldenburg Satz (OLSA) test whereas the indicator of changes in overall quality of life will be the Assessment of Quality of Life (AQoL) and Hearing Handicap Inventory for the Elderly (HHIE) questionnaires. The Montreal Cognitive Assessment (MoCA) will help in screening the cognitive state of the subjects.

Discussion

The protocol is designed to make use of measurement tools that have already been applied to the hearing-impaired population in order to compare the effects of HA rehabilitation in the older adults immediately before first HA usage (Pre) and after 1 year of experience (Post). This broad approach will lead to a greater understanding of how useful hearing influences the quality of life in older individuals, and therefore improves potentials for healthy aging. The data is to be analyzed by using an intrasubject endpoint comparison. Outcomes will be described and analyzed in detail.

Trial registration

This research was retrospectively registered underno. NCT04333043at ClinicalTrials.gov (http://www.clinicaltrials.gov/) on the 26 March 2020. This research has been registered with the Ethics Committee of the Area Vasta Emilia Nord under number 104, date of approval 17/07/2017.

[Hearing and cognition: neurocognitive test batteries in otorhinolaryngology]

BACKGROUND

Hearing and cognition are closely related to each other. Particularly in suboptimal listening situations, cognitive abilities become important to enable speech comprehension. Besides, studies have indicated that hearing impairment is associated with a more rapid mental decline compared to persons with normal hearing. However, hearing loss also has an impact on neurocognitive testing, which is generally based on auditive stimuli. With increasing age, the risk of sensory but also of cognitive impairments increases. So far this comorbidity receives little consideration in otorhinolaryngology.

MATERIALS AND METHODS

The paper presents an overview and evaluation of widely used German neurocognitive test batteries for older patients, with regard to the different test modalities and their focus.

RESULTS

A multitude of different neurocognitive screening tests and detailed test batteries are available, particularly in the field of dementia. So far, sensory deficits have not been considered in neurocognitive testing, neither concerning application nor interpretation. Normative data adapted to the hearing impaired are still missing.

CONCLUSION

With regard to demographic changes and the well-known bias between hearing and cognition, screening of neurocognitive functions should be implemented in basic otorhinolaryngologic diagnostics. More comprehensive test batteries might be useful for research purposes or speech therapy.

Age-dependent alterations of Kir4.1 expression in neural crest-derived cells of the mouse and human cochlea

Age-related hearing loss (or presbyacusis) is a progressive pathophysiological process. This study addressed the hypothesis that degeneration/dysfunction of multiple nonsensory cell types contributes to presbyacusis by evaluating tissues obtained from young and aged CBA/CaJ mouse ears and human temporal bones. Ultrastructural examination and transcriptomic analysis of mouse cochleas revealed age-dependent pathophysiological alterations in 3 types of neural crest-derived cells, namely intermediate cells in the stria vascularis, outer sulcus cells in the cochlear lateral wall, and satellite cells in the spiral ganglion. A significant decline in immunoreactivity for Kir4.1, an inwardly rectifying potassium channel, was seen in strial intermediate cells and outer sulcus cells in the ears of older mice. Age-dependent alterations in Kir4.1 immunostaining also were observed in satellite cells ensheathing spiral ganglion neurons. Expression alterations of Kir4.1 were observed in these same cell populations in the aged human cochlea. These results suggest that degeneration/dysfunction of neural crest-derived cells maybe an important contributing factor to both metabolic and neural forms of presbyacusis.

The aging cochlea: Towards unraveling the functional contributions of strial dysfunction and synaptopathy

Strial dysfunction is commonly observed as a key consequence of aging in the cochlea. A large body of animal research, especially in the quiet-aged Mongolian gerbil, shows specific histopathological changes in the cochlear stria vascularis and the putatively corresponding effects on endocochlear potential and auditory nerve responses. However, recent work suggests that synaptopathy, or the loss of inner hair cell-auditory nerve fiber synapses, also presents as a consequence of aging. It is now believed that the loss of synapses is the earliest age-related degenerative event. The present review aims to integrate classic and novel research on age-related pathologies of the inner ear. First, we summarize current knowledge on age-related strial dysfunction and synaptopathy. We describe how these cochlear pathologies fit into the categories for presbyacusis, as first defined by Schuknecht in the '70s. Further, we discuss how strial dysfunction and synaptopathy affect sound coding by the auditory nerve and how they can be experimentally induced to study their specific contributions to age-related hearing deficits. As such, we aim to give an overview of the current literature on age-related cochlear pathologies and hope to inspire further research on the role of cochlear aging in age-related hearing deficits.

Progression of Hearing Loss in the Aging Population: Repeated Auditory Measurements in the Rotterdam Study

We quantified changes in the auditory acuity of 675 aging adults (mean age 71.1 years, 52.0% female, mean follow-up 4.4 years ± 0.2) of an ongoing cohort study with a pure-tone audiogram and a speech-in-noise test. Generalized estimating equation models were used to study the association between hearing loss and the progression with age, sex, education, cognition, BMI, blood pressure, having type 2 diabetes mellitus, cholesterol ratio, smoking and alcohol consumption. The mean progression of hearing loss was 0.29 and 1.35 dB/year (low and high frequencies). Progression of hearing loss was associated with baseline hearing thresholds. Besides, the presence of type 2 diabetes, smoking, age, sex and time were associated with worse hearing at baseline, but there was no statistical evidence that the tested determinants were associated with progression of hearing loss. This finding indicates that the 4-year progression of hearing loss in older adults in this study is not influenced by the measured determinants. More research with multiple follow-up rounds is desired.

Mitochondrial mutations associated with hearing and balance disorders

Hearing and balance disorders are related to the inner ear and are among the major cause of falls in older adults. Hearing loss that commonly occurs with aging (aka presbyacusis) can result from noise exposure, smoking, ototoxic drugs and genetic factors such as mutations in nuclear and mitochondrial genes. Mutations in mitochondrial DNA (mtDNA) have been reported to play an important role in cell function by providing energy, as well as, cell death (apoptosis). This study aims to systematically review mitochondrial mutations associated with presbyacusis and suggests preventive measurements to improve the quality of life in older adults.

A nonsynonymous mutation in the WFS1 gene in a Finnish family with age-related hearing impairment

Wolfram syndrome (WS) is caused by recessive mutations in the Wolfram syndrome 1 (WFS1) gene. Sensorineural hearing impairment (HI) is a frequent feature in WS and, furthermore, certain mutations in WFS1 cause nonsyndromic dominantly inherited low-frequency sensorineural HI. These two phenotypes are clinically distinct indicating that WFS1 is a reasonable candidate for genetic studies in patients with other phenotypes of HI. Here we have investigated, whether the variation in WFS1 has a pathogenic role in age-related hearing impairment (ARHI). WFS1 gene was investigated in a population sample of 518 Finnish adults born in 1938-1949 and representing variable hearing phenotypes. Identified variants were evaluated with respect to pathogenic potential. A rare mutation predicted to be pathogenic was found in a family with many members with impaired hearing. Twenty members were recruited to a segregation study and a detailed clinical examination. Heterozygous p.Tyr528His variant segregated completely with late-onset HI in which hearing deteriorated first at high frequencies and progressed to mid and low frequencies later in life. We report the first mutation in the WFS1 gene causing late-onset HI with audiogram configurations typical for ARHI. Monogenic forms of ARHI are rare and our results add WFS1 to the short list of such genes.

Behavioral auditory thresholds and loss of ribbon synapses at inner hair cells in aged gerbils

The potential contribution of auditory synaptopathy to age dependent hearing loss was studied in groups of young and old gerbils. The analysis of the number of inner hair cell ribbon synapses in aged gerbils (37.9±3.3months of age) revealed only a relatively small (11-17%) loss in the basal two thirds of the cochlea, while a more pronounced reduction was identified towards the apex (almost 40%) when compared to a group of young gerbils (9.5±3.2months of age). Mean threshold elevation in the old gerbils was around 25dB at 2 and 10kHz. Frequency-specific behavioral thresholds and ribbon synapse counts were not significantly correlated for the middle and basal regions of the cochlea, despite thresholds varying over a 45dB SPL range. This suggests that besides a small age-dependent loss of ribbon synapses, additional cochlear pathologies, most likely a decreased endocochlear potential, contribute to peripheral hearing loss in old gerbils.

Degeneration of stria vascularis in age-related hearing loss; a corrosion cast study in a mouse model

Conclusion With age, in a mouse model, degenerative changes to the capillaries of the stria vascularis are observed. These range from a narrowing of vessel lumen to complete degeneration of strial vessels. Other vascular beds in the cochlea are relatively unchanged with age. Strial capillaries at the cochlear base are significantly more affected than those in mid-apical turns. Objectives Previous work suggests that age-related hearing loss is associated with degenerative changes to cochlear vasculature; the term strial presbyacusis is often cited. This study reports on vascular changes observed in a murine model of presbyacusis, analyzed using corrosion cast techniques. Methods A novel corrosion cast technique was developed to compare cochlear vasculature in control mice (non-presbycusic, CD1) and old (> 6 months) C57BL/6 animals. ABR measures indicated a significant age-related threshold elevation in the C57BL/6 mice. Cochlear vascular casts were imaged using scanning electron microscopy, and vessel degeneration was quantified by measuring capillary diameters. Results Corrosion casts of cochlear vasculature in 6-12 month old C57BL/6 mice reveal significant degeneration of stria vascularis. Other capillary beds (spiral ligament and the spiral limbus) appear unchanged. Comparison of strial capillary diameters reveals significantly more damage in basal/lower-turn regions compared with the cochlear mid-turn.

Slowing the progression of age-related hearing loss: Rationale and study design of the ASPIRIN in HEARING, retinal vessels imaging and neurocognition in older generations (ASPREE-HEARING) trial

BACKGROUND

Age-related hearing loss (ARHL) is a leading cause of disability in the elderly. Low-grade inflammation and microvessel pathology may be responsible for initiating or exacerbating some of the hearing loss associated with aging. A growing body of evidence demonstrates an association of hearing loss with cognitive decline. A shared etiological pathway may include a role of inflammation, alongside vascular determinants. The ASPREE-HEARING study aims to determine whether low-dose aspirin decreases the progression of ARHL, and if so, whether this decrease in progression is also associated with retinal microvascular changes and/or greater preservation of cognitive function.

DESIGN AND METHODS

A three year double-blind, randomized controlled trial of oral 100mg enteric-coated aspirin or matching placebo, enrolling 1262 Australians aged ≥70years with normal cognitive function and no overt cardiovascular disease. The primary outcome is the change in mean pure tone average hearing threshold (decibels) in the better ear, over a 3-year period. Secondary outcomes consist of changes in retinal microvascular indicators, and changes in cognitive function. Participants are recruited from a larger trial, ASPirin in Reducing Events in the Elderly (ASPREE), which is designed to assess whether daily low dose aspirin will extend disability-free life.

DISCUSSION

ASPREE-HEARING will determine whether aspirin slows development or progression of ARHL, and will interrogate the relationship between inflammatory and microvascular mechanisms that may underlie the effects of aspirin on ARHL. This study will improve understanding of the patterns of comorbidity with, and the relationships between, aging and ARHL, alongside modeling the impacts of ARHL.

Deafness, a Social Stigma: Physician Perspective

Hearing is an essential sensory sense of an individual for development of speech which is crucial for verbal communication and personality development. It is the second most common form of disability after loco motor disability in India. Disabling hearing loss is more than 40 dB hearing loss in better ear in a person more than 15 years of age and greater than 30 dB hearing loss in better hearing ear below 14 years of age. WHO estimated 360 million individuals in the world with disabling hearing loss, out of which 91 % are adults and only 9 % are children. Early and accurate identification of birth asphyxia, hyperbilirubinemia, auditory neuropathy Presbyacusis and avoiding noise pollution and discouraging use of mobile phone, tobacco chewing/smoking, in those who are prone to deafness, an intervention is a must to decrease deafness from our society. Deafness prevention can only be possible with mutual cooperation with dedication of different medical and non-medical personnel and also by helping the persons with deafness. We have to focus not only on the children but also on senior citizens as most alarming, up to 40 %, incidence of deafness is in senior citizens above the age of 75 years. Timely cure and preventive measures are essential for better socio-economic state of the country. By helping the persons with deafness, we will not only be doing a great service to the Nation but also to the society at large.

Mitochondrial DNA (mtDNA) haplotypes and dysfunctions in presbyacusis

The aim of this study was to investigate the presence of mitochondrial DNA (mtDNA) alterations and metabolic dysfunctions in patients with presbyacusis, and to discover correlations between presbyacusis and the degree of hearing loss and mitochondrial damage. Seventy patients with presbyacusis were examined, including 40 Egyptian patients and 30 Italian patients. Forty eight normal subjects were included as control group, including 24 Egyptians and 24 Italians. There was no common point mutation, and A1555G, A3243G, A7445G not were detected in any patients or controls. Haplogroup U was significantly common in patients in comparison to controls. Mutation of antioxidant genes (GSTT1, GSTM1) were significantly present in only Italian patients compared to Italian controls.

Role of transient evoked otoacoustic emission beyond screening of hearing impairment: a study of 400 cases

The primary purpose of this study was to investigate the potential role of transient-evoked Otoacoustic emissions (TEOAEs) beyond screening for hearing impairment in different middle/inner ear disorders in 3-65 years age group. Because TEOAEs are present in ears with normal cochlear and middle ear function and typically are absent or reduced in ears with cochlear and/or middle ear disorders of even mild degree. This was a prospective study of four hundred cases. Out of these 364 cases were having problems related to otology and 36 were healthy volunteers who attended the department of otorhinolaryngology of our institute. All the cases were kept in different eight groups and then subjected to Otoacoustic emission testing with the 'GSI AUDIO screener' equipment installed in our ENT department. The data obtained in all groups were analyzed and conclusion was made. TEOAEs is a reliable, simple and cost effective screening technique for hearing disorders with sensitivity varying from 72 to 96.42 % among the study groups and 88 % in composite group comprising all study groups.

Effects of ageing on otoacoustic emission

To study the effects of ageing on otoacoustic emission (OAE) in individuals with normal pure tone audiogram (PTA). Tertiary/Medical College Hospital. Descriptive/Prospective study. We screened healthy individuals: (1) 50 persons in the age group of 20-25 years. (2) Fifty persons in the age group of 45-50 years. (3) Fifty persons in the age group of 55-60 years. (1) The individuals in the age group of 20-25 years showed absent/decreased distortion product OAE (DPOAE) in two cases (2/50) with normal PTA. (2) The individuals in the age group of 45-50 years showed absent/decreased DPOAE in eleven cases (11/50) with normal PTA. (3) The individuals in the age group of 55-60 years showed absent/decreased DPOAE in 47 cases (47/50) with normal PTA. Just like any other organ in the body which exhibits the process of ageing, the cochlea too undergoes similar changes to the ageing process. The DPOAE is the first sign to disappear in presbyacusis. The many factors which hasten the onset of presbyacusis-like nutrition, lifestyle, environment and occupational hazards, infection and illness, drug intake, hereditary etc.; can be modified for prolonging a healthy natural hearing.

Quantitative analysis of the effect of the demographic factors on presbyacusis

BACKGROUND

Presbyacusis is the most common type of hearing loss, often having profound effects on the quality of life in old age. The objectives of this study were: To analyse of the effect of demographic factors on presbyacusis in Sri Lanka.To quantify the effect of non-demographic risk factors on presbyacusis.

METHOD

An observational cross-sectional study was carried out involving all the patients who presented to the National Hospital ENT clinic with hearing loss between April 2007 and April 2010. Patients whose pure-tone audiometry results were suggestive of sensorineural hearing deficit and whose tympanometry testing did not show any middle ear problems were assessed using an interviewer-administered questionnaire.

RESULTS

Among the 567 participants studied, the mean age was 63.4yrs. Fifty eight percent were females. The majority of the patients were from the Colombo district (59.3%), however, participants came from ten districts of Sri Lanka. Most of the study participants (64.2%) were married and living with their partners, but 24.7% were widowed and the rest were either unmarried or divorced. 6.1% had communication difficulties leading to disrupted social relationships and 21% felt that hearing impairment (HI) had adversely affected their psychological well-being. The onset of impaired hearing, as perceived by the patients initially and later confirmed by pure-tone audiometry and tymanometry, had occurred at an average age of 62.9yrs.

CONCLUSION

There was no significant association between presbyacusis and other demographic factors such as gender, education level and marital status. A significant proportion of the participants had been widowed and that fact, too, can reduce their quality of life.

Study of auditory brainstem responses in presbyacusis

The results of auditory brainstem evoked responses in 25 subjects of presbyacusis are compared with 25 age and sex matched controls. Absolute latent periods of wave I through V were significantly prolonged in presbyacusis group. Delayed wave I and no significant change in interwave interval latencies of I-V, III-V and mild shortening of interwave interval of I-III in presbyacusis is observed.