ResearchPad - hearing-disorders https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[A genome-wide association study of deafness in three canine breeds]]> https://www.researchpad.co/article/elastic_article_14705 Congenital deafness in the domestic dog is usually related to the presence of white pigmentation, which is controlled primarily by the piebald locus on chromosome 20 and also by merle on chromosome 10. Pigment-associated deafness is also seen in other species, including cats, mice, sheep, alpacas, horses, cows, pigs, and humans, but the genetic factors determining why some piebald or merle dogs develop deafness while others do not have yet to be determined. Here we perform a genome-wide association study (GWAS) to identify regions of the canine genome significantly associated with deafness in three dog breeds carrying piebald: Dalmatian, Australian cattle dog, and English setter. We include bilaterally deaf, unilaterally deaf, and matched control dogs from the same litter, phenotyped using the brainstem auditory evoked response (BAER) hearing test. Principal component analysis showed that we have different distributions of cases and controls in genetically distinct Dalmatian populations, therefore GWAS was performed separately for North American and UK samples. We identified one genome-wide significant association and 14 suggestive (chromosome-wide) associations using the GWAS design of bilaterally deaf vs. control Australian cattle dogs. However, these associations were not located on the same chromosome as the piebald locus, indicating the complexity of the genetics underlying this disease in the domestic dog. Because of this apparent complex genetic architecture, larger sample sizes may be needed to detect the genetic loci modulating risk in piebald dogs.

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<![CDATA[Misophonia: Phenomenology, comorbidity and demographics in a large sample]]> https://www.researchpad.co/article/N4224db8b-e824-4eb2-b1dc-d3c3ccfee32c

Objective

Analyze a large sample with detailed clinical data of misophonia subjects in order to determine the psychiatric, somatic and psychological nature of the condition.

Methods

This observational study of 779 subjects with suspected misophonia was conducted from January 2013 to May 2017 at the outpatient-clinic of the Amsterdam University Medical Centers, location AMC, the Netherlands. We examined DSM-IV diagnoses, results of somatic examination (general screening and hearing tests), and 17 psychological questionnaires (e.g., SCL-90-R, WHOQoL).

Results

The diagnosis of misophonia was confirmed in 575 of 779 referred subjects (74%). In the sample of misophonia subjects (mean age, 34.17 [SD = 12.22] years; 399 women [69%]), 148 (26%) subjects had comorbid traits of obsessive-compulsive personality disorder, 58 (10%) mood disorders, 31 (5%) attention-deficit (hyperactivity) disorder, and 14 (3%) autism spectrum conditions. Two percent reported tinnitus and 1% hyperacusis. In a random subgroup of 109 subjects we performed audiometry, and found unilateral hearing loss in 3 of them (3%). Clinical neurological examination and additional blood test showed no abnormalities. Psychological tests revealed perfectionism (97% CPQ>25) and neuroticism (stanine 7 NEO-PI-R). Quality of life was heavily impaired and associated with misophonia severity (rs (184) = -.34 p = < .001, p = < .001).

Limitations

This was a single site study, leading to possible selection–and confirmation bias, since AMC-criteria were used.

Conclusions

This study with 575 subjects is the largest misophonia sample ever described. Based on these results we propose a set of revised criteria useful to diagnose misophonia as a psychiatric disorder.

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<![CDATA[Variants encoding a restricted carboxy-terminal domain of SLC12A2 cause hereditary hearing loss in humans]]> https://www.researchpad.co/article/Nd1837fa5-7737-42fc-aa07-ce2092d99c03

Hereditary hearing loss is challenging to diagnose because of the heterogeneity of the causative genes. Further, some genes involved in hereditary hearing loss have yet to be identified. Using whole-exome analysis of three families with congenital, severe-to-profound hearing loss, we identified a missense variant of SLC12A2 in five affected members of one family showing a dominant inheritance mode, along with de novo splice-site and missense variants of SLC12A2 in two sporadic cases, as promising candidates associated with hearing loss. Furthermore, we detected another de novo missense variant of SLC12A2 in a sporadic case. SLC12A2 encodes Na+, K+, 2Cl cotransporter (NKCC) 1 and plays critical roles in the homeostasis of K+-enriched endolymph. Slc12a2-deficient mice have congenital, profound deafness; however, no human variant of SLC12A2 has been reported as associated with hearing loss. All identified SLC12A2 variants mapped to exon 21 or its 3’-splice site. In vitro analysis indicated that the splice-site variant generates an exon 21-skipped SLC12A2 mRNA transcript expressed at much lower levels than the exon 21-included transcript in the cochlea, suggesting a tissue-specific role for the exon 21-encoded region in the carboy-terminal domain. In vitro functional analysis demonstrated that Cl influx was significantly decreased in all SLC12A2 variants studied. Immunohistochemistry revealed that SLC12A2 is located on the plasma membrane of several types of cells in the cochlea, including the strial marginal cells, which are critical for endolymph homeostasis. Overall, this study suggests that variants affecting exon 21 of the SLC12A2 transcript are responsible for hereditary hearing loss in humans.

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<![CDATA[Subunits of the mechano-electrical transduction channel, Tmc1/2b, require Tmie to localize in zebrafish sensory hair cells]]> https://www.researchpad.co/article/5c648d15d5eed0c484c81f40

Mutations in transmembrane inner ear (TMIE) cause deafness in humans; previous studies suggest involvement in the mechano-electrical transduction (MET) complex in sensory hair cells, but TMIE’s precise role is unclear. In tmie zebrafish mutants, we observed that GFP-tagged Tmc1 and Tmc2b, which are subunits of the MET channel, fail to target to the hair bundle. In contrast, overexpression of Tmie strongly enhances the targeting of Tmc1-GFP and Tmc2b-GFP to stereocilia. To identify the motifs of Tmie underlying the regulation of the Tmcs, we systematically deleted or replaced peptide segments. We then assessed localization and functional rescue of each mutated/chimeric form of Tmie in tmie mutants. We determined that the first putative helix was dispensable and identified a novel critical region of Tmie, the extracellular region and transmembrane domain, which is required for both mechanosensitivity and Tmc2b-GFP expression in bundles. Collectively, our results suggest that Tmie’s role in sensory hair cells is to target and stabilize Tmc channel subunits to the site of MET.

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<![CDATA[A comparison of the Muenster, SIOP Boston, Brock, Chang and CTCAEv4.03 ototoxicity grading scales applied to 3,799 audiograms of childhood cancer patients treated with platinum-based chemotherapy]]> https://www.researchpad.co/article/5c6f1527d5eed0c48467ae60

Childhood cancer patients treated with platinums often develop hearing loss and the degree is classified according to different scales globally. Our objective was to compare concordance between five well-known ototoxicity scales used for childhood cancer patients. Audiometric test results (n = 654) were evaluated longitudinally and graded according Brock, Chang, International Society of Pediatric Oncology (SIOP) Boston, Muenster scales and the U.S. National Cancer Institute Common Technology Criteria for Adverse Events (CTCAE) version 4.03. Adverse effects of grade 2, 3 and 4 are considered to reflect a degree of hearing loss sufficient to interfere with day-to-day communication (> = Chang grade 2a; > = Muenster grade 2b). We term this “deleterious hearing loss”. A total number of 3,799 audiograms were evaluated. The prevalence of deleterious hearing loss according to the last available audiogram of each patient was 59.3% (388/654) according to Muenster, 48.2% (315/653) according to SIOP, 40.5% (265/652) according to Brock, 40.3% (263/652) according to Chang, and 57.5% (300/522) according to CTCAEv4.03. Overall concordance between the scales ranged from ĸ = 0.636 (Muenster vs. Chang) to ĸ = 0.975 (Brock vs. Chang). Muenster detected hearing loss the earliest in time, followed by Chang, SIOP and Brock. Generally good concordance between the scales was observed but there is still diversity in definitions of functional outcomes, such as differences in distribution levels of severity of hearing loss, and additional intermediate scales taking into account losses <40 dB as well. Regardless of the scale used, hearing function decreases over time and therefore, close monitoring of hearing function at baseline and with each cycle of platinum therapy should be conducted.

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<![CDATA[Visual habituation in deaf and hearing infants]]> https://www.researchpad.co/article/5c648d4bd5eed0c484c824a4

Early cognitive development relies on the sensory experiences that infants acquire as they explore their environment. Atypical experience in one sensory modality from birth may result in fundamental differences in general cognitive abilities. The primary aim of the current study was to compare visual habituation in infants with profound hearing loss, prior to receiving cochlear implants (CIs), and age-matched peers with typical hearing. Two complementary measures of cognitive function and attention maintenance were assessed: the length of time to habituate to a visual stimulus, and look-away rate during habituation. Findings revealed that deaf infants were slower to habituate to a visual stimulus and demonstrated a lower look-away rate than hearing infants. For deaf infants, habituation measures correlated with language outcomes on standardized assessments before cochlear implantation. These findings are consistent with prior evidence suggesting that habituation and look-away rates reflect efficiency of information processing and may suggest that deaf infants take longer to process visual stimuli relative to the hearing infants. Taken together, these findings are consistent with the hypothesis that hearing loss early in infancy influences aspects of general cognitive functioning.

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<![CDATA[Complex tone stimulation may induce binaural diplacusis with low-tone hearing loss]]> https://www.researchpad.co/article/5c57e67ad5eed0c484ef339d

To clarify the possible mechanism causing binaural diplacusis with low-tone hearing loss, two psychoacoustic experiments were performed with 20 healthy subjects, using harmonic complex tones. In the first experiment, two tones were presented unilaterally, either from the right or left side. One of the tones presented was higher in frequency in terms of the fundamental component, but lower or equal in frequency in terms of the highest component, than the other tone. The subjects were asked which tone was higher in pitch after listening to both tones. They were also asked to compare tones in which low-tone components were eliminated. In the second experiment, the subjects heard these complex tones binaurally, with low-tone components eliminated in one ear. In the first experiment, most subjects perceived pitch direction, that is, higher or lower, in a reverse way when low-tone components were eliminated from the complex tones. In the second experiment, approximately half of all subjects heard the tones at different pitches in both ears. Under certain conditions, complex tone stimulation may induce binaural diplacusis when low-tone hearing is lost in one ear.

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<![CDATA[Mutation screening in non-syndromic hearing loss patients with cochlear implantation by massive parallel sequencing in Taiwan]]> https://www.researchpad.co/article/5c79b005d5eed0c4841e3c60

Objectives

To explore the molecular epidemiology of rare deafness genes in Taiwanese sensorineural hearing impairment (SNHI) patients with cochlear implantation (CI) by performing massive parallel sequencing (MPS) and correlating genetic factors and CI outcomes.

Methods

We enrolled 41 Taiwanese non-syndromic deafness patients with CI that lacked known mutations in common deafness genes. All probands were screened by a targeted exon amplification method that used massively parallel sequencing to screen a customized panel that included 40 relatively rare non-syndromic deafness genes.

Results

Thirteen candidate variants in nine relatively rare deafness genes (MYO15A, TMC1, MYH14, MYO3A, ACTG1, COL11A2, DSPP, GRHL2, and WFS1) were identified in 24.4% (10/41) of the non-syndromic deafness probands with CI. According to the ACMG Standards and Guidelines, five variants in MYO15A and ACTG1 were classified as likely pathogenic variants. Two of three multi-generational pedigrees exhibiting deafness were analyzed for the segregation of the disorder with the possible disease-causing variants. Patients with variants detected in most of the identified variant-bearing genes showed relatively good CI outcomes.

Conclusions

We successfully identified candidate variants in partially deaf Taiwanese probands who lacked the known mutations in common deafness genes. Comparing the progress of hearing rehabilitation in CI patients with their apparent causative variants and the expression profiles of their altered genes allowed us to speculate on how alterations in specific gene sets may influence outcomes in hearing rehabilitation after CI.

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<![CDATA[Bilateral delayed endolymphatic hydrops evaluated by bilateral intratympanic injection of gadodiamide with 3T-MRI]]> https://www.researchpad.co/article/5c117b60d5eed0c484698ee1

The purpose of this study was to assess the diagnostic performance of 3T MRI after intratympanic injection of gadodiamide for delayed endolymphatic hydrops (DEH), and assess the relationship between endolymphatic hydrops (ELH) and vestibular function in patients diagnosed with DEH and confirmed by 3T MRI. Nineteen patients clinically diagnosed with DEH (11 ipsilateral DEH, 8 contralateral DEH) participated in this study. Diluted gadodiamide was administered to the bilateral tympanic cavity by injection through the tympanic membrane. At 24 hours post-injection, the ELH was evaluated by MRI. Patient vestibular functions were evaluated by caloric testing and cVEMP. ELH was observed in all patients (19/19: positive rate 100%). The distribution patterns of ELH varied between the cochlear or vestibular region. Vestibular ELH was observed in the affected ear in all ipsilateral DEH patients. In the contralateral DEH patients, however, there were individual differences in the distribution patterns of ELH. Six patients (1 ipsilateral DEH, 5 contralateral DEH) had bilateral ELH. No obvious relationships were observed between ELH and vestibular function. ELH distribution was complicated, particularly in the contralateral DEH cases. It was difficult to identify the existence of ELH by vestibular functional testing alone; therefore, 3T MRI is thought to be useful for identifying the affected ear. A significant number of cases had “bilateral” DEH, particularly among the contralateral DEH cases, indicating that we should pay careful attention to this pathology when treating DEH.

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<![CDATA[BOLD fMRI effects of transcutaneous vagus nerve stimulation in patients with chronic tinnitus]]> https://www.researchpad.co/article/5c084232d5eed0c484fcc23d

Objective

Vagus nerve stimulation (VNS) is a neuromodulation method used for treatment of epilepsy and depression. Transcutaneous VNS (tVNS) has been gaining popularity as a noninvasive alternative to VNS. Previous tVNS neuroimaging studies revealed brain (de)activation patterns that involved multiple areas implicated in tinnitus generation and perception. In this study, functional magnetic resonance imaging (fMRI) was used to explore the effects of tVNS on brain activity in patients with tinnitus.

Methods

Thirty-six patients with chronic tinnitus received tVNS to the inner tragus, cymba conchae, and earlobe (sham stimulation).

Results

The locus coeruleus and nucleus of the solitary tract in the brainstem were activated in response to stimulation of both locations compared with the sham stimulation. The cochlear nuclei were also activated, which was not observed in healthy subjects with normal hearing. Multiple auditory and limbic structures, as well as other brain areas associated with generation and perception of tinnitus, were deactivated by tVNS, particularly the parahippocampal gyrus, which was recently speculated to cause tinnitus in hearing-impaired patients.

Conclusions

tVNS via the inner tragus or cymba conchae suppressed neural activity in the auditory, limbic, and other tinnitus-related non-auditory areas through auditory and vagal ascending pathways in tinnitus patients. The results from this study are discussed in the context of several existing models of tinnitus. They indicate that the mechanism of action of tVNS might be involved in multiple brain areas responsible for the generation of tinnitus, tinnitus-related emotional annoyance, and their mutual reinforcement.

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<![CDATA[Arsenic level in toenails is associated with hearing loss in humans]]> https://www.researchpad.co/article/5b4a1966463d7e428027f8af

Arsenic (As) pollution in drinking water is a worldwide health risk for humans. We previously showed hearing loss in young people who live in areas of As-polluted drinking water and in young mice orally treated with As. In this study, we epidemiologically examined associations between As levels in toenails and hearing in 145 Bangladeshi aged 12–55 years in 2014. Levels of As in toenails, but not those in urine, were shown to be significantly correlated with hearing loss at 4 kHz [odds ratio (OR) = 4.27; 95% confidence interval (CI): 1.51, 12.05], 8 kHz (OR = 3.91; 95% CI: 1.47, 10.38) and 12 kHz (OR = 4.15; 95% CI: 1.55, 11.09) by multivariate analysis with adjustments for age, sex, smoking and BMI. Our experimental study further showed a significant association between As levels in inner ears and nails (r = 0.8113, p = 0.0014) in mice orally exposed to As, suggesting that As level in nails is a suitable index to assess As level in inner ears. Taken together, the results of our study suggest that As level in nails could be a convenient and non-invasive biomarker for As-mediated hearing loss in humans.

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<![CDATA[Functional reorganization of the conceptual brain system after deafness in early childhood]]> https://www.researchpad.co/article/5b4a196d463d7e428027f8b3

The neurodevelopmental consequences of deafness on the functional neuroarchitecture of the conceptual system have not been intensively investigated so far. Using functional magnetic resonance imaging (fMRI), we therefore identified brain areas involved in conceptual processing in deaf and hearing participants. Conceptual processing was probed by a pictorial animacy decision task. Furthermore, brain areas sensitive to observing verbal signs and to observing non-verbal visual hand actions were identified in deaf participants. In hearing participants, brain areas responsive to environmental sounds and the observation of visual hand actions were determined. We found a stronger recruitment of superior and middle temporal cortex in deaf compared to hearing participants during animacy decisions. This region, which forms auditory cortex in hearing people according to the sound listening task, was also activated in deaf participants, when they observed sign language, but not when they observed non-verbal hand actions. These results indicate that conceptual processing in deaf people more strongly depends on language representations compared to hearing people. Furthermore, additionally enhanced activation in visual and motor areas of deaf versus hearing participants during animacy decisions and a more frequent report of visual and motor features in the property listing task suggest that the loss of the auditory channel is partially compensated by an increased importance of visual and motor information for constituting object knowledge. Hence, our results indicate that conceptual processing in deaf compared to hearing people is more strongly based on the language system, complemented by an enhanced contribution of the visuo-motor system.

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<![CDATA[The Effects of Sensorineural Hearing Impairment on Asynchronous Glimpsing of Speech]]> https://www.researchpad.co/article/5989dab1ab0ee8fa60bab4eb

In a previous study with normal-hearing listeners, we evaluated consonant identification masked by two or more spectrally contiguous bands of noise, with asynchronous square-wave modulation applied to neighboring bands. Speech recognition thresholds were 5.1–8.5 dB better when neighboring bands were presented to different ears (dichotic) than when all bands were presented to one ear (monaural), depending on the spectral width of the frequency bands. This dichotic advantage was interpreted as reflecting masking release from peripheral spread of masking from neighboring frequency bands. The present study evaluated this effect in listeners with sensorineural hearing loss, a population more susceptible to spread of masking. Speech perception (vowel-consonant-vowel stimuli, as in /aBa/) was measured in the presence of fluctuating noise that was either modulated synchronously across frequency or asynchronously. Hearing-impaired listeners (n = 9) and normal-hearing controls were tested at either the same intensity (n = 7) or same sensation level (n = 8). Hearing-impaired listeners had mild-to-moderate hearing loss and symmetrical, flat audiometric thresholds. While all groups of listeners performed better in the dichotic than monaural condition, this effect was smaller for the hearing-impaired (3.5 dB) and equivalent-sensation-level controls (3.3 dB) than controls tested at the same intensity (11.0 dB). The present study is consistent with the idea that dichotic presentation can improve speech-in-noise listening for hearing-impaired listeners, and may be enhanced when combined with amplification.

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<![CDATA[Screening of MITF and SOX10 Regulatory Regions in Waardenburg Syndrome Type 2]]> https://www.researchpad.co/article/5989d9d6ab0ee8fa60b6601f

Waardenburg syndrome (WS) is a rare auditory-pigmentary disorder that exhibits varying combinations of sensorineural hearing loss and pigmentation defects. Four subtypes are clinically defined based on the presence or absence of additional symptoms. WS type 2 (WS2) can result from mutations within the MITF or SOX10 genes; however, 70% of WS2 cases remain unexplained at the molecular level, suggesting that other genes might be involved and/or that mutations within the known genes escaped previous screenings. The recent identification of a deletion encompassing three of the SOX10 regulatory elements in a patient presenting with another WS subtype, WS4, defined by its association with Hirschsprung disease, led us to search for deletions and point mutations within the MITF and SOX10 regulatory elements in 28 yet unexplained WS2 cases. Two nucleotide variations were identified: one in close proximity to the MITF distal enhancer (MDE) and one within the U1 SOX10 enhancer. Functional analyses argued against a pathogenic effect of these variations, suggesting that mutations within regulatory elements of WS genes are not a major cause of this neurocristopathy.

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<![CDATA[Eye Gaze during Observation of Static Faces in Deaf People]]> https://www.researchpad.co/article/5989da20ab0ee8fa60b7eb33

Knowing where people look when viewing faces provides an objective measure into the part of information entering the visual system as well as into the cognitive strategy involved in facial perception. In the present study, we recorded the eye movements of 20 congenitally deaf (10 male and 10 female) and 23 (11 male and 12 female) normal-hearing Japanese participants while they evaluated the emotional valence of static face stimuli. While no difference was found in the evaluation scores, the eye movements during facial observations differed among participant groups. The deaf group looked at the eyes more frequently and for longer duration than the nose whereas the hearing group focused on the nose (or the central region of face) more than the eyes. These results suggest that the strategy employed to extract visual information when viewing static faces may differ between deaf and hearing people.

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<![CDATA[Evaluation of Audiometric Test Results to Determine Hearing Impairment in Patients with Rheumatoid Arthritis: Analysis of Data from the Korean National Health and Nutrition Examination Survey]]> https://www.researchpad.co/article/5989da71ab0ee8fa60b950e3

This study aimed to evaluate the association between rheumatoid arthritis (RA) and hearing impairment in the Korean adult population. Audiometric and laboratory test data from the 2010–2012 Korean National Health and Nutrition Examination Survey (KNHANES) were used for analysis. The relationship between RA and hearing impairment was analyzed, adjusting for various known risk factors associated with hearing impairment. RA was defined in the questionnaire as “RA diagnosed by a physician (yes/no) through a standardized interview.” We defined hearing impairment according to 2 categories of frequency (low/mid and high) as follows (average values in kHz): low/mid frequency, 0.5, 1.0, and 2.0, and high frequency, 3.0, 4.0, and 6.0. Of the subjects, 15,158 (weighted n = 32,035,996) completed the audiometric tests. The overall weighted prevalence of RA was 1.5%. The prevalence of hearing impairment was higher in the subjects with RA than in those without RA, in both, the low/mid- and high-frequency categories (21.1% vs 7.5%, p < 0.001 and 43.3% vs. 26.2%, p < 0.001, respectively). In the multivariable logistic analysis, RA (odds ratios [OR] 1.47, 95% confidence interval [CI] 1.05–2.06, p = 0.025) was an independent risk factor of low/mid-frequency hearing impairment along with age (OR 1.12, 95% CI 1.12–1.13, p < 0.001), current smoking (OR 1.27, 95% CI 1.03–1.56, p = 0.026), and college graduation (OR 0.53, 95% CI 0.39–0.72, p < 0.001). In the multivariable analysis of high-frequency hearing impairment, RA did not show any association with hearing impairment. This study suggests that RA is associated with low/mid-frequency hearing impairment after adjustment for various known risk factors. Further study is needed to verify the hearing impairment in RA.

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<![CDATA[Health-Related Quality of Life in Korean Adults with Hearing Impairment: The Korea National Health and Nutrition Examination Survey 2010 to 2012]]> https://www.researchpad.co/article/5989db3eab0ee8fa60bd5d22

Background

As the global population ages, disabling hearing impairment (HI) have been increased rapidly. The impact of HI on health-related quality of life (HRQoL) is of great importance to aid the development of strategic plans and to guide therapeutic interventions.

Purpose

To evaluate HRQoL in Korean adults with different degrees of HI using EuroQol five-dimensional (EQ-5D) and EQ-visual analogue scale (VAS), the preference-based generic measures of HRQoL.

Methods

Using a representative dataset from the Korea National Health and Nutrition Examination Survey (KNHANES) from January 2010 to December 2012, EQ-5D questionnaire and EQ- VAS scores of subjects with HI were compared with those of subjects without HI. Logistic regression analysis, with adjustment for covariates, was used to evaluate the impact of HI on HRQoL scales. HI was defined according to the hearing thresholds of pure-tone averages at 0.5, 1, 2, and 3 kHz of the better hearing ear as follows; mild HI (26 to < 40 dB) and moderate to severe HI (≥ 40 dB).

Results

Of the 16,449 Korean adults in KNHANES (age, 45.0 ± 0.2 years; male, 49.7%), 1757 (weighted prevalence, 7.6%) had mild HI and 890 (3.6%) had moderate to severe HI. Subjects with HI had impaired HRQoL as compared with subjects without HI (EQ-5D, 0.96 ± 0.00 vs. 0.88±0.00 vs. 0.86 ± 0.01 for control vs. mild HI vs. moderate to severe HI, p < 0.001; EQ-VAS, 75.10 ± 0.18 vs. 67.48 ± 0.63 vs. 66.24 ± 0.92 for control vs. mild HI vs. moderate to severe HI, p < 0.001). After adjusting for socio-demographic factors (age, gender, household income, education level, presence of spouse) and health-related behaviors (smoking status, alcohol intake, regular exercise), psychological stress, and the presence of comorbidities (diabetes, hypercholesterolemia, hypertension, decreased eGFR, and tinnitus), EQ-VAS remained impaired in the moderate to severe HI group (61.72±1.69) as compared with the control group (65.68 ± 1.26, p = 0.004), but EQ-5D impairment disappeared (0.86 ± 0.02 vs.0.88±0.01 for moderate to severe HI vs. control, p = 0.058).

Conclusion

After adjusting for socio-demographic and psychosocial factors and comorbidities, Korean adults with moderate to severe HI rated their health statuses lower than subjects without HI.

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<![CDATA[Silent Damage of Noise on Cochlear Afferent Innervation in Guinea Pigs and the Impact on Temporal Processing]]> https://www.researchpad.co/article/5989d9dbab0ee8fa60b67aca

Noise-exposure at levels low enough to avoid a permanent threshold shift has been found to cause a massive, delayed degeneration of spiral ganglion neurons (SGNs) in mouse cochleae. Damage to the afferent innervation was initiated by a loss of synaptic ribbons, which is largely irreversible in mice. A similar delayed loss of SGNs has been found in guinea pig cochleae, but at a reduced level, suggesting a cross-species difference in SGN sensitivity to noise. Ribbon synapse damage occurs “silently” in that it does not affect hearing thresholds as conventionally measured, and the functional consequence of this damage is not clear. In the present study, we further explored the effect of noise on cochlear afferent innervation in guinea pigs by focusing on the dynamic changes in ribbon counts over time, and resultant changes in temporal processing. It was found that (1) contrary to reports in mice, the initial loss of ribbons largely recovered within a month after the noise exposure, although a significant amount of residual damage existed; (2) while the response threshold fully recovered in a month, the temporal processing continued to be deteriorated during this period.

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<![CDATA[In Rural Eastern Ethiopia Hearing Loss Is the Most Frequent Disability during Childhood: A Community Based Survey]]> https://www.researchpad.co/article/5989d9f3ab0ee8fa60b6f0aa

Background

The type and extent of childhood disability in Ethiopia is unknown due to lack of accurate and reliable data. This study tried to assess the magnitude and types of disabilities among children 0–14 years of age in eastern Ethiopia.

Methods

We conducted a cross-sectional community-based study among households that are under demographic and health surveillance in eastern Ethiopia. The study population consisted of all children aged 0–14 year. A structured questionnaire was used to assess the type and severity of the disability.

Results

A total of 21,572 children in the age group 0–14 were screened for disability. Of which 586 (2.7%; 95% CI = 2.5%, 2.9%) had at least one kind of disability at the time of the survey. The proportion of disability increased as children were older; measured by the extended Mantel-Haenszel (M-H) chi square for linear trend (M-H = 48.74; P<0.001). Hearing impairment was the most common reported disability; 417 (71.2%; 95% CI = 67.5%, 74.9%). Among children with a disability, 179 (31.0%; 95% CI = 27.3%, 34.7%) had a combination of multiple disabilities and about a third, 200 (34.1%; 95% CI = 30.3%, 37.9%) had developed the disability during infancy. Magnitude of disability was higher among boys 335 (2.98%; 95% CIs = 2.66%, 3.30%) compared to girls 251 (2.44%; 95% CIs = 2.14%, 2.74%).

Conclusion

Childhood disability is a health challenge in the study area and is already common at an early age. Permanent disability among children may be prevented by an early screening program in the routine child health services and adequate care, especially for hearing impairment.

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<![CDATA[Direct Acoustic Stimulation at the Lateral Canal: An Alternative Route to the Inner Ear?]]> https://www.researchpad.co/article/5989da11ab0ee8fa60b7995c

Severe to profound mixed hearing loss is associated with hearing rehabilitation difficulties. Recently, promising results for speech understanding were obtained with a direct acoustic cochlear implant (DACI). The surgical implantation of a DACI with standard coupling through a stapedotomy can however be regarded as challenging. Therefore, in this experimental study, the feasibility of direct acoustic stimulation was investigated at an anatomically and surgically more accessible inner ear site. DACI stimulation of the intact, blue-lined and opened lateral semicircular canal (LC) was investigated and compared with standard oval window (OW) coupling. Additionally, stapes footplate fixation was induced. Round window (RW) velocity, as a measure of the performance of the device and its coupling efficiency, was determined in fresh-frozen human cadaver heads. Using single point laser Doppler vibrometry, RW velocity could reliably be measured in low and middle frequency range, and equivalent sound pressure level (LE) output was calculated. Results for the different conditions obtained in five heads were analyzed in subsequent frequency ranges. Comparing the difference in RW membrane velocity showed higher LE in the LC opened condition [mean: 103 equivalent dB SPL], than in LC intact or blue-lined conditions [63 and 74 equivalent dB SPL, respectively]. No difference was observed between the LC opened and the standard OW condition. Inducing stapes fixation, however, led to a difference in the low frequency range of LE compared to LC opened. In conclusion, this feasibility study showed promising results for direct acoustic stimulation at this specific anatomically and surgically more accessible inner ear site. Future studies are needed to address the impact of LC stimulation on cochlear micromechanics and on the vestibular system like dizziness and risks of hearing loss.

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