Search Results (78)

Background: Hearing loss (HL) affects more than 1.5 billion people worldwide and represents a major global health concern. Recent evidence suggests that alterations in gut microbial composition and antimicrobial resistance (AMR) may be linked to inflammatory and metabolic pathways that could influence auditory physiology. Objectives: This study aimed to explore the relationship between auditory function and the antimicrobial resistance in the gut microbiome of young adults. Methods: Fecal and auditory data were collected from young adults. Auditory function was assessed through pure-tone audiometry, and participants were classified according to the presence or absence of HL based on the American Speech-Language-Hearing Association (ASHA) criteria. Bacterial resistance was analyzed under aerobic and anaerobic conditions using disk diffusion and E-test methods to determine minimum inhibitory concentrations (MICs) for a panel of antibiotics. Gut microbiota composition was further characterized using quantitative polymerase chain reaction (qPCR) to quantify 15 key microbial taxa. Results: Overall, 40.9% of participants presented some degree of HL, with mild or slight HL being more frequent in women (53.3%) than in men (14.3%). Participants with HL exhibited significantly higher MICs for nalidixic acid, amoxicillin, and ciprofloxacin, as well as trends toward increased MIC variability for several other agents. Principal component analysis demonstrated distinct clustering of individuals without HL and greater dispersion among those with HL, suggesting higher interindividual variability in resistance profiles. These findings suggest potential associations between antimicrobial resistance and auditory function, possibly mediated through gut microbiome alterations. qPCR analyses demonstrated that Faecalibacterium prausnitzii abundance was significantly higher in individuals with HL and in those exhibiting greater resistance to amoxicillin. Conclusions: These findings provide preliminary evidence connecting the gut resistome with auditory function, supporting the emerging concept of a gut–ear–brain axis and underscoring the need for further research into microbiome-related mechanisms underlying HL. Full article

Background/Objectives: Children with hearing loss (HL) could experience significant fatigue which compromises their performance. The effort related to the combination of HL and visual impairment in children affected by Usher syndrome (USH) could compromise mental health, socio-emotional behavior and academic achievement. The aim of the present study was to analyse the listening effort in USH cases types 1 and 2 and its relation to age, molecular diagnosis, visual field, visual acuity, degree of HL, vestibular impairment and spatial orientation. Methods: This was a retrospective monocentric study. Twenty children with genetically confirmed USH (USH2 in 15/20–75% and USH1 in 5/20–25%), age range 3–17 years (mean 9.6 ± 4.7), underwent: the Vanderbilt fatigue scale questionnaire (VFS), audiological and vestibular assessment including the Oldenburg Matrix test in Italian and video head impulse test (VHIT), sound localization test and ophthalmologic examination. Results: We observed a more pronounced HL and deteriorated vestibular function in those with USH1. They also employed significantly more time and head movements to localize sounds compared to USH2 and had the worst visual field on eye examination. The VFS did not show significant differences between the two groups, with the exception of the physical fatigue reported by parents. Mean VFS was linearly related to age, the hearing threshold of the worse ear, data logging hours of hearing device, time and head movements of the localization test, VHIT asymmetry and balance problems referred by parents and the visual field. USH type 1 had no greater risk of fatigue than USH2. Profound hearing loss, data logging of hearing device < 8 h a day, difficult localization test, balance problems and low retinal sensitivity represented risk factors for listening effort measured with VFS. Conclusions: Listening effort in difficult environments such as school rooms in USH patients is not only associated to hearing function but also to the spatial awareness determined in part by vestibular and visual function. Teachers should be informed and made aware of multiple comorbidities in order to facilitate learning. Full article

This study aims to investigate the genotype characteristics of newborns with biallelic GJB2 mutations and their correlation with hearing phenotypes, providing a basis for clinical genetic counseling and hearing management. A retrospective study was conducted on 652 newborns with biallelic GJB2 mutations detected at the Newborn Diseases Screening Center of Shenzhen Maternal and Child Health Care Hospital from January 2022 to December 2024. The differences in mutation types, hearing screening, and diagnostic results were analyzed and compared between the homozygous and compound heterozygous mutation groups to assess their correlation with hearing phenotypes. Genotype analysis identified 543 cases of homozygous mutations, mainly the c.109G>A/c.109G>A genotype (98.90%). Compound heterozygous mutations were identified in 109 cases, with the majority being c.109G>A/c.235delC (76.15%). Following two-stage hearing screening, 227 (34.82%) of the 652 cases were referred, with bilateral failure accounting for the majority (81.94%) of these cases. The referral rates showed no significant difference between the homozygous (35.54%) and compound heterozygous (31.19%) groups (p > 0.05). The overall hearing loss detection rate was 6.90% (45/652); among these, eight infants who had initially passed the newborn hearing screening were later found to have hearing loss between 2.5 and 6 months of age. Among the 45 confirmed deaf children, hearing loss was mainly mild to moderate (87.50%), and profound deafness was only seen in the homozygous mutation group (10.29%, 7/68 ears). Most newborns with biallelic GJB2 mutations passed the two-stage hearing screening, and associated hearing loss was typically mild to moderate. Long-term auditory monitoring remains essential for all genetically confirmed infants to monitor late-onset progression. Full article

Background and Objectives: Labyrinthitis is an inflammatory inner ear disorder often resulting in acute vertigo and hearing loss. While typically self-limiting, some cases lead to persistent deficits. This study examined incidence trends of acute labyrinthitis before and after 2020 and compared hearing outcomes between these periods. Materials and Methods: This retrospective cohort study included 126 patients diagnosed with acute labyrinthitis at a tertiary medical center between January 2014 and May 2024. Patients were divided into pre-2020 (2014–2019) and post-2020 (2020–2024) cohorts. Poisson regression analyzed incidence trends, while audiometric outcomes were compared in 79 patients with complete 3-month follow-up data. Hearing recovery was assessed using pure-tone averages (PTA) across 500–4000 Hz, and predictors of persistent impairment were identified through multivariable logistic regression. Results: The cohort had a mean age of 47.8 years with female predominance (63.5%). Annual case counts increased significantly post-2020 (19.8 vs. 6.5 cases/year; CRR 3.05, 95% CI 2.07–4.57, p < 0.001). Substantial hearing improvement occurred across all frequencies (median AC improvement 13.8 dB). Hearing recovery was comparable between periods, with similar PTA improvements (−16.7 vs. −15.3 dB, p = 0.73) and equivalent distributions across World Health Organization (WHO) hearing categories (p = 0.64). Baseline hearing level was the strongest predictor of persistent impairment (OR 1.56 per 5 dB increase, 95% CI 1.25–1.95, p < 0.001), while age, sex, and diagnostic period showed no significant association. Among post-2020 patients, only 12.6% had confirmed coronavirus disease 19 (COVID-19), and no reliable association with hearing outcomes could be established due to substantial missing data. Conclusions: A significant increase in hospital-diagnosed labyrinthitis cases occurred following 2020, yet hearing outcomes at 3-month follow-up remained consistent with the pre-pandemic period. Baseline hearing level was the primary determinant of recovery, unaffected by demographic factors or diagnostic period. These findings suggest that while pandemic-related factors may have influenced case frequency, they did not alter auditory prognosis or recovery patterns. Full article

Objectives: The association between tinnitus and obstructive sleep apnea (OSA) has received attention; however, the mechanisms linking both conditions with diverse outcomes are still unclear. This study aimed to evaluate the association between OSA risk and tinnitus, including the OSA-related characteristics affecting tinnitus. Methods: We included participants aged 40–65 years with auditory examinations and STOP-BANG questionnaire between 2019 and 2021 from the Korean National Health and Nutrition Examination Survey data. Possible causative factors for tinnitus were identified using logistic regression analysis. Participants in the low- and high-risk groups for OSA were 1:1 matched using propensity score matching to compare the possible causative factors. Results: The high-risk group exhibited a higher incidence of tinnitus, persistence, and severity. However, when the causative factors of tinnitus were matched, no significant differences were observed. The most likely contributing factors were high-frequency hearing level in the worse ear for the experience and persistence of tinnitus and smoking for the severity of tinnitus. The high-risk group experienced tinnitus more often than the low-risk group, with no differences between the groups when tinnitus-affective factors were controlled. Conclusions: These findings suggest that tinnitus is unaffected by OSA itself but by the hearing loss that accompanies OSA. Full article

Purpose: Decentralized hearing care models facilitated by community health workers (CHWs) can improve access to care in low-income settings. Preset hearing aids, which offer user-selectable pre-developed amplification programs, may support such models, but little is known about their real-world use and alignment with clinical recommendations. Method: This longitudinal study formed part of a feasibility project implementing the World Health Organization’s (WHO’s) hearing aid service delivery approach in three low-income South African communities. Adults (≥18 years) with confirmed moderate-to-severe bilateral hearing loss were fitted with preset hearing aids by trained CHWs. Devices offered four preset amplification programs. Participant-driven selections were recorded at four distinct time points: fitting and follow-ups at 2 weeks, 2 months, and 6 months post-fitting. Results: In total, 36 participants (mean age = 76 years, SD = 8.9, range 50–96) were fitted with devices. Although over half (right: 52.8%, left: 58.3%) presented with high-frequency loss, only 34% initially selected the corresponding program. Most participants (80.6%, n = 29) changed their selections at least once over the six months. Significant associations between hearing loss configuration and selection occurred at some time points only in the left ear, but agreement with clinically recommended programs declined from 42% at baseline to 28% at six months. Conclusions: CHW-facilitated hearing aid delivery supports user autonomy in low-resource settings. However, frequent changes and divergence from clinically recommended programs suggest reliance on user-driven trial-and-error adjustments rather than audiometric fit, which may limit long-term benefit. Ongoing, person-centred guidance is needed for the effective use of preset hearing aids. Full article

Hearing loss is a major health burden, often caused by ototoxic drugs such as cisplatin and gentamicin. Effective therapy is limited by the poor penetrability of drugs into inner ear compartments. This study aimed to develop and test magnetic cationic liposomes as nanocarriers for targeted corticosteroid delivery to auditory hair cells. Carboxymethyl chitosan–coated liposomes were prepared by the lipid film hydration method, incorporating magnetic nanoparticles and dexamethasone phosphate in their aqueous core. The optimal liposomal formulation, in terms of size, zeta potential, and drug leakage over time, was selected and tested in an in vitro model of drug-induced ototoxicity. HEI-OC1 cells exposed to cisplatin or gentamicin were co-treated with the liposomal formulations, and viability, mitochondrial membrane potential, and β-galactosidase activity were assessed. The results demonstrated that magnetic, polymer-coated liposomes protected against cytotoxicity by preserving mitochondrial function and significantly reducing senescence. These findings provide a proof of concept for magnetically responsive liposomal systems as potential therapeutic platforms for preventing or treating drug-associated hearing loss. Full article

Hearing loss (HL) causes numerous challenges for individuals. N,N-diethyl-meta-toluamide (DEET) is a common ingredient in insect repellants and some sunscreens. M-(diethylcarbamoyl) benzoic acid (DCBA) is a DEET metabolite measured in the urine of National Health and Nutrition Examination Survey participants. This study examines potential associations between HL and urinary DCBA in U.S. adults. Speech-frequency hearing loss (SFHL) was defined as an average hearing threshold above 25 dB across four frequencies (0.5, 1, 2, and 4 kHz). In comparison, high-frequency hearing loss (HFHL) was based on the average threshold above 25 dB at three higher frequencies (3, 4, and 6 kHz) in the better hearing ear. Hearing loss severity was categorized as normal (≤25 dB), mild (26–40 dB), and moderate or worse (≥41 dB). Higher DCBA exposure was significantly associated with increased odds of high-frequency hearing loss (HFHL). Participants in the highest exposure quartile had greater odds of HFHL (aOR = 2.34; 95% CI: 1.14–4.81), with a dose–response trend (p < 0.05) confirmed in sensitivity analyses controlling for chronic conditions and inflammation. Multinomial models further showed elevated odds of both slight/mild (aOR = 2.15; 95% CI: 1.05–4.42) and moderate/worse HFHL (aOR = 2.84; 95% CI: 1.10–7.37), supporting the robustness of the association. To our knowledge, this is the first report of HL being associated with a DEET metabolite in a nationally representative cross-sectional sample. Full article

Background: Mitochondrial substrate switching plays an important role in aging. The substrate metabolic rate is closely related to mitochondrial activity, as mitochondria are the primary site for substrate oxidation and ATP production. Different substrates (glucose, amino acids, and fatty acids) enter the mitochondria through distinct pathways and are metabolized at different rates, depending on the energy demand and cellular conditions. However, it remains unclear how the mitochondrial metabolic rate of these substrates affects auditory cellular function. This study aimed to characterize the substrate-dependent mitochondrial respiratory responses of cochlear cells under varying energy supply conditions and metabolic stress, focusing on glucose, amino acids, and fatty acids as representative energy sources. Methods: The oxygen consumption rate (OCR) was measured after substrate addition using an Agilent Seahorse XF24 Flux Analyzer In-House Ear Institute-Organ of Corti 1 (HEI-OC1) cells, and the maximum OCR (MOCR) was determined as part of the mitochondrial stress test. Statistical analyses were performed using analysis of variance (ANOVA). Results: The OCR increased significantly after glutamine (L-Gln) or palmitate addition. The MOCR after L-Gln addition was significantly higher than that after glutamic acid, glycine, and phenylalanine addition. The MOCR after pyruvate addition was significantly higher than that after glucose addition. However, there was no significant increase in the MOCR after fatty acid addition. Conclusions: Glucose is essential for basal metabolism but cannot rapidly meet sudden energy demands. Pyruvate and L-Gln serve as effective substrates for short-term, high-intensity energy demands. Fatty acids increase OCR through mitochondrial uncoupling effects, though their role may be limited in inner ear cells. These findings provide a foundation for exploring metabolic interventions to support cochlear function and hearing health. Full article

Noise-induced hearing loss (NIHL) is a significant occupational health issue, characterized by permanent damage to the cochlea due to prolonged exposure to high-intensity noise. Circulating microRNAs (c-miRNAs) have emerged as promising non-invasive indicators of inner ear pathology and potential modulators of cellular stress responses. Nevertheless, their specific roles in NIHL remain inadequately characterized. This study evaluated miRNA expression in the peripheral blood of individuals with bilateral NIHL (n = 12) and matched healthy controls (n = 6) using GeneChip^® miRNA 4.0 arrays. The Transcriptome Analysis Console software was used for differential expression analysis, and bioinformatic predictions of gene targets and pathway enrichment were performed using TargetScan (version 8.0) and the Enrichr tool. Among the 72 differentially expressed miRNAs (FDR < 0.05), hsa-miR-486-2, hsa-miR-664b-3p, hsa-miR-4485, hsa-miR-501, and hsa-miR-663b were notably upregulated, while hsa-miR-6723, hsa-miR-194-2, hsa-miR-668-5p, hsa-miR-4722-3p, and hsa-miR-4716 showed significant downregulation. Enrichment analyses indicated involvement in apoptosis regulation, mitochondrial stability, and cell cycle control. Principal component analysis (PCA) and clustering methods revealed clear molecular distinctions between the patient and control groups. The observed alterations in c-miRNA profiles highlight their relevance to NIHL-related cellular stress and degeneration. These findings support their utility as candidate biomarkers for diagnosis and prognosis, warranting further validation in functional and longitudinal studies. Full article

Firefighters experience high noise levels from various sources, such as sirens, alarms, pumps, and emergency vehicles. Unlike industrial workers who experience continuous noise exposure, firefighters are subject to intermittent high-intensity noise, increasing their risk of noise-induced hearing loss (NIHL). Despite global concerns regarding firefighters’ auditory health, research on Korean firefighters remains limited. This study aimed to assess personal noise exposure among Korean firefighters across three primary job roles—fire suppression, rescue, and emergency medical services (EMS)—and to predict worst-case noise exposure scenarios. This study included 115 firefighters from three fire stations (one urban, two suburban). We measured personal noise exposure using dosimeters attached near the ear following the Korean Ministry of Employment and Labor (MOEL) and International Organization for Standardization (ISO) criteria. Measurements included threshold levels of 80 dBA, exchange rates of 5 dB (MOEL) and 3 dB (ISO), and a peak noise criterion of 140 dBC. We categorized firefighters’ activities into routine tasks (shift handovers, equipment checks, training) and emergency responses (fire suppression, rescues, EMS calls). We performed statistical analyses to compare noise levels across job roles, vehicle types, and specific tasks. The worst-case exposure scenarios were estimated using 10th percentile recorded noise levels. The average 8 h time-weighted noise exposure levels varied significantly by job role. Rescue personnel exhibited the highest mean noise exposure (MOEL: 71.4 dBA, ISO: 81.2 dBA; p < 0.05), whereas fire suppression (MOEL: 66.5 dBA, ISO: 74.2 dBA) and EMS personnel (MOEL: 68.6 dBA, ISO: 73.0 dBA) showed no significant difference. Peak noise levels exceeding 140 dBC were most frequently observed in rescue operations (33.3%), followed by fire suppression (30.2%) and EMS (27.2%). Among vehicles, noise exposure was the highest for rescue truck occupants. Additionally, EMS personnel inside ambulances had significantly higher noise levels than drivers (p < 0.05). Certain tasks, including shift handovers, equipment checks, and firefighter training, recorded noise levels exceeding 100 dBA. Worst-case scenario predictions indicated that some work conditions could lead to 8 h average exposures surpassing MOEL (91.4 dBA) and ISO (98.7 dBA) limits. In this study, Korean firefighters exhibited relatively low average noise levels. However, when analyzing specific tasks, exposure was sufficiently high enough to cause hearing loss. Despite NIHL risks, firefighters rarely used hearing protection, particularly during routine tasks. This emphasizes the urgent need for hearing conservation programs, including mandatory hearing protection during high-noise activities, noise exposure education, and the adoption of communication-friendly protective devices. Future research should explore long-term auditory health outcomes and assess the effectiveness of noise control measures. Full article

Background and objective: Currently, there is no universal newborn hearing (UNHS) screening in the Democratic Republic of Congo (DRC), partly due to financial and organizational reasons. The aim of this study was to adapt the LittlEARS^® Auditory Questionnaire (LEAQ) into the Kiswahili and Lingala languages for use as a screening tool for auditory development in children less than two years of age, as objective hearing screening cannot be performed nationwide. Methods: For this purpose, norm data were collected from n = 723 infants (Lingala) and n = 648 infants (Kiswahili) aged between 0 and 24 months in a random selection of four out of seven health zones with pediatric services in the DRC. A non-linear regression model was derived for total scores by age. Pearson correlations were performed to determine whether there were differences between total scores of the questionnaire by region (urban/rural areas). A Mann–Whitney U-test was calculated to determine if there were differences depending on who completed the questionnaire (mother/other caregiver). In addition, a one-way ANOVA was used to determine whether there were differences in the total scores of the questionnaires according to the educational background of the person completing the questionnaire. Results: The Pearson correlation coefficient between total scores and age was 0.81 for Kiswahili and 0.77 for Lingala. There were no significant differences in total scores for all conditions tested (total scores by age, language, region, person who completed the questionnaire, educational background). Conclusions: The LEAQ can be used effectively in a large region such as the DRC, regardless of the region, respondent, and the educational background. Full article

Pesticide exposure poses a significant health risk, with emerging evidence suggesting its impact on auditory function. This study investigated the effects of pesticide exposure on hearing in young rural residents living near agricultural areas in Chile’s O’Higgins Region. We evaluated 51 participants (31 exposed, 20 unexposed) aged 18–35 years, using comprehensive audiological assessments including high-frequency audiometry, distortion product otoacoustic emissions (DPOAEs), and auditory brainstem responses (ABR). Participants were classified based on residential proximity to agricultural areas, with exposed individuals living around 400 m or less from monoculture fields. Results revealed significant differences in high-frequency hearing thresholds (14 and 16 kHz) in exposed individuals. The exposed group showed a higher number of absent DPOAEs and reduced ABR wave V amplitude in the right ear compared to the unexposed group. Additionally, the wave V/I ratio was significantly lower in exposed individuals. These findings suggest that pesticide exposure, even without direct occupational contact, may induce measurable changes in auditory function, particularly affecting high-frequency hearing and neural responses. These results emphasize the need for enhanced monitoring and protective measures for populations residing near agricultural areas where pesticides are extensively used. Full article

Diabetes mellitus (DM) is a common chronic health condition, affecting millions of people worldwide, and its incidence is projected to increase by almost 50% in the next two decades. The effects of DM on the auditory system have been reported. However, there is limited evidence on the association between DM and middle ear pathologies. This scoping review aimed to map the available evidence and identify research gaps regarding DM and middle ear pathologies in the adult population. Five electronic databases, namely Scopus, CINAHL, MEDLINE, PubMed, and Web of Science, were searched using a combination of specific key terms. This review followed the guidelines stipulated by the Joanna Briggs Institute (JBI) methodology for scoping reviews and reporting using PRISMA Extension for Scoping Reviews (PRISMA-ScR): checklist and explanation. A thematic narrative analysis was used to synthesize key findings. Of the 1809 articles, only 2 articles met the inclusion criteria. Neither of these studies focused exclusively on middle ear pathologies in DM, but they did report incidental findings related to middle ear function. Available evidence suggests that middle ear pathologies may occur in individuals with DM, with a reported prevalence ranging from 3.1% to 19.6%. Otitis media with effusion and conductive hearing loss were common middle ear pathologies identified. Additionally, recent studies have provided new evidence suggesting ossicular joint changes in individuals with DM and a causal link between DM and acute suppurative otitis media. However, age-related hearing loss (presbycusis) and sensorineural hearing loss (SNHL) were more commonly associated with DM, with studies reporting a high prevalence of SNHL in younger to middle-aged adults with diabetes. This review highlights a significant research gap in the literature, as no studies directly investigated the relationship between DM and middle ear function as a primary focus. Further research is required to investigate this potential association using methodologies explicitly designed for middle ear assessment. While some evidence suggests a possible association, the lack of age-stratified analyses, imaging data, and comprehensive diagnostic testing limits the ability to draw strong conclusions. Further research incorporating age-based analyses, radiological assessments, and microbiome studies is needed to fully understand the potential impact of DM on middle ear health. Full article

The misuse of personalized listening devices (PLDs) resulting in noise-induced hearing loss (NIHL) has become a public health concern, especially among youths, including medical students. The occupational use of PLDs that produce high-intensity sounds amplifies the danger of cochlear deterioration and high-frequency NIHL especially when used in noisy environments. This study aims to evaluate the incidence and trends of NIHL among medical students using PLDs. Background/Objectives: The purpose of this study is to assess the prevalence of high-frequency NIHL among PLD-using medical students. Methods: A semi-structured questionnaire covering details on PLD usage, exposure to noisy environments, and hearing difficulties was used to gather the data required. Conventional pure-tone audiometry with extended high-frequency audiometry was preceded by routine clinical evaluation using tuning fork tests and otoscopic examination for hearing loss assessment and to rule out middle-ear pathology. Hearing impairment was determined and categorized according to the Goodman and Clark classification system (250 Hz to 8000 kHz). SPSS version 21 was used in the analysis of the frequency data collected. Results: Out of 100 participants, using conventional PTA, 33% were found to have hearing loss, with 42.9% of males and 23.5% of females affected. Bilateral hearing loss was seen in 36.4% of the cases. Left-sided hearing loss was found to be more common (28%). The duration of usage of PLD had a significant correlation with hearing loss with a p-value < 0.0001. Hearing thresholds were significantly elevated at 16 kHz and 18 kHz in both the right and left ear. Conclusions: The high prevalence of PLD misuse among medical students is a major risk factor for NIHL. To help combat chronic hearing loss, students need to be educated about safe listening levels that can prevent further damage to the cochlea and auditory system. Full article