La surdité est l'un des déficits sensoriels les plus fréquents dans nos sociétés industrialisées. Parmi les pathologies de l'audition, les surdités de perception ou neurosensorielles sont les plus répandues. Les surdités de perception sont dues à un dysfonctionnement de la cochlée impliquant l'homéostasie ionique, la perte des cellules sensorielles et des neurones ganglionnaires. Alors qu'une altération de l'homéostasie ou que la perte de cellules sensorielles entraine immanquablement la survenue d'une surdité, l'impact de la perte de neurones ganglionnaires est mal connu.L'objet de cette thèse était d'évaluer l'impact des pertes neuronales sur l'audition. Pour ce faire, nous avons développé un outil pharmacologique capable de créer une perte sélective de neurones auditifs primaires, sans endommager les structures pré-synaptiques telles que les cellules sensorielles et la strie vasculaire. Pour ce faire, nous avons appliqué des doses croissantes de ouabaïne sur la membrane de la fenêtre ronde chez la gerbille. Les tests électrophysiologiques (produits de distorsions acoustiques, potentiel endocochléaire et potentiel d'action composite du nerf auditif) ont été réalisés avant et 6 jours après l'application de ouabaïne. A la fin des explorations fonctionnelles, les cochlées étaient prélevées et préparées pour réaliser des évaluations morphologiques en microscopie confocale et en microscopie électronique à transmission.Jusqu'à 80 µM, la ouabaïne n'entrainait aucun changement significatif des produits de distorsions acoustiques ce qui reflétait le bon fonctionnement des cellules ciliées externes, ni du potentiel endocochléaire témoin du fonctionnement normal de la strie vasculaire. En revanche, les mêmes concentrations de ouabaïne provoquaient une diminution dose-dépendante de l'amplitude du potentiel d'action composite du nerf auditif, étroitement associée à une perte de neurones ganglionnaires et de synapses afférentes. Si l'amplitude du potentiel d'action composite du nerf auditif constitue un bon indicateur du nombre et de l'état fonctionnel des neurones ganglionnaires et des synapses afférentes, ce n'est donc pas le cas pour les seuils audiométriques. En effet, ce n'était qu'avec une perte de 75 % des synapses afférentes et supérieure à 55 % des neurones ganglionnaires, qu'une élévation des seuils audiométriques était observée, après une perfusion de 80 µM de ouabaïne. A 100 µM de ouabaïne, l'élévation des seuils auditifs résultait de la perte cumulée des cellules sensorielles et de l'altération de la strie vasculaire, se surajoutant aux dommages neuronaux et synaptiques.L'ensemble de nos résultats montrait que l'application de ouabaïne sur la membrane de la fenêtre ronde chez la gerbille constitue un excellent modèle pour étudier l'impact de la perte sélective des neurones ganglionnaires sur la fonction auditive. Il apparaît aussi nécessaire de développer des outils d'investigation plus précis que le simple audiogramme pour évaluer les pertes neuronales chez l'homme. / Deafness is one of the most frequent sensory deficits in our industrialized societies. Among the auditory pathologies, sensorineural deafness is the most wide-spread. Sensorineural deafness is due to a dysfunction of the cochlea involving the ionic homeostasis, loss of sensory cells and spiral ganglion neurons. While an alteration of the homeostasis or the loss of sensory cells induce inevitably the appearance of deafness, the impact of spiral ganglion neuron loss is unknown.The object of this thesis was to estimate the impact of spiral ganglion neuron losses on the auditory function. We developed a pharmacological tool capable of creating a selective loss of spiral ganglion neurons, without damaging the presynaptic structures such as the sensory cells and the stria vascularis. To do this, we applied increasing doses of ouabain to the round window membrane in the gerbil. Electrophysiological evaluations such as the distortion product otoacoustic emissions, the endocochlear potential and the compound action potentials of the cochlear nerve were recorded before and 6 days after application of ouabain. At the end of the functional evaluations, the cochlea were removed and prepared for morphological evaluations using confocal microscopy and transmission electron microscopy.Our results showed that up to a concentration of 80 µM, ouabain did not induce any significant change of the amplitude of the distortion product otoacoustic emissions, which indicated a normal functional state of the outer hair cells, nor of the endocochlear potential which reflected an intact stria vascularis. On the other hand, the same concentrations of ouabain led to a dose-dependent decrease of the amplitude of the compound action potentials, which was strictly associated with a loss of spiral ganglion neurons and afferent synapses, as assessed by morpho-anatomical analyses. If the amplitude of the compound action potentials constitutes a good indicator of the number and the functional state of the spiral ganglion neurons and the afferent synapses, it is not the case for the audiometric thresholds. Indeed, a loss of 75 % of afferent synapses and more than 55 % loss of the ganglion neurons was necessary before an elevation of the audiometric thresholds was observed in the cochleae perfused with 80 µM ouabain. At 100 µM ouabain, the elevation of the auditory thresholds may result from the accumulated loss of sensory cells, damage to the stria vascularis, in addition to the loss of the spiral ganglion neurons and afferent synapses. All these results indicate that the application of ouabain onto the round window membrane in the gerbil is an excellent model to study the impact of the selective loss of the spiral ganglion neurons on hearing function. More generally, this study points towards the necessity of developing more precise tools, beyond the simple audiogram, for the investigation of auditory neuron loss in humans.

In newborns, unconjugated bilirubin (UCB) is not readily excreted, and when bilirubin levels exceed the serum albumin binding capacity, pathological levels of UCB exist. Hyperbilirubinemia may lead to auditory damage and ultimately cause a hearing disorder called auditory neuropathy/dys-synchrony, characterized by absent or abnormal brainstem auditory evoked potentials (BAEPs) with evidence of normal inner ear function assessed by either otoacoustic emissions or cochlear microphonic responses. Phototherapy and double volume exchange transfusion are used as treatment methods for neonatal hyperbilirubinemia. Spontaneously jaundiced Gunn rat pups given sulfadimethoxine to displace bilirubin from serum albumin develop bilirubin encephalopathy and have abnormal BAEPs comparable to human neonates. BAEPs are a noninvasive electrophysiological measure of neural function of the auditory system. High levels of calcineurin activity are believed to be involved in the mechanism of this bilirubin induced auditory neuropathy. FK506, a calcineurin inhibitor, was administered 3 hours prior to sulfa in concentrations of 0.1mg/kg, 1.0mg/kg, and 10.0mg/kg body weight. Due to the observation that all animals had abnormal BAEPs after treatment with FK506 and sulfa, it can be concluded that none of the treatment doses protected against bilirubin induced auditory impairment.

A herança autossômica recessiva pode ser responsável por aproximadamente 77% dos casos de surdez hereditária. Em 1996, Chaib e col. mapearam o loco responsável por surdez profunda neurossensorial de herança recessiva na região cromossômica 2p22-23 (DFNB9). Em 1999, Yasunaga e col. identificaram esse gene como o que codifica a proteína OTOFerlina (OTOF) nessa região. Até hoje, já foram descritas 31 mutações patogênicas diferentes no gene OTOF em populações de várias origens, com destaque a mutação Q829X que foi encontrada em ~3% dos casos de surdez na Espanha (Migliosi e col., 2002; Rodríguez-Ballesteros e col., 2003). Alguns pacientes com mutações no gene OTOF apresentavam neuropatia auditiva, um tipo de deficiência auditiva neurossensorial caracterizada pela ausência ou anomalia das ondas no exame dos Potenciais Evocados Auditivos do Tronco Encefálico ou BERA com a presença das emissões otoacústicas e/ou microfonismo coclear. O objetivo desse projeto foi investigar a contribuição relativa das mutações no gene OTOF ao casos de neuropatia auditiva e de outros tipos surdez em famílias brasileiras. Uma amostra de 343 propósitos portadores de deficiência auditiva foi submetida ao estudo da mutação Q829X. Não foi identificada em nenhum caso. Dessa casuística foram selecionados 48 propósitos de famílias com consangüinidade ou com 2 ou mais afetados na irmandade e quatro pacientes com neuropatia auditiva e com consangüinidade parental ou com dois ou mais afetados na irmandade. Além disso, foram também selecionados 7 casos isolados com neuropatia auditiva e 5 casos de portadores de alterações no tronco encefálico. Essa amostra totalizou 64 propósitos. Propósitos dessas 64 famílias foram genotipados em relação a cinco marcadores de microssatélites ligados ao gene OTOF. A análise dos haplótipos excluiu ligação ao gene OTOF em 34 casos, 19 não eram conclusivos e 11 indicaram possibilidade de ligação ao gene OTOF (incluindo uma família com pais consangüíneos e neuropatia auditiva e três propósitos com neuropatia auditiva). Simultaneamente, os 64 propósitos foram triados para mutações em oito exons do gene OTOF, nos quais mutações já haviam sido descritas, por meio de SSCP seguido de seqüenciamento. Os 11 casos com resultados compatíveis com ligação ao gene OTOF (4 com neuropatia auditiva) e os sete casos de neuropatia auditiva foram selecionados para o seqüenciamento de todos os exons (total de 18 propósitos). Identificamos no total 58 alterações diferentes. Onze variantes eram potencialmentes patogênicas, encontradas em sete dos propósitos, todos pertencentes ao grupo dos 18 selecionados. Quatro casos eram heterozigotos compostos [98G>A (R33Q) e 2401G>T e 2402A>T (E801L)]; [1841G>A (G614E) e 3239G>C (R1080P)], [3751T>G (C1251G) e 5431A>T (K1811X)] e [2348delG (G783fs) e 5800-5801insC (L1934fs)], dois eram heterozigotos [1552-1567del16 (R518fs); 2905- 2923del19ins11 (A969fs)] sem que uma segunda mutação fosse detectada e um apresentava a mutação em homozigose [3400C>T (R1134X)]. Desses sete propósitos com mutações patogênicas, somente um paciente com mutação em heterozigose não apresentava neuropatia auditiva. Dentre os 11 casos com neuropatia auditiva, seis tinham pelo menos uma mutação no gene OTOF que poderia ser a causa de surdez. Esse achado reforça a associação entre o fenótipo da neuropatia auditiva e mutações no gene OTOF. A variante Q829X não foi encontrada nenhuma vez em nossa amostra, portanto, não deve ser causa importante de surdez na nossa população. Porém, nosso estudo mostra que mutações no gene OTOF são causas freqüentes de neuropatia auditiva no Brasil (mais de 50% dos casos). Nossos resultados reforçam a hipótese que pacientes com neuropatia auditiva devem ser selecionados para pesquisa de mutações no gene OTOF e que talvez mais de 50% dos casos de neuropatia auditiva tenham causa genética. / 77% of nonsyndromic prelingual deafness have an autosomal recessive inheritance. In 1996, Chaib et al. mapped a locus associated with sensorineural nonsyndromic recessive deafness to chromosome region 2p22-23 (DFNB9) by linkage studies. In 1999, Yasunaga et al. identified the OTOF gene encoding OTOFerlin, in this region. To date, there are 31 different pathogenic mutations described in the OTOF gene, from populations of variable origins. A Q829X mutation was found at a frequency of ~3% of deafness in Spain (Migliosi e col., 2002; Rodríguez-Ballesteros e col., 2003). Some affected individuals with mutations in the OTOF gene were reported to present auditory neuropathy, a type of deafness characterized by an absent or severely abnormal auditory brainstem response, with preservation of otoacoustic emissions and/or cochlear microphonics. The main purpose of this project was to investigate the relative contribution of OTOF mutations to auditory neuropathy and other type of deafness, amongst Brazilian families. We enrolled 343 Brazilian unrelated subjects with nonsyndromic hearing loss. A specific test for the Q829X mutation was performed first. We failed to find any subjects carrying this mutation. From this group, we selected 48 probands from families with consanguinity or with two or more affected sibs and four probands with diagnosis of auditory neuropathy and from consanguineous unions or with two or more affected sibs. In addition, we selected 7 isolated subjects with auditory neuropathy and 5 cases with diagnosis of brainstem alteration. This gave a total of 64 probands. Subjects from the 64 families were genotyped for five microsatellites markers, linked to the OTOF gene. The analysis of the haplotype excluded linkage to the OTOF gene in 34 families, it was inconclusive in 19 families and it showed compatibility with linkage in the remaining 11 families (including one with consanguineous parents and auditory neuropathy and three with diagnosis of auditory neuropathy). Simultaneously, the 64 subjects were screened for mutations in 8 exons previously identified to other mutations using the SSCP technique. In positive cases, DNA sequencing was carried out. In the 11 subjects consistent with putative linkage to OTOF gene and the 7 isolated cases of auditory neuropathy, an exon by exon screening for mutations in the OTOF gene was performed using DNA sequencing (Total of 18 subjects). We found a total of 58 different variants. Eleven were possibly causative mutations and were found in seven of the 18 subjects. Amongst them, four cases were compound heterozygotes R33Q with E801L, G614E with E1080P, 2348delG with 5800-5801insC and K1811X with C1251G, two cases were heterozygotes [1552- 1567del16 and 2905-2923del19in11] without a second mutation and one presented a mutation in homozygous form [3400C>T (R1134X)]. Among these seven probands, only one patient with a heterozygote mutation did not have a diagnosis of auditory neuropathy. In the 11 cases of auditory neuropathy, six had at least one mutation in the OTOF gene that is the probable cause of their deafness. These findings support the association between auditory neuropathy and mutations in the OTOF gene. While we failed to confirm the high frequency of Q829X mutation found in Spain, our study shows that mutations in the OTOF gene are frequent causes of auditory neuropathy in Brazil (more than 50%). Our results reinforced that patients with auditory neuropathy must be selected for mutation detection in the OTOF gene and that more than 50% of cases of auditory neuropathy have a defined genetic etiology.

A Desordem do Espectro da Neuropatia Auditiva (DENA) é uma alteração auditiva periférica com manifestações clínicas heterogêneas, o que pode tornar o processo de intervenção auditiva em crianças com essa patologia um desafio para os profissionais e para as famílias. Neste sentido, o objetivo deste estudo foi compreender a vivência de mães, no processo de intervenção auditiva de crianças com DENA. O estudo foi de natureza qualitativa e prospectiva. Como método investigativo foram realizadas entrevistas abertas, norteadas por uma pergunta disparadora, na busca por mais profundidade e reflexão sobre o fenômeno em questão. No total, treze mães foram entrevistas e, para compreensão dos relatos empreendeu-se uma análise de conteúdo de acordo com os referenciais teóricos de Bardin, que resultou nas seguintes categorias subcategorias: Manifestações emocionais durante o tratamento, com as subcategorias Sentimentos da mãe no processo de intervenção da deficiência auditiva, Expectativas durante o processo de tratamento, Atendimento interdisciplinar; Condutas terapêuticas e educacionais, com subcategorias Indicação e uso dos dispositivos eletrônicos, Condutas educacionais; Redes de apoio, com as subcategorias Grupos de Apoio, Aspectos da fé; Preconceito e Impactos da pesquisa para as participantes. O processo de intervenção auditiva de seus filhos com DENA inicialmente significou para as mães um mundo desconhecido, vivenciado por sentimentos de sofrimento e insegurança diante do diagnóstico. Conforme compreenderam melhor a DENA e observaram os resultados positivos das intervenções, puderam viver com mais tranquilidade. A esperança de um futuro melhor e o apoio recebido deram o sentido para continuarem sua trajetória. Esta pesquisa trouxe reflexões sobre o papel social dessas mães na relação DENA e família. Revelou também a importância da equipe interdisciplinar, das redes de apoio e do suporte psicológico. Aponta-se a necessidade de novos olhares paras as políticas públicas em saúde auditiva desde as redes básicas até os centros especializados de saúde. / The Auditory Neuropathy Spectrum Disorder (ANSD) consists in a specific type of hearing impairment with different etiologies and manifestation forms. Therefore, the process of auditory intervention in children with this pathology can be challenging for health professionals and families. Giving this circumstance, the objective of this study was to comprehend the experience of mothers focusing on the auditory intervention process of children with ANSD disorder. The research performed was qualitative and prospective. As an investigative method, open interviews were conducted, guided by a guiding question, in the search for more depth and reflection on the phenomenon in focus. In total thirteen mothers were interviewed and, in order to comprehend the narratives, a content analysis was performed based on Bardin theoretical references. The results were gathered in the following categories: Emotional manifestations during treatment, subcategories, Mother feelings during the auditory intervention process, Expectations during the treatment process, Interdisciplinary service; Therapeutic and educational conduct, subcategories Electronic device indication and usage, educational conduct, Support network, Support Groups, Faith aspects, Prejudice, and Research impact on participants. The process of auditory intervention of their children with ANSD initially meant for the mothers an unknown world, experienced by feelings of suffering and insecurity before the diagnosis. However, as they understood DENA better and the positive results of the intervention emerged, could live more peacefully. The hope for a better future and the support received has given the sense to continue their trajectories. This research brought reflections on the social role of these mothers in relation to ANSD and family. It also revealed the importance of the interdisciplinary team, the psychological and social support which mothers received, as well as the promotion of mothers\' health. It is pointed out the need for new public policies in hearing health from the basic to the specialized centers of health.

A herança autossômica recessiva pode ser responsável por aproximadamente 77% dos casos de surdez hereditária. Em 1996, Chaib e col. mapearam o loco responsável por surdez profunda neurossensorial de herança recessiva na região cromossômica 2p22-23 (DFNB9). Em 1999, Yasunaga e col. identificaram esse gene como o que codifica a proteína OTOFerlina (OTOF) nessa região. Até hoje, já foram descritas 31 mutações patogênicas diferentes no gene OTOF em populações de várias origens, com destaque a mutação Q829X que foi encontrada em ~3% dos casos de surdez na Espanha (Migliosi e col., 2002; Rodríguez-Ballesteros e col., 2003). Alguns pacientes com mutações no gene OTOF apresentavam neuropatia auditiva, um tipo de deficiência auditiva neurossensorial caracterizada pela ausência ou anomalia das ondas no exame dos Potenciais Evocados Auditivos do Tronco Encefálico ou BERA com a presença das emissões otoacústicas e/ou microfonismo coclear. O objetivo desse projeto foi investigar a contribuição relativa das mutações no gene OTOF ao casos de neuropatia auditiva e de outros tipos surdez em famílias brasileiras. Uma amostra de 343 propósitos portadores de deficiência auditiva foi submetida ao estudo da mutação Q829X. Não foi identificada em nenhum caso. Dessa casuística foram selecionados 48 propósitos de famílias com consangüinidade ou com 2 ou mais afetados na irmandade e quatro pacientes com neuropatia auditiva e com consangüinidade parental ou com dois ou mais afetados na irmandade. Além disso, foram também selecionados 7 casos isolados com neuropatia auditiva e 5 casos de portadores de alterações no tronco encefálico. Essa amostra totalizou 64 propósitos. Propósitos dessas 64 famílias foram genotipados em relação a cinco marcadores de microssatélites ligados ao gene OTOF. A análise dos haplótipos excluiu ligação ao gene OTOF em 34 casos, 19 não eram conclusivos e 11 indicaram possibilidade de ligação ao gene OTOF (incluindo uma família com pais consangüíneos e neuropatia auditiva e três propósitos com neuropatia auditiva). Simultaneamente, os 64 propósitos foram triados para mutações em oito exons do gene OTOF, nos quais mutações já haviam sido descritas, por meio de SSCP seguido de seqüenciamento. Os 11 casos com resultados compatíveis com ligação ao gene OTOF (4 com neuropatia auditiva) e os sete casos de neuropatia auditiva foram selecionados para o seqüenciamento de todos os exons (total de 18 propósitos). Identificamos no total 58 alterações diferentes. Onze variantes eram potencialmentes patogênicas, encontradas em sete dos propósitos, todos pertencentes ao grupo dos 18 selecionados. Quatro casos eram heterozigotos compostos [98G>A (R33Q) e 2401G>T e 2402A>T (E801L)]; [1841G>A (G614E) e 3239G>C (R1080P)], [3751T>G (C1251G) e 5431A>T (K1811X)] e [2348delG (G783fs) e 5800-5801insC (L1934fs)], dois eram heterozigotos [1552-1567del16 (R518fs); 2905- 2923del19ins11 (A969fs)] sem que uma segunda mutação fosse detectada e um apresentava a mutação em homozigose [3400C>T (R1134X)]. Desses sete propósitos com mutações patogênicas, somente um paciente com mutação em heterozigose não apresentava neuropatia auditiva. Dentre os 11 casos com neuropatia auditiva, seis tinham pelo menos uma mutação no gene OTOF que poderia ser a causa de surdez. Esse achado reforça a associação entre o fenótipo da neuropatia auditiva e mutações no gene OTOF. A variante Q829X não foi encontrada nenhuma vez em nossa amostra, portanto, não deve ser causa importante de surdez na nossa população. Porém, nosso estudo mostra que mutações no gene OTOF são causas freqüentes de neuropatia auditiva no Brasil (mais de 50% dos casos). Nossos resultados reforçam a hipótese que pacientes com neuropatia auditiva devem ser selecionados para pesquisa de mutações no gene OTOF e que talvez mais de 50% dos casos de neuropatia auditiva tenham causa genética. / 77% of nonsyndromic prelingual deafness have an autosomal recessive inheritance. In 1996, Chaib et al. mapped a locus associated with sensorineural nonsyndromic recessive deafness to chromosome region 2p22-23 (DFNB9) by linkage studies. In 1999, Yasunaga et al. identified the OTOF gene encoding OTOFerlin, in this region. To date, there are 31 different pathogenic mutations described in the OTOF gene, from populations of variable origins. A Q829X mutation was found at a frequency of ~3% of deafness in Spain (Migliosi e col., 2002; Rodríguez-Ballesteros e col., 2003). Some affected individuals with mutations in the OTOF gene were reported to present auditory neuropathy, a type of deafness characterized by an absent or severely abnormal auditory brainstem response, with preservation of otoacoustic emissions and/or cochlear microphonics. The main purpose of this project was to investigate the relative contribution of OTOF mutations to auditory neuropathy and other type of deafness, amongst Brazilian families. We enrolled 343 Brazilian unrelated subjects with nonsyndromic hearing loss. A specific test for the Q829X mutation was performed first. We failed to find any subjects carrying this mutation. From this group, we selected 48 probands from families with consanguinity or with two or more affected sibs and four probands with diagnosis of auditory neuropathy and from consanguineous unions or with two or more affected sibs. In addition, we selected 7 isolated subjects with auditory neuropathy and 5 cases with diagnosis of brainstem alteration. This gave a total of 64 probands. Subjects from the 64 families were genotyped for five microsatellites markers, linked to the OTOF gene. The analysis of the haplotype excluded linkage to the OTOF gene in 34 families, it was inconclusive in 19 families and it showed compatibility with linkage in the remaining 11 families (including one with consanguineous parents and auditory neuropathy and three with diagnosis of auditory neuropathy). Simultaneously, the 64 subjects were screened for mutations in 8 exons previously identified to other mutations using the SSCP technique. In positive cases, DNA sequencing was carried out. In the 11 subjects consistent with putative linkage to OTOF gene and the 7 isolated cases of auditory neuropathy, an exon by exon screening for mutations in the OTOF gene was performed using DNA sequencing (Total of 18 subjects). We found a total of 58 different variants. Eleven were possibly causative mutations and were found in seven of the 18 subjects. Amongst them, four cases were compound heterozygotes R33Q with E801L, G614E with E1080P, 2348delG with 5800-5801insC and K1811X with C1251G, two cases were heterozygotes [1552- 1567del16 and 2905-2923del19in11] without a second mutation and one presented a mutation in homozygous form [3400C>T (R1134X)]. Among these seven probands, only one patient with a heterozygote mutation did not have a diagnosis of auditory neuropathy. In the 11 cases of auditory neuropathy, six had at least one mutation in the OTOF gene that is the probable cause of their deafness. These findings support the association between auditory neuropathy and mutations in the OTOF gene. While we failed to confirm the high frequency of Q829X mutation found in Spain, our study shows that mutations in the OTOF gene are frequent causes of auditory neuropathy in Brazil (more than 50%). Our results reinforced that patients with auditory neuropathy must be selected for mutation detection in the OTOF gene and that more than 50% of cases of auditory neuropathy have a defined genetic etiology.

This research focused on the identification and description of predictors of pediatric and adult cochlear implantation outcomes in a South African cohort and the depiction of profound childhood hearing loss in terms of risk and intervention profiles. Study I described profound childhood hearing loss in a South African cohort of pediatric cochlear implant (CI) recipients in terms of risk profile and age of diagnosis and intervention. A retrospective review of patient files for 264 pediatric CI recipients from five CI programs was conducted. For all subjects, permanent congenital and early onset hearing loss (PCEHL) was confirmed under the age of five years old. The most prevalent risks for profound PCEHL were neonatal intesive care unit (NICU) admittance (28.1%), family history of childhood hearing loss (19.6%) and prematurity (15.1%). An associated syndrome was diagnosed in 10% of children and 23.5% had at least one additional developmental condition. Hearing loss for most (77.6%) children was confirmed as congenital or early onset, while 20.3% presented with postnatal onset of hearing loss. Auditory Neuropathy Spectrum Disorder (ANSD) was diagnosed in 5% of children, with admittance to NICU (80%) and hyperbilirubinemia (50%) being the most prevalent risk factors for these cases. Hearing loss was typically diagnosed late (15.3 months), resulting in delayed initial hearing aid fitting (18.8 months), enrollment in early intervention services (19.5 months), and eventual cochlear implantation (43.6 months). Delayed diagnosis and intervention predispose this population to poorer outcomes. / Thesis (DPhil)--University of Pretoria, 2016. / Speech-Language Pathology and Audiology / DPhil / Unrestricted

Acromegalia à uma doenÃa endÃcrina rara. Poucos estudos avaliaram sua associaÃÃo com deficiÃncia auditiva (DA) ou distÃrbios de conduÃÃo do impulso neural auditivo.Osresultados sÃo conflitantes. O objetivo à avaliar a transmissÃo auditiva central e perifÃrica em pacientes com acromegalia. AlÃm disso, avaliar a prevalÃncia e caracterÃsticas da DA em pacientes com acromegalia. Foi feito um estudo transversal com 36 pacientes com acromegalia de um ambulatÃrio especializado em Fortaleza-CearÃ. Foram excluÃdos pacientes com otoscopia anormal ou com histÃria familiar de deficiÃncia auditiva, uso de ototÃxicos ou exposiÃÃo a ruÃdo ocupacional. Inicialmente, o grupo foi avaliado por meio de audiometria tonal limiar. Considerou-se deficiÃncia auditiva (DA) quando a mÃdia dos tons puros foi > 25DbNA para baixas freqÃÃncias (250, 500, 1000 e 2000 Hz) ou altas freqÃÃncias (3000, 4000, 6000 e 8000 Hz).O grupo foi dividido em: acromegalia com DA (Acro DA) e sem DA (Acro NDA) e comparados quanto aos nÃveis hormonais e parÃmetros metabÃlicos. Posteriormente, este grupo de pacientes com acromegalia foi dividido em 2 subgrupos: com (n=16) e sem (n=20) diabetes ou intolerÃncia à glicose de jejum (DM/IGJ). Os resultados foram comparados entre os subgrupos e grupo controle (n=20) quantos aos parÃmetros dos potenciais evocados auditivos de tronco encefÃlico (PEATE). Para avaliar a normalidade da distribuiÃÃo foi utilizado o teste de Kolmogorov-Smirnov quando necessÃrio. Utilizou-se os testes qui-quadrado, t de Student e coeficiente de correlaÃÃo de Pearson. O nÃvel de significÃncia estatÃstica escolhido foi p<0.05 (statistical package for social sciences-SPSS 12.0). Dos 36 pacientes estudados, 14 (38,9%) mostraram DA sensorioneural (Acro DA), sendo em 9 casos bilateral e 5 unilateral. Nenhum apresentou DA mista ou condutiva. A prevalÃncia de DM/IGJ foi similar entre os grupos. As frequÃncias de 250, 3000, 4000, 6000 e 8000 Hz foram as mais afetadas e com padrÃo similar em ambos os lados.O grupo com acromegalia apresentou latÃncia da onda I em orelha direita aumentada em comparaÃÃo ao grupo controle (p=0,007), sem diferenÃa quanto aos intervalos interpicos em nenhum dos lados. Esse padrÃo foi o mesmo quando se comparou o subgrupo com DM/IGJ com o controle.TambÃm houve aumento da latÃncia da onda I na orelha direita em relaÃÃo à orelha esquerda no grupo com acromegalia. Em conclusÃo, mostrou-se uma elevada prevalÃncia de DA sensorioneural em pacientes com acromegalia.No entanto, nÃo se observou relaÃÃo dessa deficiÃncia com caracterÃsticas clÃnicas e metabÃlicas da doenÃa.Pacientes com acromegalia associada DM/IGJ mostraram um retardo no impulso neural no nervo auditivo unilateralmente à direita, evidenciando um efeito neuropÃtico nÃo homogÃneo dos distÃrbios do metabolismo dos carboidratos sobre o nervo auditivo. / Acromegaly is a rare endocrine disease. Few studies have evaluated its association with hearing loss (HL) or disturbance in conduction of the auditory neural impulse. The results are conflicting. The aim is to evaluate central and peripheral auditory transmission in acromegalic patients. Besides, to evaluate the prevalence and characteristics of HL in patients with acromegaly. A cross-sectional study was carried out on 36 patients with acromegaly in a specialized ambulatory in Fortaleza-CearÃ. Patients with abnormal otoscopy, family history of hearing loss, use of ototoxic drugs or occupational noise exposure were excluded. Initially, the group was evaluated by pure tone audiometry. HL was considered when pure tone average was > 25 DBHL for low frequencies (250, 500, 1000 e 2000 Hz) or high frequencies (3000, 4000, 6000 e 8000 Hz). The whole group was divided in: acromegaly with HL (Acro HL) and without HL (AcroNHL) and compared in regards to hormonal levels and metabolic parameters. Additionally that group of patients with acromegaly was divided into 2 subgroups: with (n=16) and without (n=20) diabetes mellitus/impaired glucose tolerance (DM/IGT). The results were compared among these subgroups and a control group (n=20) regarding the brainstem auditory evoked potentials (BAEP) parameters.Kolmogorov-Smirnov test was used to evaluate the normality of distribution when necessary. Qui-quadrado, Student t test and Pearson correlation coefficient were carried out. The level of statistical significance chosen was at p<0.05 (statistical package for social sciences-SPSS 12.0). Among 36 patients evaluated, 14 (38,9%) showed sensorioneural HL (Acro HL), being 9 bilateral and 5 unilateral cases. No one had mixed or conductive HL. The prevalence of diabetes/impaired glucose tolerance was similar between the groups. The frequencies 250, 3000, 4000, 6000 and 8000 Hz were the most affected and with a similar pattern in both ears. The group with acromegaly showed a prolonged peak I latency in the right ear in comparison to the control group (p=0,007), with no difference regarding the interpeak intervals in any sides. This pattern was the same when comparing the DM/IGT subgroup to controls. Also, we found a prolonged peak I latency in the right ear in relation to the left ear in the group with acromegaly.In conclusion, a high prevalence of sensorineural HL was shown in patients with acromegaly. Nevertheless, no correlation was observed between this dysfunction and clinical or metabolic characteristics of the disease. Patients with acromegaly associated with DM/IGT showed a delayed neural impulse in the auditory nerve unilaterally in the right side, evidencing a non-homogenous neuropathic effect of the carbohydrate metabolism disturbances on the auditory nerve.

No description available.

Les neuropathies optiques héréditaires se caractérisent par une dégénérescence des cellules ganglionnaires de la rétine entraînant une perte visuelle modérée voire la cécité. L'atrophie optique dominante (AOD) ou maladie de Kjer et la neuropathie optique de Leber (NOHL), sont les deux formes les plus fréquentes. Il existe quatre loci d'AOD mais seulement deux gènes identifiés : OPA1 et OPA3 codant des protéines mitochondriales. La NOHL est due à des mutations de l'ADN mitochondrial (ADNmt). Aucun traitement n'existe pour soigner ces pathologies ou ralentir leur progression. Nous nous sommes intéressés au gène YWHAH, situé au locus OPA5, codant la protéine 14-3-3eta, un des gènes majoritairement exprimés dans les GCRs. Le criblage de YWHAH dans des banques d'ADNs de patients exempts de mutation dans OPA1, OPA3 et l'ADNmt a permis d'identifier deux mutations hétérozygotes chez des patients présentant une AOD et une surdité profonde.14-3-3eta joue un rôle de protection dans l'apoptose. En effet, les fibroblastes de patients et des cellules surexprimant une 14-3-3eta mutée s'avèrent moins résistants à un stress apoptotique. Pour évaluer l'effet des mutations de 14-3-3eta sur la fonction visuelle et auditive nous avons généré une souris reproduisant une mutation humaine. Les souris 14-3-3eta hétéro et homozygotes ont une atteinte auditive de 15 à 20 décibels dès 2 mois, et seules les souris homozygotes présentent une altération de la fonction visuelle à partir de 12 mois affectant les interneurones et les photorécepteurs de la rétine. La souris mutante présente un phénotype moins grave que chez l'homme, mais son étude permet d'impliquer 14-3-3eta dans des atteintes neurosensorielles / Inherited Optic Neuropathies (ION) are characterized by the degeneration of the Retinal Ganglion Cells (RGCs), leading to moderate visual loss or legal blindness. Dominant Optic Atrophy or Kjer disease (DOA) and Leber Hereditary Optic Neuropathy (LHON) are the most common forms of IONs. There are four loci for DOA, but only two genes have been identified: OPA1 and OPA3 encoding mitochondrial proteins. LHON is caused by mitochondrial DNA (mtDNA) mutations. There is no treatment to cure these diseases or slow down their progression. In order to identify new genes responsible for DOA, our team was interested in the YWHAH gene localized at the OPA5 locus, coding the 14-3-3eta protein, a gene strongly expressed in RGCs. The screening of YWHAH in DNAs without mutation in OPA1, OPA3 and mtDNA allowed us to identify two heterozygous mutations in patients presenting a DOA associated to a severe deafness.As 14-3-3eta plays a role in apoptosis, we studied patient fibroblasts and found that they present a marked susceptibility to apoptosis. Moreover, the mutated alleles of 14-3-3eta lost their ability to confer resistance to cell death. In order to evaluate the effects of the 14-3-3eta mutations on the visual and auditory functions, we have generated an animal model mimicking a human mutation. The 14-3-3eta hetero and homozygous mice present a stable auditory impairment of 15 to 20 decibels, whereas only the homozygous mice present an alteration of the visual function at 12 months, with affected interneurones and photoreceptors. Even if the mutant mouse does not present a phenotype as dramatic as in human, its study shed light on 14-3-3eta involvement in neuronsensorial functions

Introdução: A presença de perdas auditivas de origem neural no adulto que já desenvolveu linguagem pode acarretar alteração de compreensão da fala com dificuldade na discriminação auditiva dos sons e entendimento completo da mensagem. Entre as causas de perdas auditivas neurais está o distúrbio do espectro da neuropatia auditiva (DENA). A maioria das publicações sobre o DENA descrevem o padrão do diagnóstico auditivo, entretanto as consequências dessa alteração auditiva para a comunicação do indivíduo e as implicações dessas para o tratamento fonoaudiólogico são escassas. Faz-se necessária a identificação das especificidades linguísticas a serem avaliadas nos neuropatas, por meio de um protocolo de avaliação direcionado, para permitir a elaboração de diretrizes terapêuticas bem delineadas. Objetivo: Este estudo teve como objetivo descrever as manifestações linguísticas em adultos com o Distúrbio do espectro da neuropatia auditiva (DENA). Métodos: Foram incluídos neste estudo pacientes adultos identificados com o diagnóstico de DENA, alfabetizados, sem alterações neurológicas e cognitivas, no período entre 2007 e 2009 no setor de Fonoaudiologia do Ambulatório de Otorrinolaringologia do HCFMUSP. Doze pacientes foram selecionados, sendo 8 do sexo masculino (66,7%), com idades entre 18 e 50 anos. Foi elaborado um protocolo de anamnese incluindo dados sobre escolaridade, uso de amplificação sonora individual (AASI) e queixas auditivas específicas. O protocolo de avaliação constou de provas que abordaram a avaliação da recepção auditiva e da emissão de fala (identificação fonêmica; inteligibilidade; leitura e compreensão de texto e consciência fonológica) e da expressão (fala e elaboração). Os estímulos foram dados por via somente auditiva e no modo auditivo e visual (com leitura orofacial - LOF). Resultados: As principais características observadas nestes pacientes: sexo masculino, ensino fundamental incompleto, uso de AASI menor que três meses em ambas as orelhas, dificuldade de ouvir em ambientes ruidosos e diálogo foram as situações comunicativas que geraram maior dificuldade na expressão. Observou-se que em todas as provas com apoio da LOF, houve melhora significativa da percepção da fala do ponto de vista clínico. Conclusões: As especificidades linguísticas dos pacientes adultos com DENA encontradas foram: baixa escolaridade, velocidade de fala alterada, dificuldade de compreensão de texto tanto pela via auditiva como pela leitura, dificuldade de consciência fonológica, melhora da repetição de palavras e frases com o uso da LOF. / Introduction: Post linguistic neural hearing loss in adults can lead to speech alterations and difficulties in auditory discrimination of sounds and comprehension of the message. Auditory neuropathy spectrum disorder (ANSD) is among the causes of neural hearing loss. Most studies on ANSD describe the standard for auditory diagnosis. However, the consequences of such hearing impairment in communication and its implication on speech therapy are scarce. Thus, it is necessary to identify the specific language aspects to be assessed in neurologically impaired individuals through a directed assessment protocol to allow the development of outlined treatment guidelines. Objective: This study aimed to describe the linguistic manifestations in adults with ANSD. Methods: The study included adults diagnosed with ANSD, who were literate and had no neurological or cognitive alterations. Data collection was carried out between 2007 and 2009 at the Speech, Language and Hearing service of the Clinic of Otorhinolaryngology of HCFMUSP. Twelve patients, eight males (66,7%) with ages ranging from 18 and 50 years of age were selected. An anamnesis protocol was designed. This protocol included data on education, use of hearing aids (HA) and specific hearing complaints. The assessment protocol consisted on tests of auditory reception and production of speech (phonemic identification; intelligibility; reading and text comprehension; and phonological awareness) and expression (speech and elaboration). The stimuli input were given in auditory only and in auditory plus visual mode (with lip reading). Results: The main characteristics observed in all participants were: male gender; incomplete primary school; use of hearing aids for less than three months in both ears; difficulty hearing in noisy environments; and dialogue, were the communicative situations that led to greater difficulty in expression. A significant improvement in speech perception was observed in all tests with lip reading. Conclusions: The language specificities of individuals with ANSD were: low educational level; speech rate alterations; difficulty in reading comprehension both by hearing and by reading; difficulty in phonological awareness; improvement of words and phrases repetition using LR.