Hipoacusia sensorioneural unilateral: Revisión de los manejos posibles en nuestra realidad nacional / Unilateral sensorineural hearing loss: Review of possible management in our national reality

La hipoacusia unilateral (HUL) definida como la pérdida auditiva de cualquier grado en un solo oído tiene prevalencias en edad escolar de 3% a 6%. La etiología es desconocida en la mayoría de los casos, pero destacan las anormalidades anatómicas severas a diferencia de las hipoacusias bilaterales, lo que le otorga importancia al estudio de imágenes. También se recomienda realizar evaluación oftalmológica. El impacto de la HUL se observa en la localización sonora, reconocimiento del habla, desarrollo del lenguaje, desempeño social y conducta, pero por sobre todo en el rendimiento académico. En este sentido es relevante mencionar que además de existir mayor probabilidad de repitencia de curso, es necesario mayor apoyo educacional individualizado para evitar dicha repitencia o lograr mismo éxito académico que un normoyente. En relación al diagnóstico aún faltan normas o protocolos, siendo éste un desafío en las zonas donde no hay screening universal. Se discute la importancia de las encuestas para realizar evaluaciones y seguimiento en estos casos. Finalmente se abordan las estrategias de intervención disponibles, además de un plan individualizado considerando al niño, su familia y sus expectativas, particularmente se discuten las características o factores a tomar en cuenta en el momento de la adaptación, para así lograr un tratamiento tendiente al éxito.

Unilateral hearing loss (UHL) defined as hearing loss of any degree in only one ear has a school-age prevalence of 3% to 6%. The etiology is unknown in most cases, but severe anatomical abnormalities stand out as opposed to bilateral hearing loss, which gives importance to the study of images. Ophthalmological evaluation is also recommended. The impact of UHL is observed in sound localization, speech recognition, language development, social performance and behavior, but above all in academic performance. In this sense, it is relevant to mention that in addition to having a higher probability of repeating the course, it is necessary to have more individualized educational support to avoid this repetition or achieve the same academic success as a normal listener. Regarding the diagnosis, there are still missing norms or protocols, this being a challenge in areas where there is no universal screening. The importance of surveys to carry out evaluations and follow-up in these cases is discussed. Finally, the available intervention strategies are discussed, in addition to an individualized plan considering the child, his family and his expectations, particularly, the factors to be taken into account at the time of adaptation, in order to achieve a success treatment.

Hipoacusia unilateral: bases neurobiológicas de la ambliaudia / Unilateral hearing loss: neurobiological basis of amblyaudia

Resumen La hipoacusia unilateral es una alteración prevalente e importante en la población infantil que puede llevar a un deterioro del procesamiento auditivo. Cualquier patología que cause hipoacusia asimétrica (conductiva o sensorioneural) durante ventanas críticas del desarrollo cerebral, puede dar lugar a déficits del procesamiento auditivo que podrían persistir incluso después de la rehabilitación audiológica. Este proceso fisiopatológico se ha denominado "ambliaudia" y los niños que la presentan tienen un mayor riesgo de sufrir retraso en el desarrollo del lenguaje, así como de padecer dificultades académicas, sociales y cognitivas. Por esto, la ambliaudia se presenta como un desafío en audiología, siendo necesario comprender los mecanismos neurobiológicos que la subyacen. Entender de mejor manera cuáles son las consecuencias que tiene la pérdida auditiva asimétrica sobre el desarrollo del sistema nervioso podría ser clave para guiar de mejor forma las intervenciones terapéuticas. En este artículo se revisan trabajos en humanos y en modelos animales que describen las consecuencias neurobiológicas de la deprivación auditiva unilateral durante el desarrollo del sistema nervioso y su posible aplicación a la práctica clínica.

Abstract Unilateral hearing loss is a prevalent and important disorder in children that can lead to an impairment of auditory processing. Any pathology that causes asymmetric (conductive or sensorineural) hearing loss during critical brain development windows can lead to hearing deficits that may persist even after audiological rehabilitation. This pathophysiological process has been referred to as amblyaudia, and children are at greater risk of experiencing language developmental delays as well as academic, social and cognitive impairments. For this reason, amblyaudia presents itself as a challenge in audiology, and it has become necessary to understand its neurobiological mechanisms. A better understanding of the consequences of asymmetric hearing loss on the development of the nervous system may be key to better guiding therapeutic interventions. This article reviews studies performed in humans and animal models that describe the neurobiological consequences of unilateral hearing deprivation during the development of the nervous system and its possible applications to clinical practice.

Auditory processing disorders in incarcerated youth: A call for early detection and treatment.

BACKGROUND: Numerous reports have linked language impairment, academic underachievement, and attention disorder to misbehavior in adolescence. Recent studies have found an association between deficits in hearing and auditory processing and involvement in the juvenile justice system. In fact, the existence of an auditory processing disorder (APD) is a risk factor for adolescent delinquency even in the presence of normal hearing. The nexus between APD, low academic achievement and offending behavior in teens has prompted recommendation for early screening of school children for abnormalities in auditory processing. Using a variety of diagnostic tools, investigators have found an increase in the frequency of APD in cohorts of confined youthful offenders. The present investigation evaluates the prevalence of APD in a group of incarcerated youth residing in a detention center. METHODS: A total of 52 incarcerated adolescents (8 females and 44 males; age range 13-20 (M = 16.0), residing at a juvenile detention center in Pittsburgh, Pennsylvania and determined to have normal auditory acuity were included in the study. All participants were screened for APD using two dichotic listening tests, the Randomized Dichotic Digits Test (RDDT) and the Dichotic Words Test (DWT), evaluative modalities to identify deficits in auditory processing. The prevalence of APD in the study group was compared to previously published normative data for non-offending age-matched youth. RESULTS: On the RDDT, 23.1% of participants demonstrated normal auditory processing, while 77% had abnormal test results. On the DWT, 75% of subjects exhibited normal auditory processing, while the scores were abnormal for 24.9%. When the results of the RDDT and the DWT were combined to establish a pattern for the purpose of interpreting a deficit, 21.1% of the participants produced results that were within normal limits, while 17.3% qualified for a diagnosis of APD, with abnormal results on both tests. Previous studies have estimated the prevalence of auditory processing disorder in the general adolescent population as being between 2% and 7%. CONCLUSIONS: This study found a higher prevalence of auditory processing disorder in a cohort of incarcerated youth compared with age-matched controls. Diagnostic screening protocols that identify at-risk children have been developed, as have effective therapies to improve auditory processing function. Teachers, pediatricians and psychologists should consider APD in children and adolescents with behaviors that may increase their risk for juvenile justice involvement. Studies on optimal timing and strategies for assessing and treating APD in children and adolescents are needed, including youth caught up in the juvenile justice system.

Evidence of binaural integration benefits following ARIA training for children and adolescents diagnosed with amblyaudia.

OBJECTIVE: The purpose of this study was to demonstrate the efficacy of Auditory Rehabilitation for Interaural Asymmetry (ARIA) to improve dichotic listening scores in children and adolescents diagnosed with amblyaudia and other binaural integration deficits. DESIGN: The study is a field experiment without randomisation. STUDY: Participants placed into groups based on dichotic listening test scores received four sessions of ARIA training. Baseline scores were compared to performance during the final session of training and to scores obtained 2 or more months after completion of ARIA. SAMPLE: A total of 125 children participated at five different clinical sites. RESULTS: Dichotic listening scores improved across all participants. Post hoc analyses demonstrated highly significant gains in non-dominant ear performance and reductions of interaural asymmetry among participants diagnosed with amblyaudia at both post-ARIA measurements. Participants in other diagnostic groups also showed significant benefits for some post-ARIA measures. CONCLUSIONS: Results demonstrate that ARIA training is an effective method for improving binaural integration skills among children and adolescents identified with dichotic listening weaknesses during assessments for auditory processing disorder (APD), especially for those diagnosed with amblyaudia. Benefits achieved following ARIA training remain stable across several months.

The Necessity of Amblyopia.

A general property of nervous system development is that correlated activity is used to organize topographic projections. This correlated activity is typically produced by electrical coupling of adjacent neurons; however, electrical coupling is not possible for retinal ganglion cells in separate eyes that need to be precisely mapped to the same place in the brain. This forces the visual system to rely on environmental stimuli to produce the correlated activity that drives the development of binocularity, with amblyopia as necessary consequence when visual experience is abnormal. The characteristic visual deficits in both the amblyopic and the sound eyes can be understood in the context of these normal developmental processes. The auditory system provides another example-where precise connections between paired sense organs must rely on environmental stimuli for normal development-in which the analogous condition of amblyaudia occurs.

Amblyaudia: Review of Pathophysiology, Clinical Presentation, and Treatment of a New Diagnosis.

OBJECTIVE: Similar to amblyopia in the visual system, "amblyaudia" is a term used to describe persistent hearing difficulty experienced by individuals with a history of asymmetric hearing loss (AHL) during a critical window of brain development. Few clinical reports have described this phenomenon and its consequent effects on central auditory processing. We aim to (1) define the concept of amblyaudia and (2) review contemporary research on its pathophysiology and emerging clinical relevance. DATA SOURCES: PubMed, Embase, and Cochrane databases. REVIEW METHODS: A systematic literature search was performed with combinations of search terms: "amblyaudia," "conductive hearing loss," "sensorineural hearing loss," "asymmetric," "pediatric," "auditory deprivation," and "auditory development." Relevant articles were considered for inclusion, including basic and clinical studies, case series, and major reviews. CONCLUSIONS: During critical periods of infant brain development, imbalanced auditory input associated with AHL may lead to abnormalities in binaural processing. Patients with amblyaudia can demonstrate long-term deficits in auditory perception even with correction or resolution of AHL. The greatest impact is in sound localization and hearing in noisy environments, both of which rely on bilateral auditory cues. Diagnosis and quantification of amblyaudia remain controversial and poorly defined. Prevention of amblyaudia may be possible through early identification and timely management of reversible causes of AHL. IMPLICATIONS FOR PRACTICE: Otolaryngologists, audiologists, and pediatricians should be aware of emerging data supporting amblyaudia as a diagnostic entity and be cognizant of the potential for lasting consequences of AHL. Prevention of long-term auditory deficits may be possible through rapid identification and correction.