Hearing loss in people with HIV/AIDS and associated factors: an integrative review

Peripheral Auditory Function in Tanzanian Children Living With HIV With Clinically Normal Hearing

IMPORTANCE

Despite normal audiometry, adults living with HIV have lower distortion product otoacoustic emissions (DPOAEs) compared with HIV-negative controls, but the degree of these differences in children living with HIV is unknown. If subclinical auditory deficits are present, results could affect developmental outcomes in children living with HIV (CLWH).

OBJECTIVE

To compare DPOAEs and auditory brainstem responses (ABR) between 2 age- and sex-matched groups of younger children with normal audiometry, 1 infected with HIV and the other uninfected.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study in an infectious disease center in Dar es Salaam, Tanzania. Participants included 340 Tanzanian children aged 3 to 9 years with clinically normal hearing, type A tympanograms bilaterally, and air-conduction thresholds of 20 dB HL or less from 0.5 to 8 kHz. Participants in the cohort repeated testing approximately every 6 months (approximately 2.2 sessions per participant) for a total of 744 total observations. Data were analyzed from March 2020 to January 2022.

MAIN OUTCOMES AND MEASURES

DPOAE amplitudes from 1.5 to 8 kHz using an f2 to f1 ratio of 1.2 and L1/L2 values of 65/55 dB sound pressure level and click-evoked ABR using a slow (21.1/s) and fast (61.1/s) click rate.

RESULTS

A total of 141 CLWH (70 female participants [49.3%]; mean [SD] age, 7.24 [1.67] years) and 199 HIV-negative individuals (99 female participants [49.7%]; mean [SD] age, 7.26 [1.44] years) participated in the study. The groups did not differ significantly in age, static immittance, or air-conduction thresholds. HIV status was independently associated with approximately 1.4 dB (95% CI, -3.28 to 0.30 dB) to 3.8 dB (95% CI, 6.03 to -1.99 dB) lower DPOAE amplitudes at 6 and 8 kHz bilaterally and 0.28 μV (95% CI, 0.01 to 0.33 μV) lower ABR wave V amplitudes in the right ear.

CONCLUSIONS AND RELEVANCE

Consistent with previous findings in young adults, CLWH had slightly, but reliably, lower DPOAEs and ABR wave V amplitudes than HIV-negative controls. The magnitude of these differences was small, but results suggest an early and consistent association between HIV infection or treatment and outer hair cell and auditory brainstem responses in children as young as 3 years. These subclinical changes suggest tracking both auditory function and development outcomes in CLWH is warranted.

Hearing impairment in children living with HIV in Haiti

OBJECTIVE

To identify the prevalence of hearing impairment and associated risk factors in children living with human immunodeficiency virus (HIV) in Haiti.

METHODS

A validated smartphone-based platform with pure-tone audiometry was used to screen 341 HIV-infected children for hearing impairment in Port-au-Prince, Haiti from March 2019 to September 2020. If screening was failed, a more comprehensive pure-tone audiometric evaluation was administered. Demographic, otologic, and HIV-related data were obtained through caregiver surveys and medical charts. Statistical analysis included univariate and multivariate logistic regression.

RESULTS

Sixty (18%) of 341 HIV-infected children (ages 7-18 years) had hearing impairment. Of those failing their hearing assessment, 17 (28%) had moderate and 5 (8%) had severe or profound hearing loss. Hearing impairment was associated with frequent ear infections (OR 3.37; 95% CI 1.76-6.46; p < 0.001) and family history of hearing loss (OR 5.12; 95% CI 2.14-12.23; p = 0.001) but not viral load (OR 1.00; 95% CI 0.73-1.02; p = 0.28) or antiretroviral therapy duration (OR 0.96; 95% CI 0.79-1.17; p = 0.66). Only 35% of caregivers correctly perceived their child's hearing loss.

CONCLUSIONS

Hearing impairment occurs at a higher prevalence in HIV-infected children in Haiti than what is expected for those living without HIV. Frequent ear infections were significantly associated with hearing loss while antiretroviral therapy duration was not. Despite their potential ototoxicity, antiretroviral therapies should be continued and may decrease incidence of otitis media. Low caregiver perception of hearing loss emphasizes the need for routine hearing screening for HIV-infected children.

Cochleovestibular findings linked to COVID-19: A scoping review for clinical care planning in South Africa

Background

On 30 January 2020, the World Health Organization (WHO) officially declared an outbreak of the coronavirus disease 2019 (COVID-19) to be a global health emergency. Research has focused on the impact and response to life-threatening symptoms of COVID-19 across the lifespan; however, there is a need to investigate the effects of COVID-19 on the cochleovestibular system, as viral infections are known to impact this system. This is particularly important for contexts where resources are limited and prioritisation of resources requires strong risk versus benefit evaluations.

Objective

Therefore, the purpose of this scoping review was to investigate published evidence on the impact of COVID-19 on the cochleovestibular system across the lifespan in order to allow for strategic clinical care planning in South Africa, where capacity versus demand challenges exist.

Methods

Electronic bibliographic databases such as CINAHL, EBSCOHost, MEDLINE, ProQuest, PubMed, Scopus and ScienceDirect were searched for peer-reviewed publications between January 2020 and January 2022. These had to be published in English and related to the impact of COVID-19 on the cochleovestibular system, where the question was: ‘what evidence has been published on the impact of COVID-19 on the cochleovestibular system?’ Review selection and characterisation was performed by the researcher with an independent review by a colleague using pretested forms.

Results

Of a total of 24 studies that met the inclusion criteria, the current scoping review revealed limited conclusive published evidence linking COVID-19 to permanent hearing function symptoms. Current evidence supports the possibility of COVID-19, similar to other viral infections in adults, impacting the cochleovestibular system and causing tinnitus, vertigo and sudden sensorineural hearing loss (SSNHL), with the symptoms being generally temporary and resolving either partially or completely following therapy with steroids, with very inconclusive findings in the paediatric population.

Conclusion

These findings raise global implications for properly designed studies, which include longitudinal follow-up of cases across the lifespan, examining this link with some focus on establishing the pathophysiologic mechanisms at play as well. In the meanwhile, current findings raise the value of polymerase chain reaction (PCR) testing for all patients presenting with unexplained cochleovestibular symptoms during the pandemic, as these may be the only presenting symptoms indicating COVID-19, thus requiring careful treatment and management.

Peripheral Auditory Function in Young HIV-Positive Adults With Clinically Normal Hearing

OBJECTIVE

Little is known about peripheral auditory function in young adults with HIV, who might be expected to show early evidence of hearing loss if HIV infection or treatment does affect peripheral function. The goal of this study was to compare peripheral auditory function in 2 age- and gender-matched groups of young adults with clinically normal hearing with and without HIV.

STUDY DESIGN

Matched cohort study with repeated measures.

SETTING

Infectious disease center in Dar es Salaam, Tanzania.

METHODS

Participants included HIV-positive (n = 38) and HIV-negative (n = 38) adults aged 20 to 30 years who had clinically normal hearing, defined as type A tympanograms, air conduction thresholds ≤25 dB HL bilaterally from 0.5 to 8 kHz, and distortion product otoacoustic emissions (DPOAEs) >6 dB above the noise floor bilaterally from 1.5 to 8 kHz. Participants were tested multiple times over 6-month intervals (average, 2.7 sessions/participant) for a total of 208 observations. Primary outcome measures included tympanograms, air conduction audiograms, DPOAEs, and click-evoked auditory brainstem responses.

RESULTS

HIV groups did not significantly differ in age, static immittance, or air conduction thresholds. HIV-positive status was independently associated with approximately 3.7-dB lower DPOAE amplitudes from 2 to 8 kHz (95% CI, 1.01-6.82) in both ears and 0.04-µV lower (95% CI, 0.003-0.076) auditory brainstem response wave I amplitudes in the right ear.

CONCLUSION

Young adults living with HIV have slightly but reliably smaller DPOAEs and auditory brainstem response wave I amplitudes than matched HIV-negative controls. The magnitude of these differences is small, but these results support measuring peripheral auditory function in HIV-positive individuals as they age.

Towards a needs-based design of the physical rehabilitation workforce in South Africa: trend analysis [1990-2017] and a 5-year forecasting for the most impactful health conditions based on global burden of disease estimates

BACKGROUND

Rehabilitation can improve function in many people with chronic health conditions. It is important to consider priority conditions requiring rehabilitation, so it can be realistically positioned and costed in national health financing systems like South Africa (SA)'s proposed National Health Insurance (NHI). This paper describes temporal trends of top-ranked conditions on years lived with disability (YLDs) rates in SA, for which physical rehabilitation can ameliorate associated disability.

METHODS

This study is a systematic synthesis of publicly available Global Burden of Disease (GBD) 2017 estimates. The top 11 conditions contributing most to YLDs and for which evidence-based rehabilitation interventions exist were identified. Age-standardized rates per 100,000 and YLDs counts were extracted from 1990 to 2017. Significance of changes in temporal trends was determined using Mann-Kendall trend tests. Best-fit rates of yearly changes were calculated per condition, using GBD estimates (2012-2017), and extrapolated (by imposing the best-fit regression line onto results for each subsequent predicted year) as forecasts (2018-2022).

RESULTS

Trends for YLDs counts per condition year (1990-2017) and forecasted values (2018-2022) showed an overall steady increase for all conditions, except HIV and respiratory conditions. YLDs counts almost doubled from 1990 to 2017, with a 17% predicted increase from 2017 to 2022. The proportionate contribution to YLDs counts reduced over time for all conditions, except HIV. Although age-standardized YLDs rates appear relatively stable over the analyzed periods for all conditions (except HIV, respiratory conditions and type 2 diabetes), trend changes in YLDs rates over 28 years were significant for all conditions, except neonatal (p = 0.855), hearing loss (p = 0.100) and musculoskeletal conditions (p = 0.300). Significant trend decreases were apparent for 4/9 conditions, implying that another 5/9 conditions showed trend increases over 28 years. Predicted all-age prevalence in 2022 suggests relatively large increases for cardiovascular disease and heart failure, and burns, while relative decreases are predicted for fractures and dislocations, stroke, and musculoskeletal conditions.

CONCLUSION

Rehabilitation needs in SA are potentially massive and unmet, highlighting the need for innovative and context-specific rehabilitation that considers current local needs and projected changes. These findings should be considered when designing the NHI and other schemes in SA to ensure human and financial resources are deployed efficiently.

Audiological assessment of children with HIV/AIDS: a meta-analysis

OBJECTIVE

To analyze the results of the audiological evaluation of children with HIV and AIDS.

DATA COLLECTION

Systematic review carried out in May 2019 in the Web of Science, PubMed, SciELO, and Scopus databases. Case reports and original articles were included, with no limitationsregarding country or year of publication.

DATA SYNTHESIS

278 articles were identified; 26 were included, in which HIV/AIDS was shown to be a risk factor for hearing loss (OR=5.364; p=0.00). The studies used different audiological exams, with varying methodologies. There was no difference regarding the type of hearing loss (p=0.119).

CONCLUSION

Longitudinal studies using the same type of examination at all stages are suggested, to allow better monitoring of the effects of HIV on the child's hearing,and studies that provide more methodological details. The knowledge of the influence of HIV on the child's auditory system may lead to the promotion of measures that minimize the prevalence of hearing loss, allow an early diagnosis and timely rehabilitation, so as not to compromise child development.

Nature and extent of hearing loss in HIV-infected children: A scoping review

INTRODUCTION

Antiretroviral therapy (ART) has had a major impact on life expectancy from HIV as many people now live with it as a chronic disease. Chronic HIV has been associated with a range of comorbid disabilities and health conditions, one of which is hearing loss. Undiagnosed and untreated hearing loss, particularly in children, has been linked to poorer spoken language skills, with subsequent effects on academic performance.

METHODS

This systematic scoping review aimed to summarize the available peer-reviewed literature on hearing loss in HIV-infected children, specifically to describe its extent and nature. The review followed the framework proposed by Arksey and O'Malley. Key search terms included hearing loss (and synonyms), child (and synonyms), and HIV. Electronic databases (EBSCOhost Research Platform, PubMed, Web of Science and Scopus databases) were searched for any relevant articles published from January 1, 2000 to June 30, 2019. Reference lists of included articles were pearled for additional relevant articles not already identified. Each stage of the selection process was conducted independently by two authors. The results were then collated by a third author who also resolved any discrepancies. Extracted data included sample descriptors, audiologic tests, hearing loss prevalence, hearing loss descripts, and factors associated with hearing loss.

RESULTS

Seventeen articles were included; 10 from Africa, four from South America, two from North America and the remaining article from Asia. Although most of the articles reported on pure tone audiometry, the samples as well as the cut-off criteria for normal hearing were heterogenous. Prevalence of hearing loss varied across articles (from 6% to 84%). Conductive hearing loss occurred more frequently than sensorineural or mixed hearing loss. ART use and ear infection were reported as significant in three of five articles that reported on significant associates of HIV-related hearing loss.

CONCLUSION

There was a modest volume of research from a limited number of countries. Heterogeneity in sampling and audiometric methods precluded a clear understanding of potential associations between chronic HIV-related hearing loss and contributing factors.

Burden of disease: A scoping review of HIV/AIDS and TB in occupational noise-induced hearing loss

BACKGROUND

Occupational noise-induced hearing loss (ONIHL) does not occur in isolation from other influencing factors such as health conditions and illnesses like human immunodeficiency virus and acquired immunodeficiency syndrome (HIV and AIDS), as well as tuberculosis (TB). How the burden of disease influences the occurrence and/or management of ONIHL becomes a key if the goal of hearing conservation programmes (HCPs) is to be achieved within these contexts.

OBJECTIVES

The purpose of this scoping review was to conduct an investigation on how the burden of disease's influence on ONIHL is reported in literature, with a specific focus on the most prevalent diseases in South African mines - HIV and AIDS and TB.

METHOD

A scoping review was conducted using the Arksey and O'Malley's framework. A search was conducted in five electronic bibliographic databases and the grey literature.

RESULTS

The search procured 10 publications, with two specific to ONIHL within the South African context. In addition to the two publications specific to TB and ONIHL, findings revealed a serious gap in the evidence around the scoping review question globally. This obvious lack of investigations into the influence of these two conditions in the South African mining context raises serious implications about the responsiveness, and proactive nature of HCPs within this population.

CONCLUSION

Considering the burden of diseases on otology and audiology is critical as certain diseases cause hearing impairment either as a primary effect, as a secondary/opportunistic effect or as a side effect of treatment options for that disease. An employee suffering from any such disease with concomitant exposure to hazardous noise levels presents an even bigger challenge to HCPs if such is not taken into consideration in the conception, implementation and monitoring of HCPs.

Children with HIV: A scoping review of auditory processing skills

Introduction

Auditory processing disorders can negatively affect academic performance in children. They can result from a number of aetiologies, including the human immunodeficiency virus (HIV). Although studies in paediatrics are limited, research suggests that HIV-infected children display poorer auditory processing skills than uninfected children.

Methods

The aims of this study were to scan the peer-reviewed literature on auditory processing skills in HIV-infected children, to describe how auditory processing was tested, how auditory processing skills were reported, and to identify gaps in current evidence. This systematic scoping review was conducted using a modified version of Arksey and O’Malley’s framework. Key words comprised ‘HIV’, ‘auditory processing’, ‘hearing’ and ‘child’. Electronic databases were searched for relevant articles published from 1 January 2000 to 30 April 2018, and reference lists of included studies were pearled. Two researchers reviewed the articles and extracted data on sample descriptors, auditory processing testing procedures, and auditory processing skills. A third author collated the results and resolved discrepancies. The American Speech-Language-Hearing Association description of auditory processing skills framed the analysis.

Results

Five articles were included in this review (three from Brazil, one each from Mexico and Tanzania). Samples, and methods of testing were heterogeneous. Three studies reported on localization abilities, while gap detection thresholds, performance on dichotic tasks and speech discrimination scores were reported in one article each. No one study tested all areas of auditory processing skills and there was limited information about the auditory processing skills required for learning.

Conclusion

This review highlighted the current sparse evidence-base for auditory processing in HIV-infected children. It identified the need to standardise testing procedures, measures of auditory processing skills, and sample selection.

Otosyphilis: Resurgence of an Old Disease

OBJECTIVES

To describe the clinical characteristics of patients presenting with a new diagnosis of otosyphilis over the past 10 years in a large, urban, safety-net hospital affiliated with a large county sexually transmitted disease clinic.

METHODS

Retrospective case series. A chart review was performed of all patients who presented to an adult otolaryngology clinic with a new diagnosis of syphilis and hearing loss from January 2008 to December 2017.

RESULTS

Twelve patients met the criteria for "suspected" or "likely" otosyphilis based on Centers for Disease Control and Prevention definitions. The average age was 48 years (range 19-59). All were male. Nine (75%) were men who have sex with men. Eight (67%) were positive for human immunodeficiency virus. One (8%) presented with primary, nine (75%) with secondary, and two (17%) with early latent syphilis. Seven (58%) presented with bilateral audiogram-confirmed hearing loss, two (17%) with unilateral hearing loss, and three (25%) with suspected hearing loss based on fluctuating symptoms. Nine (75%) presented with tinnitus and two (17%) with vertigo. The median duration of otologic symptoms prior to presentation was 2 weeks (range: 0-16 weeks). All presented within the last 2 years surveyed.

CONCLUSION

We have seen an increase in the number of otosyphilis cases in our clinic. We suspect otosyphilis may be underdiagnosed and emphasize the importance of screening for syphilis in patients with new audiologic symptoms of vertigo, tinnitus, or hearing loss.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:1680-1684, 2019.

Prevalence of hearing loss at primary health care clinics in South Africa

BACKGROUND

Hearing loss prevalence data in South Africa is scarce, especially within primary health care settings.

OBJECTIVES

To determine; (i) the prevalence of hearing disorders in patients ≥3 years of age attending two primary health care clinics, and (ii) the nature and characteristics of hearing disorders at these primary health care clinics.

METHOD

A cross-sectional design was used at two primary health care clinics. Non-probability purposive sampling was used to screen participants at clinics for hearing loss with pure tone audiometry. A total of 1236 participants were screened (mean age 37.8 ±17.9 years). Diagnostic testing was available for confirmation of hearing loss on participants who failed the screening.

RESULTS

Hearing loss prevalence was 17.5% across both clinics. Most hearing losses were bilateral (70.0%) and were of a sensorineural nature (84.2%).

CONCLUSION

Hearing loss prevalence was comparable at both primary health care clinics. Participants 40 years and older were at significantly higher risk for hearing loss. The current study is the first attempt to establish hearing loss prevalence for primary health care clinics in South Africa.

Emerging and re-emerging infectious disease in otorhinolaryngology

SUMMARY

Emerging and re-emerging infectious disease in otorhinolaryngology (ENT) are an area of growing epidemiological and clinical interest. The aim of this section is to comprehensively report on the epidemiology of key infectious disease in otorhinolaryngology, reporting on their burden at the national and international level, expanding of the need of promoting and implementing preventive interventions, and the rationale of applying evidence-based, effective and cost- effective diagnostic, curative and preventive approaches. In particular, we focus on i) ENT viral infections (HIV, Epstein-Barr virus, Human Papilloma virus), retrieving the available evidence on their oncogenic potential; ii) typical and atypical mycobacteria infections; iii) non-specific granulomatous lymphadenopathy; iv) emerging paediatric ENT infectious diseases and the prevention of their complications; v) the growing burden of antimicrobial resistance in ENT and the strategies for its control in different clinical settings. We conclude by outlining knowledge gaps and action needed in ENT infectious diseases research and clinical practice and we make references to economic analysis in the field of ENT infectious diseases prevention and care.

Effect of antioxidant supplementation on the auditory threshold in sensorineural hearing loss: a meta-analysis

INTRODUCTION

Hearing loss is conceptualized as any impairment of the ability to hear and/or detect speech or environment sounds, regardless of cause, type, or degree. It may occur at different stages of life; during pregnancy or childbirth, in childhood, adulthood or old age. It should be noted that aging is the most common cause of sensorineural hearing loss followed by noise-induced hearing loss, and both are closely related to the formation of reactive oxygen species. Dietary antioxidant supplementation has been employed as a therapeutic strategy to prevent and/or delay the risks of major human diseases.

OBJECTIVE

To assess randomized clinical trials to determine the effect of antioxidant supplementation on the auditory thresholds in patients of different age groups with sensorineural hearing loss.

METHODS

This systematic review consisted of a search in the following databases: MEDLINE, CENTRAL, ScienceDirect, Scopus, Web of Science, LILACS, SciELO and ClinicalTrials.gov. Additionally, the gray literature was also searched. The search strategy included terms related to the intervention (antioxidant supplementation), primary outcome (sensorineural hearing loss), as well as terms related to randomized clinical trials to improve search sensitivity.

RESULTS

Based on 977 potentially relevant records identified through the search in the databases, ten full-text publications were retrieved for further evaluation. The increase in threshold at the 4kHz frequency was statistically higher in the control group (1.89 [1.01-2.78], p<0.0001) when compared to the NAC group and the ginseng group, whereas at 6kHz, the threshold increase was higher in the control group (1.42 [-1.14-3.97], p=0.28), but no statistically significant differences were found between groups.

CONCLUSION

Ginseng was the antioxidant agent that showed the best effect in preventing auditory threshold worsening at the frequency of 4kHz, but not at 6kHz in patients with sensorineural hearing loss caused by exposure to high sound pressure levels. There was no improvement in the thresholds with vitamin E supplementation.

Hearing Loss in HIV-Infected Children in Lilongwe, Malawi

INTRODUCTION

With improved access to antiretroviral therapy (ART), HIV infection is becoming a chronic illness. Preliminary data suggest that HIV-infected children have a higher risk of disabilities, including hearing impairment, although data are sparse. This study aimed to estimate the prevalence and types of hearing loss in HIV-infected children in Lilongwe, Malawi.

METHODS

This was a cross-sectional survey of 380 HIV-infected children aged 4-14 years attending ART clinic in Lilongwe between December 2013-March 2014. Data was collected through pediatric quality of life and sociodemographic questionnaires, electronic medical record review, and detailed audiologic testing. Hearing loss was defined as >20 decibels hearing level (dBHL) in either ear. Predictors of hearing loss were explored by regression analysis generating age- and sex-adjusted odds ratios. Children with significant hearing loss were fitted with hearing aids.

RESULTS

Of 380 patients, 24% had hearing loss: 82% conductive, 14% sensorineural, and 4% mixed. Twenty-one patients (23% of those with hearing loss) were referred for hearing aid fitting. There was a higher prevalence of hearing loss in children with history of frequent ear infections (OR 7.4, 4.2-13.0) and ear drainage (OR 6.4, 3.6-11.6). Hearing loss was linked to history of WHO Stage 3 (OR 2.4, 1.2-4.5) or Stage 4 (OR 6.4, 2.7-15.2) and history of malnutrition (OR 2.1, 1.3-3.5), but not to duration of ART or CD4. Only 40% of caregivers accurately perceived their child's hearing loss. Children with hearing impairment were less likely to attend school and had poorer emotional (p = 0.02) and school functioning (p = 0.04).

CONCLUSIONS

There is an urgent need for improved screening tools, identification and treatment of hearing problems in HIV-infected children, as hearing loss was common in this group and affected school functioning and quality of life. Clear strategies were identified for prevention and treatment, since most hearing loss was conductive in nature, likely due to frequent ear infections, and many children with hearing loss qualified for hearing aids. Screening strategies need to be developed and tested since caregivers were not reliable at identifying hearing loss, and often mis-identified children with normal hearing as having hearing loss. Children with frequent ear infections, ear drainage, TB, severe HIV disease, or low BMI should receive more frequent ear assessments and hearing evaluations.

Immune system of the inner ear as a novel therapeutic target for sensorineural hearing loss

Sensorineural hearing loss (SNHL) is a common clinical condition resulting from dysfunction in one or more parts in the auditory pathway between the inner ear and auditory cortex. Despite the prevalence of SNHL, little is known about its etiopathology, although several mechanisms have been postulated including ischemia, viral infection or reactivation, and microtrauma. Immune-mediated inner ear disease has been introduced and accepted as one SNHL pathophysiology; it responds to immunosuppressive therapy and is one of the few reversible forms of bilateral SNHL. The concept of immune-mediated inner ear disease is straightforward and comprehensible, but criteria for clinical diagnosis and the precise mechanism of hearing loss have not been determined. Moreover, the therapeutic mechanisms of corticosteroids are unclear, leading to several misconceptions by both clinicians and investigators concerning corticosteroid therapy. This review addresses our current understanding of the immune system in the inner ear and its involvement in the pathophysiology in SNHL. Treatment of SNHL, including immune-mediated inner ear disorder, will be discussed with a focus on the immune mechanism and immunocompetent cells as therapeutic targets. Finally, possible interventions modulating the immune system in the inner ear to repair the tissue organization and improve hearing in patients with SNHL will be discussed. Tissue macrophages in the inner ear appear to be a potential target for modulating the immune response in the inner ear in the pathophysiology of SNHL.

The global burden of disabling hearing impairment: a call to action

At any age, disabling hearing impairment has a profound impact on interpersonal communication, psychosocial well-being, quality of life and economic independence. According to the World Health Organization's estimates, the number of people with such impairment increased from 42 million in 1985 to about 360 million in 2011. This last figure includes 7.5 million children less than 5 years of age. In 1995, a "roadmap" for curtailing the burden posed by disabling hearing impairment was outlined in a resolution of the World Health Assembly. While the underlying principle of this roadmap remains valid and relevant, some updating is required to reflect the prevailing epidemiologic transition. We examine the traditional concept and grades of disabling hearing impairment - within the context of the International Classification of Functioning, Disability and Health - as well as the modifications to grading that have recently been proposed by a panel of international experts. The opportunity offered by the emerging global and high-level interest in promoting disability-inclusive post-2015 development goals and disability-free child survival is also discussed. Since the costs of rehabilitative services are so high as to be prohibitive in low- and middle-income countries, the critical role of primary prevention is emphasized. If the goals outlined in the World Health Assembly's 1995 resolution on the prevention of hearing impairment are to be reached by Member States, several effective country-level initiatives - including the development of public-private partnerships, strong leadership and measurable time-bound targets - will have to be implemented without further delay.