Mutation in mitochondrial DNA as a cause of presbyacusis

Much of the hearing loss that occurs in old age is likely to be due to the long-term deterioration of the mitochondria in the different structures of the cochlea. The current review surveys some of the basic information on mitochondria and mitochondrial DNA, as a background to their possible involvement in presbyacusis. It is likely that oxygen radicals damage mitochondrial DNA and other components of the mitochondria, such as their proteins and lipids. This further compromises both oxidative phosphorylation and the repair processes in mitochondria, setting up a vicious cycle of degradation. Evidence is presented from inherited point mutations on the possibly most critical sites for mutations in mitochondrial DNA associated with hearing loss. It is suggested that random sorting and clonal expansion of mutations both maintain the integrity of the pool of mitochondrial DNA molecules and give rise to the apoptosis that leads to loss of vulnerable cells, and hence to deafness. It is moreover suggested that apoptosis of the vulnerable cells of the inner ear may to some extent be preventable, or at least delayed. Copyright (C) 2004 S. Karger AG, Basel.

Mutations in SNX14 cause a distinctive autosomal-recessive cerebellar ataxia and intellectual disability syndrome

Intellectual disability and cerebellar atrophy occur together in a large number of genetic conditions and are frequently associated with microcephaly and/or epilepsy. Here we report the identification of causal mutations in Sorting Nexin 14 (SNX14) found in seven affected individuals from three unrelated consanguineous families who presented with recessively inherited moderate-severe intellectual disability, cerebellar ataxia, early-onset cerebellar atrophy, sensorineural hearing loss, and the distinctive association of progressively coarsening facial features, relative macrocephaly, and the absence of seizures. We used homozygosity mapping and whole-exome sequencing to identify a homozygous nonsense mutation and an in-frame multiexon deletion in two families. A homozygous splice site mutation was identified by Sanger sequencing of SNX14 in a third family, selected purely by phenotypic similarity. This discovery confirms that these characteristic features represent a distinct and recognizable syndrome. SNX14 encodes a cellular protein containing Phox (PX) and regulator of G protein signaling (RGS) domains. Weighted gene coexpression network analysis predicts that SNX14 is highly coexpressed with genes involved in cellular protein metabolism and vesicle-mediated transport. All three mutations either directly affected the PX domain or diminished SNX14 levels, implicating a loss of normal cellular function. This manifested as increased cytoplasmic vacuolation as observed in cultured fibroblasts. Our findings indicate an essential role for SNX14 in neural development and function, particularly in development and maturation of the cerebellum.

Fratura traumática do osso temporal : diagnóstico, sequelas e tratamento

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Características sociodemográficas del adulto mayor con deterioro auditivo en el centro de atención del IESS. Cuenca 2015

OBJETIVO GENERAL: Establecer las características sociodemográficas del adulto mayor con deterioro auditivo en el centro de atención del IESS. Cuenca 2015. METODOLOGÍA: Estudio de tipo descriptivo transversal. El universo compuesto por 1800 personas que se encontraron inscritos en el centro de atención del adulto mayor, en la ciudad de Cuenca, 2015. Se trabajó con una muestra de 317 adultos mayores. Este proyecto se realizó mediante: encuestas y audiometrías. Los datos que se obtuvieron fueron analizados en SPSS 20.00 y Excel 2010; para el análisis se utilizó la estadística descriptiva; además personal capacitado realizó la audiometría de tipo tonal, en el Centro de diagnóstico de la Universidad de Cuenca. RESULTADOS: Los resultados obtenidos de las encuestas y de las audiometrías realizadas son los siguientes. De los 317 encuestados (248 (78%) femeninos, 69 (22%) masculinos), las audiometrías realizadas a 160 adultos mayores, presentan algún tipo de deterioro auditivo destacando el grado de audición normal 11% (34), hipoacusia conductiva leve 7% (22), hipoacusia conductiva moderada 3% (11), hipoacusia mixta leve 8% (25), hipoacusia mixta moderada 3% (8), hipoacusia sensorioneural leve 9% (29), hipoacusia sensorioneural moderada 9% (27), hipoacusia sensorioneural severa 1% (3). La información obtenida de la investigación permite establecer una evaluación general del estado actual del grado de audición de los adultos mayores, permite evidenciar la importancia de una atención adecuada a partir de los 60 o más años, para evitar la pérdida de audición por envejecimiento

Does cochlear implantation improve speech recognition in children with auditory neuropathy spectrum disorder? A systematic review

OBJECTIVE: Cochlear implantation (CI) is a standard treatment for severe-profound sensorineural hearing loss (SNHL). However, consensus has yet to be reached on its effectiveness for hearing loss caused by auditory neuropathy spectrum disorder (ANSD). This review aims to summarize and synthesize current evidence of the effectiveness of CI in improving speech recognition in children with ANSD. DESIGN: Systematic review. STUDY SAMPLE: A total of 27 studies from an initial selection of 237. RESULTS: All selected studies were observational in design, including case studies, cohort studies, and comparisons between children with ANSD and SNHL. Most children with ANSD achieved open-set speech recognition with their CI. Speech recognition ability was found to be equivalent in CI users (who previously performed poorly with hearing aids) and hearing-aid users. Outcomes following CI generally appeared similar in children with ANSD and SNHL. Assessment of study quality, however, suggested substantial methodological concerns, particularly in relation to issues of bias and confounding, limiting the robustness of any conclusions around effectiveness. CONCLUSIONS: Currently available evidence is compatible with favourable outcomes from CI in children with ANSD. However, this evidence is weak. Stronger evidence is needed to support cost-effective clinical policy and practice in this area.

Degree of satisfaction among hearing aid users

Introduction: Hearing loss (HL) is defined as the complete or partial loss of hearing ability. Aims: To characterize (1) the degree of satisfaction among adult and elderly hearing aid (HA) users who were treated by a public hearing health service and (2) the relationship between satisfaction and the variables of gender, age, degree of HL, and type of HA. Method: The clinical and experimental study included the administration of the Satisfaction with Amplification in Daily Life (SADL) questionnaire to 110 patients who had used HAs for more than 3 months and were 18 years of age or older. Results: Test patients were sex-balanced (48% were women) and had a mean age of 67 years. A relatively high incidence of sensorineural moderate HL was detected in the study patients (66%) and device B was the most commonly used HA type (48%). No significant differences were evident between HA satisfaction and sex. The importance placed on services/costs and personal image varied between age groups. Correlation was evident at all levels between user satisfaction and amplification. Decreased satisfaction was observed in individuals with severe and/or profound HL. The type of HA used yielded statistically significant differences in the positive effects referring. Conclusion: No correlations were evident between the different factors proposed. HA users exhibited high levels of satisfaction in all SADL areas

Low cost calibrated mechanical noisemaker for hearing screening of neonates in resource constrained settings

Background & objectives: There is a need to develop an affordable and reliable tool for hearing screening of neonates in resource constrained, medically underserved areas of developing nations. This study valuates a strategy of health worker based screening of neonates using a low cost mechanical calibrated noisemaker followed up with parental monitoring of age appropriate auditory milestones for detecting severe-profound hearing impairment in infants by 6 months of age. Methods: A trained health worker under the supervision of a qualified audiologist screened 425 neonates of whom 20 had confirmed severe-profound hearing impairment. Mechanical calibrated noisemakers of 50, 60, 70 and 80 dB (A) were used to elicit the behavioural responses. The parents of screened neonates were instructed to monitor the normal language and auditory milestones till 6 months of age. This strategy was validated against the reference standard consisting of a battery of tests - namely, auditory brain stem response (ABR), otoacoustic emissions (OAE) and behavioural assessment at 2 years of age. Bayesian prevalence weighted measures of screening were calculated. Results: The sensitivity and specificity was high with least false positive referrals for. 70 and 80 dB (A) noisemakers. All the noisemakers had 100 per cent negative predictive value. 70 and 80 dB (A) noisemakers had high positive likelihood ratios of 19 and 34, respectively. The probability differences for pre- and post- test positive was 43 and 58 for 70 and 80 dB (A) noisemakers, respectively. Interpretation & conclusions: In a controlled setting, health workers with primary education can be trained to use a mechanical calibrated noisemaker made of locally available material to reliably screen for severe-profound hearing loss in neonates. The monitoring of auditory responses could be done by informed parents. Multi-centre field trials of this strategy need to be carried out to examine the feasibility of community health care workers using it in resource constrained settings of developing nations to implement an effective national neonatal hearing screening programme.

Non-Syndromic Hearing Impairment in India: High Allelic Heterogeneity among Mutations in TMPRSS3, TMC1, USHIC, CDH23 and TMIE

Mutations in the autosomal genes TMPRSS3, TMC1, USHIC, CDH23 and TMIE are known to cause hereditary hearing loss. To study the contribution of these genes to autosomal recessive, non-syndromic hearing loss (ARNSHL) in India, we examined 374 families with the disorder to identify potential mutations. We found four mutations in TMPRSS3, eight in TMC1, ten in USHIC, eight in CDH23 and three in TMIE. Of the 33 potentially pathogenic variants identified in these genes, 23 were new and the remaining have been previously reported. Collectively, mutations in these five genes contribute to about one-tenth of ARNSHL among the families examined. New mutations detected in this study extend the allelic heterogeneity of the genes and provide several additional variants for structure-function correlation studies. These findings have implications for early DNA-based detection of deafness and genetic counseling of affected families in the Indian subcontinent.

Motor skill deficits in children with partial hearing

AIM:
We examined the effect of partial hearing, including cochlear implantation, on the development of motor skills in children (aged 6-12y).

METHOD:
Three independent groups of children were selected: a partial hearing group (n=25 [14 males, 11 females]; mean age 8y 8mo, SD 1y 10mo), a nonverbal IQ-matched group (n=27 [15 males, 12 females]; mean age 9y, SD 1y 6mo), and an age-matched group (n=26 [8 males, 18 females]; mean age 8y 8mo, SD 1y 7mo) from three schools with special units for children with partial hearing. All children with partial hearing had a bilateral hearing loss >60 decibels. Motor and balance skills were assessed using the Movement Assessment Battery for Children (MABC) and two protocols from the NeuroCom Balance Master clinical procedures.

RESULTS:
The mean standardized total MABC score of the children with partial hearing (95% confidence interval [CI] 71.8-88.7) was significantly lower than both the age-matched (95% CI 95.8-111.4; p<0.01) and the IQ-matched (95% CI 87.6-103.0; p=0.03) comparison groups. The children with partial hearing had particular difficulties with balance, most notably during tests of intersensory demand. However, subgroup analyses revealed that the effect of cochlear implantation was clearly dependent on the nature of the task.

INTERPRETATION:
Children with partial hearing are at high risk of clinical levels of motor deficit, with balance difficulties providing support for conventional vestibular deficit theory. However, the effect of cochlear implantation suggests that other sensory systems may be involved. A broader ecological perspective, which takes into account factors external to the child, may prove a useful framework for future research.

Oto-emisiones acústicas transientes en recién nacidos de alto riesgo para hipoacusia neurosensorial

La hipoacusia neurosensorial en recién nacidos es más frecuente cuando a ésta se suman factores de alto riesgo. Teniendo en |cuenta estos factores de riesgo y la aplicación de una prueba de tamizaje neonatal para detección de hipoacusias como lo son las Otoemisiones Acústicas de tipo Transientes (OEAT) se decide llevar a cabo un estudio analítico de casos y controles con el objetivo de establecer si existe alguna asociación estadísticamente significativa en donde se demuestre que el hecho de tener uno o más factores de riesgo para desarrollar hipoacusia de tipo sensorial está asociado a una respuesta fallida o ausente en las otoemisiones acústicas. El presente estudio fue llevado a cabo en el Hospital Universitario de la Samaritana en una muestra de 192 recién nacidos que tenían uno o más factores de alto riesgo para hipoacusia de tipo sensorial, a cada uno de ellos se les realizó Oto-emisiones acústicas de tipo Transientes; 176 de éstos obtuvieron un paso en la respuesta de oto-emisiones seleccionándose así como grupo control y el resto de los recién nacidos, es decir 16 de ellos, presentaron respuestas ausentes en el resultado de las otoemisiones, considerándose de esta forma como grupo de casos. Mediante pruebas de chi cuadrado, estimación de riesgo y una prueba exacta de Fisher se observó entonces que no existe correlación alguna entre tener factores de alto riesgo para hipoacusia neurosensorial con la obtención de respuestas fallidas en las otoemisiones acústicas.

Estudio de seguimiento de las audiometrías de los años 2009, 2010 y 2011 de los pilotos de las fuerzas militares

La audición es el segundo mecanismo sensorial más importante después de la visión para obtener información durante la operación de una aeronave. Les permite a los pilotos percibir, procesar identificar los sonidos del ambiente que los rodea. Así necesita oír bien tanto en vuelo como en tierra, especialmente entre 500 y 3000 Hz para la recepción del lenguaje hablado y de las señales auditivas. Objetivo: Determinar los cambios progresivos en el tiempo y las frecuencias auditivas que se afectan en las audiometrías de los pilotos militares de las fuerzas militares en los años 2009, 2010 y 2011. Material y Métodos: Se trata de un estudio longitudinal de cohorte en el cual se identificará el comportamiento de las audiometrías de la población de pilotos de las fuerzas militares de Colombia en los años 2009, 2010 y 2011. Se hará una revisión retrospectiva de dichas audiometrías. Para dicho fin se tomó la población de pilotos de fuerzas militares que fueron distribuidos en grupos de pilotos de aeronave de ala fija que corresponden a 47 pilotos y ala rotatoria que son 155. Conclusiones: Se encontró que la frecuencia mas alterada en la población total fue la de 6000 Hz, que en lo pilotos de ala fija las frecuencias más afectadas fueron las de 4000 Hz y la de 6000Hz, la frecuencia más afectada en los pilotos de ala rotatoria fueron las de 4000 Hz, 6000 Hz y 8000 Hz, con lo que se concluye que la exposición en los pilotos afecta las frecuencias altas en las audiometrías. Se observó una relación con el número de horas de vuelo y las alteraciones audiométricas encontrándose una alteración en los pilotos entre 1000 y 4000 horas de vuelo en las frecuencias de 4000 Hz, 6000 Hz y 8000 Hz y una alteración de las todas las frecuencias en aquellos pilotos con más de 5000 horas de vuelo en el año 2009, presentando posterior recuperación en los años posteriores sin poder determinar en este estudio las causas de dicha recuperación. Los pilotos de ala rotatoria presentaron un incremento sostenido en todas las frecuencias en comparación con los pilotos de ala fija.

Developing a set of materials to teach hearing children about hearing impairment

This paper contains a set of materials to help hearing persons understand hearing loss.

A technique to train auditory and visual memory for speech patterns in young hearing-impaired children

This paper details a technique for training auditory memory for length of speech sounds in preschool children with a profound hearing loss.

Noise levels and hearing conservation in a water treatment facility

This paper describes a study assessing the sound levels and noise exposures of a municipal water treatment plant to determine the level of employee noise exposure dosages and to make any necessary recommendations regarding reducing the risk of noise induced hearing loss in employees.

Hearing hazards to firefighters

This paper examines the risks of occupational noise induced hearing loss in firefighters. OSHA and National Institute for Occupational Safety and Health (NIOSH) guidelines are described and noise data collected from the Blue Island (Illinois) Fire Department is analyzed.