Major Cause Of Hearing Impairment Research Articles

Prevalence and clinico-bacteriological aspects of chronic suppurative otitis media at the Renaissance University Hospital in N'Djamena, Chad

BackgroundChronic suppurative otitis media is a major cause of hearing impairment and morbidity in poor socioeconomic developing countries.ObjectivesTo determine the prevalence of chronic suppurative otitis media in a tertiary care hospital and to analyze its clinico-bacteriological aspects.MethodsThis is a cross-sectional, descriptive and analytical study conducted at the ENT and Head and Neck Surgery Department in the Renaissance University Hospital in N'Djamena, Chad. All the patients that were diagnosed with chronic suppurative otitis media from 1 January 2017 to 31 December 2019 were included.ResultsThe hospital prevalence was 6.1%. The sex ratio (male/female) was 1.09. The median age of patients was 28 years with [1 to 74 years]. The median time from the onset of otorrhea to coming for medical consultation was 6 years with [4 months to 42 years]. The main symptom associated with otorrhea was hearing impairment which was in 55.6% of cases (n = 50). Perforations ≥ ¾ of the tympanic membrane surface were noted in 51.3% of cases (n = 60). The tympanic cavity floor was erythematous in 49.6% of cases (n = 58) and erythematous with a discharge in 42.7% of cases (n = 50). There was an association between the size of the perforation and the appearance of the tympanic mucosa (p = 0.003), and between the age of the disease and the side of the ear affected with chronic suppurative otitis media (p = 0.016). The culture positivity rate was 86.1% (n = 31) and with two other microbial cases. Staphylococcus aureus was isolated in 28.1% of cases (n = 9) followed by Pseudomonas aeruginosa which was 25% of the cases (n = 8).ConclusionChronic suppurative otitis media affects both children and adults. Delay in medical consultation to the ENT department is relatively high. Staphylococcus aureus and Pseudomonas aeruginosa are the most common causes.

CHARACTERISTICS AND FACTORS ASSOCIATED WITH HEARING LOSS (DEAFNESS) IN CHILDREN ATTENDING THE MEDICAL CITY HOSPITAL, BAGHDAD, IRAQ

Background: Hearing loss (HL) is one of the commonest and neglected childhood disabilities. According to the World Health Organization (WHO), most of childhood hearing impairment is preventable. Studies showed that 31% of hearing impairment cases are caused by prenatal and postnatal infections, 17% are birth-related causes, 4% are ototoxic medications and about 8% related to other causes such as maternal substance abuse. Objective: To review factors associated with HL in a sample of children attending the Medical City Hospital in the Pediatrics Outpatient Clinic and Auditory Clinic; including congenital, early, or late onset and to investigate risk factors associated with HL. Methods: A cross sectional study, included children <15 years with hearing loss attending the Medical City Hospital in the Pediatrics Outpatient Clinic and Auditory Clinic during the period from the 1st of July 2021 till the 30th of October 2021. Results: One hundred and one children with HL; 65.3% of them were males, 71.3% were preschoolers, 60.4% of them had family history of deafness, Severe deafness was found among 45.5% of children. Management was by Cochlear implantation for 60.4% of them and hearing aid for the rest. Causes of deafness were unknown in 39.6% of children, congenital among in 37.6%, acquired in 15.8% and mixed causes in 6.9%. Conclusion: Hearing impairment is severe deafness in most of the children included in this study. Family history, congenital infections and otitis media were the major causes of hearing impairment. Finally, cochlear implant was the management of choice in the majority of these children. Keywords: Hearing loss, cochlear implant, otitis media Citation: Qasim MF, AbdulKareem MN, Issa MA. characteristics and factors associated with hearing loss (deafness) in children attending the Medical City Hospital, Baghdad, Iraq. Iraqi JMS. 2022; 20(1): 68-76. doi: 10.22578/IJMS.20.1.9

The role of high-resolution computerized tomography as a diagnostic tool in the evaluation and planning of management of patients with chronic otitis media

Context: Chronic otitis media (COM), a major cause of hearing impairment and its associated morbidity and mortality can be avoided with proper diagnosis and planned management. High-resolution computerized tomography (HRCT) is accessible and possesses role in the detection of COM. Aims: This study aims to evaluate the role of HRCT as a diagnostic tool in the evaluation and planning of management of patients with COM. Settings and Design: Prospective observational study. Subjects and Methods: The study included 100 subjects presenting with COM planned for detailed otorhinolaryngological and otoscopic examination, pure tone audiomentry, non-contrast HRCT of bilateral temporal bones and were exposed to initial medical management of symptoms and surgical management. Statistical Analysis Used: Data were expressed as percentage and mean ± standard deviation Kolmogorov–Smirnov analysis was performed for checking linearity of the data. Fischer's exact test or Chi-square test was used to analyze the significance of the difference between frequency distribution of the data. Results: For soft tissue attenuation, HRCT was 100% sensitive and specific for the presence of soft tissue mass. HRCT found to be 100% accurate in predicting cholesteatoma presence and was found to be sensitive in the range of 83.3%–100% and specific in range 87.04%–100%. For bony erosion, HRCT was found to be fairly accurate. These comparisons were found to be highly significant with P

MiR-210 regulates the inflammation of otitis media with effusion by inhibiting the expression of hypoxia-inducible factor (HIF)-1a

Otitis media with effusion (OME) is the major cause of hearing impairment in children. miR-210 plays a critical role in inflammatory diseases, however, its role in OME is unknown. In this study, the miR-210 level in serum and middle ear effusion of is significantly down-regulated in serum, middle ear effusion from OME patients (100 cases) compared with healthy volunteers (50 cases). The expression of miR-210 is closely related to inflammatory factors and bone conduction disorder in patients with OME. In the in vitro study，the miR-210 level is significantly reduced in culture supernatant of lipopolysaccharide (LPS) treated human middle ear epithelial cells (HMEECs). miR-210 overexpression inhibited the LPS-induced in inflammatory cytokines production, cell viability reduction and cell apoptosis. Bioinformatics and dual-luciferase reporter assay showed that HIF-1a was a target gene of miR-210. The biological effects of miR-210 on cell viability, cell apoptosis and inflammation cytokines in LPS-induced HMEECs were reversed by HIF-1a overexpression. Furthermore, phosphorylation of NF-κB p65 was significantly decreased by miR-210 mediated HIF-1a in LPS-induced HMEECs. This study suggested that miR-210 may play a role in OME. Further studies are warranted to assess miR-210 as a potential target for the diagnosis and treatment of OME.

Molecular Mechanisms and Biological Functions of Autophagy for Genetics of Hearing Impairment.

The etiology of hearing impairment following cochlear damage can be caused by many factors, including congenital or acquired onset, ototoxic drugs, noise exposure, and aging. Regardless of the many different etiologies, a common pathologic change is auditory cell death. It may be difficult to explain hearing impairment only from the aspect of cell death including apoptosis, necrosis, or necroptosis because the level of hearing loss varies widely. Therefore, we focused on autophagy as an intracellular phenomenon functionally competing with cell death. Autophagy is a dynamic lysosomal degradation and recycling system in the eukaryotic cell, mandatory for controlling the balance between cell survival and cell death induced by cellular stress, and maintaining homeostasis of postmitotic cells, including hair cells (HCs) and spiral ganglion neurons (SGNs) in the inner ear. Autophagy is considered a candidate for the auditory cell fate decision factor, whereas autophagy deficiency could be one of major causes of hearing impairment. In this paper, we review the molecular mechanisms and biologic functions of autophagy in the auditory system and discuss the latest research concerning autophagy-related genes and sensorineural hearing loss to gain insight into the role of autophagic mechanisms in inner-ear disorders.

Genomics of Otitis Media (OM): Molecular Genetics Approaches to Characterize Disease Pathophysiology.

Otitis media (OM) is an infective and inflammatory disorder known to be a major cause of hearing impairment across all age groups. Both acute and chronic OM result in substantial healthcare utilization related to antibiotic prescription and surgical procedures necessary for its management. Although several studies provided evidence of genetics playing a significant role in the susceptibility to OM, we had limited knowledge about the genes associated with OM until recently. Here we have summarized the known genetic factors that confer susceptibility to various forms of OM in mice and in humans and their genetic load, along with associated cellular signaling pathways. Spotlighted in this review are fucosyltransferase (FUT) enzymes, which have been implicated in the pathogenesis of OM. A comprehensive understanding of the functions of OM-associated genes may provide potential opportunities for its diagnosis and treatment.

Assessment of Hearing Loss among Workers in a Power Plant in Thailand

Noise exposure in the working environment is a major cause of hearing impairment for workers; an audiogram hearing threshold level above 20 dB is considered irregular. In this study, audiometric data were analyzed with the objective of assessing hearing loss among power plant workers based on their age, noise exposure level, years of working, and work characteristics. A cross-sectional study was conducted to assess hearing level data for 672 workers reserved by the Health Care Unit of the power plant. The most recent audiometric data presented during 2013-2015 were used in the statistical analysis at 5 % level of significance. It was found that the most dominant frequency with reference to age and work experience is the test frequency at 4,000 Hz. The most prominent suffering significant hearing loss for both ears is the age group of 50-60 years, consistent with more than 35 years of working. The most significant exposure level is noise level at 81-84 dBA for the left ear only. The work characteristics were found to be the most significant factor affecting hearing loss in both ears. The t-test reveals no significant difference in hearing loss in both ears at all test frequencies. Hearing loss is found to occur at 4,000 and 6,000 Hz; therefore, there is a necessity to implement noise control measures specifically for each work group. Although there is an educational and training program in the power plant, all workers should still be educated continuously on how to use hearing protection equipment correctly to enhance awareness of the hazards of noise to hearing. Periodic audiometry should be performed to early detect noise-induced hearing loss specifically the notch occurring at 4,000 and 6,000 Hz, together with engineering control in order to reduce unwanted sound.

Effect of age and duration of driving on hearing status of Indian agricultural tractor drivers

Tractor noise is critical occupational hazard which is the major cause of hearing impairment among Indian agricultural farm workers. The study aimed to show the effect of age and driving exposure on hearing impairment of drivers. Ninety healthy male subjects of similar age, height, and weight were selected and divided into four groups, i.e. 21–30, 31–40, 41–50, and 51–60 years. The audiometric testing was conducted of both the ears at 10 different frequencies, i.e. 0.125, 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, and 8 kHz. The hearing threshold levels of office workers at audiometric test frequencies did not exceed 25 dB(A) to cause hearing handicap. However, it exceeded 25 dB(A) for tractor drivers and was higher for higher age group tractor drivers. Whereas, it did not exceeded 25 dB(A) at the audiometric test frequencies for the office workers except at 51–60 years of age group. Also, with the increase in age group and increase of driving experience, the mean hearing threshold levels of tractor drivers increase. It was concluded that the occupational hazards of tractor driving significantly increased the hearing threshold levels and the risk is even higher for the tractor drivers with ≥15 years of driving experience. Also, the mean hearing threshold levels for tractor drivers increase with increase in driving experience.

Fungal Suppurative Otitis Media (Histopathology) Among Patients in North India.

Chronic suppurative otitis media (CSOM) has a substantial worldwide prevalence and is a major cause of hearing impairment. In cases of CSOM unresponsive to local antibiotics, superimposed fungal infection should be suspected. The aim of the present study was to study the spectrum of cases with fungal otitis media. The study was conducted over a period of 12years (2006-2017). Fifteen cases of CSOM clinically not suspected to be of fungal etiology that underwent surgery with identification of fungal organisms on histopathology were included in the study. Age of the patients ranged from 12 to 75years (mean age: 37.1 ± 22.7years). Of 15 cases, 9 (60.0%) were males and 6 (40.0%) were females. It was a unilateral presentation in all. The complaints observed were ear discharge in all followed by itching (86.7%), pain (46.7%), decreased hearing (26.7%) and blocking sensation (13.3%). Histomorphologic typing of fungus was possible in 13/15 patients. Isolated aspergillus was identified in eight patients while mucor alone was seen in three patients. Mixed infection with Aspergillus + Candida and Aspergillus + Mucor was seen in one patient each. Categorization of fungus could not be done in rest of the two patients due to paucity of fungal profiles. Histopathological identification of fungal organisms in otomycosis provides a quick and fairly reliable diagnosis. Culture is considered the gold standard but it may not always be available or fruitful. Less turnaround time and accurate diagnosis facilitates prompt and optimal therapy in fungal otitis media thus preventing adverse outcomes.

Risk factors of sensorineural hearing loss in patients with unilateral safe chronic suppurative otitis media

PurposeChronic suppurative otitis media (CSOM) is the major cause of hearing impairment, especially conductive hearing loss. Few patients also had sensorineural component, the sensorineural hearing loss (SNHL) in CSOM is controversial, especially for safe mucosal type. This study aims to assess the relationship between the frequency of SNHL development in patients with safe mucosal CSOM and its relation to patient's age, sex, duration of disease, size of perforation and different audiological findings. Material and methodsThis is a prospective study conducted from June 2016 to June 2017 in a tertiary referral hospital. 200 patients with unilateral mucosal type of CSOM with normal contralateral ear were included in the study. The diseased ears were taken as study ears and normal ears as control ears in all patients. Detailed otologic history, clinical and audiometric findings were recorded and analyzed. Results were statistically compared in all patients for both study and control ears using different parameters. ResultsTwenty patients had an average bone conduction threshold of all frequencies above 25dB, which implies SNHL (10%). The incidence of SNHL was statistically significant at higher speech frequencies. The incidence increased with the presence of Diabetes Mellitus, smoking, duration of disease, presence of active discharge and the increase in size of perforation. However, it is not age dependent and there was no difference between males and females. ConclusionSafe mucosal CSOM can cause SNHL with multiple predisposing factors.

The Role of Mannose-Binding Lectin Serum Level in Tubotympanic Chronic Suppurative Otitis Media.

Background Chronic suppurative otitis media (CSOM) is a common public health problem worldwide and a major cause of hearing impairment especially in developing countries. The role of Mannose-Binding Lectin (MBL), a component of innate immunity, in CSOM has not been studied. The aim of the study was to examine whether MBL deficiency was more frequently present in cases group of tubotympanic CSOM patients rather than healthy subjects. Material and Methods This was an analytic observational study. Subjects were enrolled in the Otorhinolaryngology Clinic at Margono Soekarjo Hospital, Purwokerto, Indonesia. An independent t-test was used to compare the mean of MBL serum concentration between tubotympanic CSOM subjects and control. Results From 36 tubotympanic CSOM patients, there were 8 (22.22%) patients with MBL deficiency (MBL level < 100 ng/ml), while no deficiency was found in the control group. The mean of MBL level in cases group was 354.88 ng/ml, with the lowest level being 0.001 ng/ml and the highest level 690.24 ng/ml, while in the control group MBL level mean was 376.27 with the lowest level being 188.71 and the highest level 794.54 ng/ml. Conclusion There was no significant difference of MBL serum level between tubotympanic CSOM and control group. However, the presence of subjects with MBL deficiency in the tubotympanic CSOM group might be considered as playing a role in the tubotympanic CSOM.

Expression of tumor necrosis factor - α (TNF-α) and interleukin 1-β (IL1-β) in chronic tubotympanic suppurative otitis media

Chronic Suppurative Otitis Media (CSOM) is a common public health problem worldwide and a major cause of hearing impairment. It is also one of the neglected disease especially in developing countries. Cytokines are a group of glycoproteins that play a role in strengthening the immune and inflammatory reactions in various diseases, including inflammation of the middle ear. Some of the important inflammatory mediators found in middle ear fluids are Tumor Necrosis Factor-α (TNF-α) and Interleukin-1β (IL-1β). Cytokines are thought to play a role in the ongoing inflammatory regulation. The aim of this study was to compare the expression of TNF-α and IL-1β in tubotympanic CSOM and in healthy control group. The mean of TNF-α serum level in tubotympanic CSOM was 0,553±1,59 pg/ ml, and 0,587±2,13 pg/ ml in control group. There was no statistically different of TNF-α between two groups (P > 0,05). Mean of IL-1β serum level in the tubotympanic CSOM and control group were 0,633±0,92 and 0,302±0,48, respectively. Although IL-1β levels were higher in the patient group, the difference was not statistically significant (P > 0,05).

Novel compounds protect auditory hair cells against gentamycin-induced apoptosis by maintaining the expression level of H3K4me2

Aminoglycoside-induced hair cell (HC) loss is a major cause of hearing impairment, and the effective prevention of HC loss remains an unmet medical need. Epigenetic mechanisms have been reported to be involved in protecting cochlear cells against ototoxic drug injury, and in this study we developed new bioactive compounds that have similar chemical structures as the epigenetics-related lysine-specific demethylase 1 (LSD1) inhibitors. LSD1 inhibitors have been reported to protect cochlear cells by preventing demethylation of dimethylated histone H3K4 (H3K4me2). To determine whether these new compounds exert similar protective effects on HCs, we treated mouse cochlear explant cultures with the new compounds together with gentamycin. There was a severe loss of HCs in the organ of Corti after gentamycin exposure, while co-treatment with the new compounds significantly protected against gentamycin-induced HC loss. H3K4me2 levels in the nuclei of HCs decreased after exposure to gentamycin, but H3K4me2 levels were maintained in the presence of the new compounds. Apoptosis is also involved in the injury process, and the new compounds protected the inner ear HCs against apoptosis by reducing caspase-3 activation. Together, our findings demonstrate that our new compounds prevent gentamycin-induced HC loss by preventing the demethylation of H3K4me2 and by inhibiting apoptosis, and these results might provide the theoretical basis for novel drug development for hearing protection.

Mutations in OTOF, CLDN14 & SLC26A4 genes as major causes of hearing impairment in Dhadkai village, Jammu & Kashmir, India.

Background & objectives:A high incidence of hearing impairment is reported from the village of Dhadkai in the State of Jammu and Kashmir, India. Prevalence of endogamy in this community suggested a common genetic basis for the disorder. A genetic study was undertaken to ascertain the basis for the high incidence of hearing impairment in this region.Methods:In a two-step approach to identify the causative mutation/s, a whole-genome-based linkage analysis of an extended family of 45 members was carried out, which included 23 affected and 22 unaffected members. Mutational analysis for the candidate deafness genes helped reveal causative mutations in the family. In addition, seven deafness-causing genes, Cx26, SLC26A4, CLDN14, TMPRSS3, TMC1, TMIE and USH1C, were analyzed in smaller families with hearing impairment.Results:In the 45-member extended family, the critical chromosomal region mapped to 2p24-p22. The c.2122C>T (p.R708X) mutation in OTOF in 2p24-p22was identified as being the causal change. Linkage to 2p24-p22 locus was not observed in a particular branch of this extended family. Analysis of seven known deafness-causing genes in this branch revealed a mutation, c.254T>A (p.V85D), in CLDN14. Among seven small families unrelated to the 45-member extended family, hearing loss was attributable to p.R708X in OTOF in three families and to p.V85D in CLDN14 in one family; a new mutation c.1668T>A (p.Y556X) SLC26A4 was identified in two families and the causative change could not be identified in one family.Interpretation & conclusions:This study suggested considerable genetic heterogeneity in the causation of hearing loss in Dhadkai. Recessive mutations were observed in at least three genes causing hearing loss: OTOF (p.R708X), SLC26A4 (p.Y556X) and CLDN14 (p.V85D). Mutation p.R708X appeared to be the major cause of hearing impairment in Dhadkai.

Spectrum and Frequency of the GJB2 Gene Pathogenic Variants in a Large Cohort of Patients with Hearing Impairment Living in a Subarctic Region of Russia (the Sakha Republic).

Pathogenic variants in the GJB2 gene, encoding connexin 26, are known to be a major cause of hearing impairment (HI). More than 300 allelic variants have been identified in the GJB2 gene. Spectrum and allelic frequencies of the GJB2 gene vary significantly among different ethnic groups worldwide. Until now, the spectrum and frequency of the pathogenic variants in exon 1, exon 2 and the flanking intronic regions of the GJB2 gene have not been described thoroughly in the Sakha Republic (Yakutia), which is located in a subarctic region in Russia. The complete sequencing of the non-coding and coding regions of the GJB2 gene was performed in 393 patients with HI (Yakuts—296, Russians—51, mixed and other ethnicities—46) and in 187 normal hearing individuals of Yakut (n = 107) and Russian (n = 80) populations. In the total sample (n = 580), we revealed 12 allelic variants of the GJB2 gene, 8 of which were recessive pathogenic variants. Ten genotypes with biallelic recessive pathogenic variants in the GJB2 gene (in a homozygous or a compound heterozygous state) were found in 192 out of 393 patients (48.85%). We found that the most frequent GJB2 pathogenic variant in the Yakut patients was c.-23+1G>A (51.82%) and that the second most frequent was c.109G>A (2.37%), followed by c.35delG (1.64%). Pathogenic variants с.35delG (22.34%), c.-23+1G>A (5.31%), and c.313_326del14 (2.12%) were found to be the most frequent among the Russian patients. The carrier frequencies of the c.-23+1G>A and с.109G>A pathogenic variants in the Yakut control group were 10.20% and 2.80%, respectively. The carrier frequencies of с.35delG and c.101T>C were identical (2.5%) in the Russian control group. We found that the contribution of the GJB2 gene pathogenic variants in HI in the population of the Sakha Republic (48.85%) was the highest among all of the previously studied regions of Asia. We suggest that extensive accumulation of the c.-23+1G>A pathogenic variant in the indigenous Yakut population (92.20% of all mutant chromosomes in patients) and an extremely high (10.20%) carrier frequency in the control group may indicate a possible selective advantage for the c.-23+1G>A carriers living in subarctic climate.

Comparison of Balance Between Young Adults With and Without Hearing Impairment

Damaged vestibular system is one of the major causes of hearing impairment (HI), affects 1 to 6/1000 newborns in the United States, and is associated with balance impairment. Balance deficits may interfere with the development of motor skills. Studies have shown that balance in children with HI improves until adolescence. Few studies have investigated whether balance is impaired in young adults with HI and there results are inconsistent. PURPOSE: To compare balance between young adults with and without HI. METHODS: A total of 35 participants with HI and 35 control participants without HI (25.5 ± 3.56 years) were recruited for this study. Balance outcomes were assessed by using computerized dynamic posturography and long forceplate (NeuroCom Internationa, Clackmas, OR, 2010). Balance tests included sensory organization test (SOT), motor control test (MCT), adaptation test (AT), and unilateral stance (US). Independent T-tests were used to analyze differences in balance between young adults with and without HI. RESULTS: The study is ongoing and to date 16 participants have completed the study. Significant differences were found in the SOT composite score between those with and without HI (HI: 67± 13.62; Control 79.75± 7.30; p<.05). When the tests required the use of the vestibular system to maintain balance, the results indicate significant impairment for participants with HI. This was evident when balancing on an unstable surface with eyes closed [EC] (HI: 46.96 ± 25.66; Control: 67.62 ± 11.38) as well as balancing on an unstable surface with incorrect visual information (HI: 37.29 ± 26.04; Control: 69.95 ± 15.51). A significant difference was also found in the single leg stance EC condition on both legs. The participants with HI showed significantly higher sway velocity (degree/sec) during EC conditions (LF: 4.92 ± 0.67; RT: 6.79 ± 2.85), which indicates unstable balance compared to controls. No difference was found between the two groups for the MCT and AT. CONCLUSION: The results showed that there are differences between young adults with and without HI. When a test required the use of the vestibular system, the balance of participants with HI was less stable compared to adults without HI.

Pediatric otitis media in Fiji: Survey findings 2015

ObjectiveOtitis media (OM), as a common infectious disease, is a major cause of hearing impairment among the general population. OM remains a major public health threat in the Pacific islands, but the risks of OM have not been thoroughly explored in this region. The objective of this study is to investigate the prevalence, clinical features, and quality-of-life impacts of OM in Fiji. MethodsIn the medical service trip entitled “Healing and Hope – Taiwan Cathay Heart and Hearing Medical Mission to Fiji” (TCHHMMF), we conducted a cross-sectional OM survey study in Suva and Sigatoka areas (Korolevu, Cuvu, and Lomawai) in the summer of 2015. The otitis media – 6 (OM-6) was used to survey the OM-related quality of life. ResultsIn the 467 pediatric patients (aged 0–18 years old) screened, 13 (2.78%) have acute otitis media (AOM), 37 (7.92%) have otitis media with effusion (OME), and 19 (4.1%) have chronic otitis media (COM). Age (OR 0.53, 95% CI: 0.36–0.77) is a significant predictor of AOM, whereas male gender (OR 2.46, 95% CI: 1.13–5.37), smoke exposure (OR 2.81, 95% CI: 1.01–7.82), and concomitant chronic sinusitis (OR 6.05, 95% CI: 2.31–15.88) are significant predictors of OME. The mean OM-6 item scores are highest in caregiver concerns (3.8), physical suffering (3.7), and hearing loss (3.4) domains. ConclusionOM is an important primary care disease in Fiji that remains under-served. It is critical to educate professionals, parents, and patients to detect and to improve care for OM.

Hearing Impairment in a Semi-urban Community in North-Western Nigeria

Population based studies to measure the burden of hearing impairment are scarce in sub-Saharan Africa due largely to lack of allocation of resources. This study aims to report the prevalence and possible causes of hearing impairment in a semi-urban community. A cross-sectional community based survey using the World Health Organization Ear and Hearing disorders survey protocol was conducted in 2013. Adults and children hearing assessment was conducted via Pure-tone audiometry for air conduction thresholds at 0.5-4kHz with otoscopy. Ambient noise level was at 45dB. A total of 91 participants were tested with a hearing loss prevalence of 29(31.9%). Fifty three (58.2%) were females, population age range was 5-60years, with a mean age of 14.13years (SD: 13.51). Ear diseases were a major contributor to hearing loss 61(67.0%) affecting 5-14year old age-group, followed by unknown causes 19(20.9%). Other major causes of hearing impairment in this cohort were infectious diseases 8(8.8%), genetic conditions 2 (2.2%) and non-infectious conditions 1(1.1%) respectively. There was a significant difference in mean audiometric thresholds for the right and left ears respectively. The prevalence of hearing impairment in this community may indeed be quite high and calls for concerted efforts by relevant authorities to reduce the burden in our communities.

Mono-allelic mutations of SLC26A4 is over-presented in deaf patients with non-syndromic enlarged vestibular aqueduct

ObjectivesRecessive mutations of SLC26A4 are the major cause of hearing impairment associated with enlarged vestibular aqueduct (EVA). In a significant percentage of non-syndromic EVA patients, however, only mono-allelic mutations of SLC26A4 can be identified. In this study, we aimed to evaluate whether presence of mono-allelic mutations of SLC26A4 in those patients was coincidental or etiologically associated with the disorder. MethodsThe exons and flanking splicing sites of SLC26A4 were sequenced in 150 Chinese Han deaf probands with non-syndromic EVA. c.919-2A >G and p.H723R, two frequent mutations of SLC26A4 in Chinese Hans, were screened by an allele-specific PCR-based array in 3056 ethnically-matched normal hearing controls. The frequency of mono-allelic c.919-2A >G and p.H723R mutations was determined in each group. The statistical significance of the difference was analyzed by Fisher′s exact test. ResultsBi-allelic, mono-allelic and no mutation of SLC26A4 were detected in 98 (65.3%), 18 (12%) and 34 (22.67%) deaf probands with non-syndromic EVA, respectively. The frequency of mono-allelic c.919-2A >G and p.H723R mutations were significantly higher in the 150 deaf probands with non-syndromic EVA (8.67%) than in the 3056 normal hearing controls (1.4%, P=1.8×10−6). ConclusionPresence of mono-allelic mutations of SLC26A4 in non-syndromic EVA patients is etiologically associated with this disorder. Additional genetic or environmental causes may be present in those patients and demand further investigation and consideration during the genetic diagnosis and counseling.

Inhibition of H3K4me2 Demethylation Protects Auditory Hair Cells from Neomycin-Induced Apoptosis.

Aminoglycoside-induced hair cell loss is a major cause of hearing impairment in children and deserves more attention in medical research. Epigenetic mechanisms have been shown to protect hair cells from ototoxic drugs. In this study, we focused on the role of dimethylated histone H3K4 (H3K4me2) in hair cell survival. To investigate the effects of lysine-specific demethylase 1 (LSD1)--the histone demethylase primarily responsible for demethylating H3K4me2--on neomycin-induced hair cell loss, isolated cochleae were pretreated with LSD1 inhibitors followed by neomycin exposure. There was a severe loss of hair cells in the organ of Corti after neomycin exposure, and inhibition of LSD1 significantly protected against neomycin-induced hair cell loss. H3K4me2 expression in the nuclei of hair cells decreased after exposure to neomycin, and blocking the decreased expression of H3K4me2 with LSD1 inhibitors prevented hair cell loss. Local delivery of these inhibitors in vivo also protected hair cells from neomycin-induced ototoxicity and maintained the hearing threshold in mice as determined by auditory brain stem response. This inhibition of neomycin-induced apoptosis occurs via reduced caspase-3 activation. Together, our findings demonstrate the protective role for H3K4me2 against neomycin-induced hair cell loss and hearing loss.