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MAIN AIM: To electrophysiologically determine the impact of moderate to severe chronic hypoxia (H) resulting from a wide array of CHD (HCHD) conditions on the integrity of brainstem function. MATERIALS AND METHODS: Applying brainstem auditory-evoked response methodology, 30 chronically afflicted HCHD patients, who already had undergone heart surgery, were compared to 28 healthy control children (1-15 yo) matched by age, gender and socioeconomic condition. Blood oxygen saturation was clinically determined and again immediately before brainstem auditory-evoked response testing. RESULTS: Among HCHD children, auditory wave latencies (I, III and V) were significantly longer (medians: I, 2.02 ms; III, 4.12 ms, and; V, 6.30 ms) compared to control (medians: I, 1.67ms; III, 3.72 ms, and; V, 5.65 ms), as well as interpeak intervals (HCHD medians: I-V, 4.25 ms, and; III-V, 2.25ms; control medians: I-V, 3.90 ms and, III-V, 1.80 ms) without significant differences in wave amplitudes between groups. A statistically significant and inverse correlation between average blood oxygen saturation of each group (control, 94%; HCHD, 78%) and their respective wave latencies and interpeak intervals was found. CONCLUSIONS: As determined by brainstem auditory-evoked responses, young HCHD patients manifestly show severely altered neuronal conductivity in the auditory pathway strongly correlated with their hypoxic condition. These observations are strongly supported by different brainstem neurological and image studies showing that alterations, either in microstructure or function, result from the condition of chronic hypoxia in CHD. The non-altered wave amplitudes are indicative of relatively well-preserved neuronal relay nuclei.

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Resumen Introducción: el tamizaje auditivo es un método de detección y su propósito es intervenir de forma temprana para reducir las consecuencias negativas de una eventual afección auditiva en el desarrollo integral del infante. Costa Rica ha implementado en el sistema de salud público un programa de tamizaje auditivo neonatal universal, donde se examina todo niño o niña antes del primer mes de vida. Aunque se han percibido múltiples beneficios, es importante demostrar con evidencia científica si cumple sus objetivos. Metodología: se analizó la eficacia del «Programa de tamizaje auditivo neonatal universal» (TANU) de la Caja Costarricense de Seguro Social, a partir de la información registrada de 37 656 infantes evaluados entre los años 2016 y 2018, mediante el contraste empírico con las técnicas descriptivas de distribución de frecuencias de variables, y las pruebas inferenciales chi cuadrado y análisis de varianza (ANOVA). Resultados: en cuanto a la edad al momento del examen, el 71 % de la muestra tenía entre 0 y 3 días. Su desempeño a través del tiempo y la extensión a distintos centros de salud ha sido satisfactorio, así mismo, la cantidad de infantes valorados ha sido hasta del 98 % de la población. Conclusiones: el programa TANU es eficaz en la mayoría de aspectos analizados, destaca la identificación de factores de riesgo y la detección temprana de afecciones auditivas, sin embargo, se proponen mejoras en relación con el manejo de la información.

Abstract Introduction: Hearing screening is a detection method, its objective is to provide an early intervention that allows reducing the negative consequences of an eventual hearing impairment, in the integral development of the infant. Costa Rica has implemented a universal neonatal hearing screening program in the public health system, where the hearing of every child born in the country is examined before the first month of life. Although multiple benefits have been perceived, it is important to demonstrate with scientific evidence if it accomplishes its objectives. Methodology: the effectiveness of the Universal Newborn Hearing Screening Program in Costa Rica was analyzed, based on the information recorded from 37,656 children evaluated since 2016 to 2018, through empirical contrast using both descriptive techniques: frequency distribution of variables, as well as the use of inferential tests: chi square and analysis of variance (ANOVA). Results: 71 % of the sample was between 0 and 3 days old at the moment of being examined. Its performance over time and extension to different health centers has been satisfactory, likewise, the number of infants evaluated has been up to 98 % of the population. Conclusions: the TANU program is effective in most of the aspects analyzed, the identification of risk factors and the early detection of hearing disorders are outstanding, however, improvements are proposed in relation to the handling of information.

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Introducción: El potencial evocado visual es una técnica que permite la evaluación de la integridad funcional de la vía visual; su aplicación en niños pequeños resulta de gran dificultad. Objetivo: Caracterizar desde el punto de vista fisiológico el potencial evocado visual en niños menores de 5 años. Métodos: Estudio descriptivo transversal, donde se registran respuestas visuales obtenidas con diodos (montados en gafas) en 112 niños sanos (65 varones, 47 hembras) con rango de edad entre 3 meses y 5 años. Se calcularon los valores medios y desviación estándar de latencias y amplitudes de cada componente de la respuesta y se estimaron sus dinámicas madurativas en función de la edad. Se utilizó un análisis de componentes principales para explicar la variabilidad morfológica (complejo N1-P1-N2) y, se calculó una ecuación discriminante (con indicadores de replicación y relación señal/ruido), para evaluar la contribución en su mejor detección. Resultados: La morfología típica encontrada resultó consistente, replicable y mostró un nivel de detección visual > 90 por ciento (para cada componente), con 85 por ciento de acierto global (clasificaciones correctas) mediante la ecuación discriminante. El complejo N1-P1-N2, consigue explicar > 70 por ciento de la varianza de esta respuesta. Se demostró un acortamiento significativo de latencia con la edad (regresión, p≤ 0,05) para los componentes N1, P1 (marginal, N2). Los valores de amplitud resultaron de mayor dispersión y su tendencia al incremento no alcanzó significación. Conclusiones: El registro del potencial evocado visual mediante diodos/gafas demuestra la obtención de respuestas fisiológicas consistentes y replicables (alta detectabilidad) con una variabilidad morfológica controlable(AU)

Introduction: The Visual Evoked Potentials is a neurophysiological technique to provide an objective assessment of the functional integrity of the visual pathway. However, the young children population is a particularly difficult (uncooperative) group to obtain visual responses. Objective: The purpose of this study was to describe electrophysiological characteristics of the visual response in children. Methods: Descriptive, cross-sectional study. Transient visual evoked potentials with goggles were recorded from 112 healthy children (65 males, 47 females) aged between 3 months to 5 years old. The mean (and standard deviations) for latencies and amplitudes of each component was calculated and both statistical significance in function of age was analyzed (linear regression model). Principal component analysis is use to explain the visual waveform variability. A discriminant equation (with indicators of reliability and noise/signal ratio) is calculate to evaluate contribution in detectability. Results: The typical waveform of (N1, P1, N2, components) is consistent and reliable and showed a visual detection level >90 percent (for each component) and 85 percent of global success (good classifications) with the discriminant equation. N1-P1-N2 complex is able to explain >70 percent of the visual response variance. A significant reduction of N1, P1 (N2, marginal) latencies with increasing age is demonstrated (linear regression, p≤0.05). There was no significant difference for age-dependent increased pattern of amplitude data (high variability). Conclusions: The visual evoked potentials/goggles obtained in infants and young children are consistent and reliable physiological responses (high detectability) with recognizable morphological variability(AU)

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Objective response detection (ORD) techniques such as the magnitude-squared coherence (MSC) are mathematical methods tailored to detect potentials evoked by an external periodic stimulation. The performance of the MSC is directly proportional to the signal-to-noise ratio (SNR) of the recorded signal and the time spent for collecting data. An alternative to increasing the performance of detection techniques without increasing data recording time is to use the information from more than one signal simultaneously. In this context, this work proposes two new detection techniques based on the average and on the product of MSCs of two different signals. The critical values and detection probabilities were obtained theoretically and using a Monte Carlo simulation. The performances of the new detectors were evaluated using synthetic data and electroencephalogram (EEG) signals during photo and auditory stimulation. For the synthetic signals, the two proposed detectors exhibited a higher detection rate when compared to the rate of the traditional MSC technique. When applied to EEG signals, these detectors resulted in an increase of the mean detection rate in relation to MSC for visual and auditory stimulation of at least 25% and 13.21%, respectively. The proposed detectors may be considered as promising tools for clinical applications. Graphical Abstract.

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Auditory and visual pathways may be affected as a consequence of temporal lobe epilepsy surgery because of their anatomical relationships with this structure. The purpose of this paper is to correlate the results of the auditory and visual evoked responses with the parameters of tractography of the visual pathway, and with the state of connectivity between respective thalamic nuclei and primary cortices in both systems after the surgical resection of the epileptogenic zone in drug-resistant epileptic patients. Tractography of visual pathway and anatomical connectivity of auditory and visual thalamus-cortical radiations were evaluated in a sample of eight patients. In general, there was a positive relationship of middle latency response (MLR) latency and length of resection, while a negative correlation was found between MLR latency and the anatomical connection strength and anatomical connection probability of the auditory radiations. In the visual pathway, significant differences between sides were found with respect to the number and length of tracts, which was lower in the operated one. Anatomical connectivity variables and perimetry (visual field defect index) were particularly correlated with the latency of P100 wave which was obtained by quadrant stimulation. These results demonstrate an indirect functional modification of the auditory pathway and a direct traumatic lesion of the visual pathway after anterior temporal lobectomy in patients with drug resistant epilepsy.

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RESUMO Objetivo Verificar como os limiares obtidos pelas respostas auditivas de estado estável (RAEE) podem estimar os limiares obtidos pela audiometria com reforço visual (VRA), em crianças com audição normal e perda auditiva de diversos graus. Métodos Foram avaliadas 41 crianças de ambos os sexos (28 crianças do sexo masculino e 13 do sexo feminino), com faixa etária de 18 a 48 meses. Foram pesquisadas as frequências de 500, 1000, 2000 e 4000 Hz, em ambos os métodos de avaliação, e avaliadas as orelhas separadamente, totalizando 82 orelhas, sendo 20 com audição normal e 62 com perda auditiva. Os limiares foram analisados para calcular suas correlações e outras variáveis. Resultados Os limiares não variaram significativamente, nem com a idade, nem com o sexo. Em média, foram observados limiares eletrofisiológicos maiores que os limiares comportamentais. Conclusão A técnica da RAEE possibilita a determinação dos limiares auditivos objetivamente, com uma considerável correlação com os limiares psicoacústicos, concordando com a literatura. Recomenda-se, entretanto, a realização de novos estudos brasileiros, que visem ao estabelecimento de critérios mínimos necessários para o planejamento e aplicação de protocolos, com fins de padronização, contribuindo com a validação diagnóstica.

ABSTRACT Purpose The objective of the following study was to verify how the thresholds obtained by ASSR can estimate the thresholds obtained by the VRA in children with normal hearing and hearing loss of different degrees. Methods Were evaluated 41 children of both sex (28 boys and 13 girls), on ages between 18 and 48 months. The thresholds were obtained with ASSR with multiple and simultaneous stimulation on frequencies of 500, 1000, 2000 and 4000Hz. The thresholds were obtained with VRA on each ear separately on frequencies of 500, 1000, 2000 and 4000Hz. Were evaluated 82 ears, 20 with normal hearing and 62 with hearing loss. The correlation between the thresholds was calculated. Results The findings of this study demonstrate that the thresholds didn't have a statistic relevant relation with variables of age and sex. Considering the mean, the eletrophysiological thresholds were higher than the behavioral. These findings suggest ASSR can determinate hearing thresholds objectively and with a high correlation with psychoacoustic thresholds obtained by the behavioral method. Conclusion We recommend, however that another Brazilian studies be made, so it can be established a minimum criteria necessary for the planning and application of pattern protocols, contributing with diagnostic validation of ASSR technique.

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The spectral local F-test has been applied for detecting evoked responses to rhythmic stimulation that are embedded in the ongoing electroencephalogram (EEG). Based on the sampling distribution of a flat spectrum at the neighbourhood of the stimulation frequency, spectral peaks in an EEG signal that are due to the stimulation may be readily assessed. Nevertheless, the performance of the technique is strongly affected by both the signal-to-noise ratio (SNR) of the responses and the number of data segments used in the estimation. The present work aims at both deriving and evaluating a multivariate extension of local F-test by including the EEG collected at a second distinct derivation. The detection rate with this multivariate detector was found to be greater than that using a single channel in case of equal SNR in both signals. Monte Carlo simulation results showed that the probability of detection with this new detector saturates for signal-to-noise ratios above 12 dB and indicated a greater detection rate in practical situations, even when smaller SNR-values are found in the added signal (e.g. 5 dB for 16 neighbouring frequencies used in the estimation). The technique was next applied to the EEG from 12 subjects during intermittent, photic stimulation leading to superior performance in comparison with the univariate local F-test. Since a higher detection rate with the proposed technique is achieved without the need of increasing the number of data segments, it allows evoked responses to be detected faster, once the same detection rate may be accomplished with less segments. This might be useful in clinical practice.

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The present study aimed to analyse the wave morphology, amplitude, latency, and intervals of the brainstem auditory evoked responses (BAERs) in dogs with central vestibular syndrome (CVS) recorded with surface electrodes. Ten dogs with CVS were examined by mono- and binaural stimulation, using the Neuropack electrodiagnostic system, with stimulus intensities of 90 dBSPL. BAERs examinations revealed morphological changes of waves I, II, III, and V and decreased amplitudes of all waves in 7/10 dogs. P values obtained were = 0.014 for wave I amplitude, 0.031 for II, and III and 0.032 for V. Comparing the latencies of waves I, II, III, and V generated by right and left monoaural stimulation in dogs with CVS, we did not observe significant differences (P > 0.05). No statistical differences were observed for BAERs latencies of the waves recorded after binaural and monaural stimulation (left or right). As far as we know, this is the first study of BAERs using surface electrodes, obtained from dogs with CVS.(AU)

Este estudo destina-se à análise da morfologia, da amplitude, da latência e do intervalo das ondas das respostas evocadas auditivas no tronco cerebral (BAERs) em cães com síndrome vestibular central (CVS) registrados com eletrodos de superfície. Dez cães com CVS foram examinados por estimulação mono e binaural usando um sistema de eletrodiagnóstico Neuropack, com intensidade do estímulo de 90 dBSPL. Os exames BAERs relevaram alterações morfológicas das ondas I, II, III e V, bem como baixas amplitudes para todas as ondas no caso dos 7/10 cães. Os valores de P obtidos foram = 0.014 para ampitude da onda I, 0.031 para a II e 0.032 para a V. Compararam-se as latências das ondas I, II, III e V geradas pelo estímulo monoaural direito e esquerdo em cães com CVS e não foram constatadas diferenças significativas (P > 0.05). Igualmente não foram observadas diferenças estatísticas no caso das latências BAERs no que diz respeito às ondas gravadas depois de estímulos binaural e monoaural (esquerdo ou direito). Pelo que é de conhecimento dos autores da presente pesquisa, este é o primeiro estudo sobre BAERs usando eletrodos de superfície obtidos em cães com CVS.(AU)

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The present study aimed to analyse the wave morphology, amplitude, latency, and intervals of the brainstem auditory evoked responses (BAERs) in dogs with central vestibular syndrome (CVS) recorded with surface electrodes. Ten dogs with CVS were examined by mono- and binaural stimulation, using the Neuropack electrodiagnostic system, with stimulus intensities of 90 dBSPL. BAERs examinations revealed morphological changes of waves I, II, III, and V and decreased amplitudes of all waves in 7/10 dogs. P values obtained were = 0.014 for wave I amplitude, 0.031 for II, and III and 0.032 for V. Comparing the latencies of waves I, II, III, and V generated by right and left monoaural stimulation in dogs with CVS, we did not observe significant differences (P > 0.05). No statistical differences were observed for BAERs latencies of the waves recorded after binaural and monaural stimulation (left or right). As far as we know, this is the first study of BAERs using surface electrodes, obtained from dogs with CVS.(AU)

Este estudo destina-se à análise da morfologia, da amplitude, da latência e do intervalo das ondas das respostas evocadas auditivas no tronco cerebral (BAERs) em cães com síndrome vestibular central (CVS) registrados com eletrodos de superfície. Dez cães com CVS foram examinados por estimulação mono e binaural usando um sistema de eletrodiagnóstico Neuropack, com intensidade do estímulo de 90 dBSPL. Os exames BAERs relevaram alterações morfológicas das ondas I, II, III e V, bem como baixas amplitudes para todas as ondas no caso dos 7/10 cães. Os valores de P obtidos foram = 0.014 para ampitude da onda I, 0.031 para a II e 0.032 para a V. Compararam-se as latências das ondas I, II, III e V geradas pelo estímulo monoaural direito e esquerdo em cães com CVS e não foram constatadas diferenças significativas (P > 0.05). Igualmente não foram observadas diferenças estatísticas no caso das latências BAERs no que diz respeito às ondas gravadas depois de estímulos binaural e monoaural (esquerdo ou direito). Pelo que é de conhecimento dos autores da presente pesquisa, este é o primeiro estudo sobre BAERs usando eletrodos de superfície obtidos em cães com CVS.(AU)

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INTRODUCTION: The middle-latency auditory evoked potential is used to evaluate any abnormality that might impair the central auditory pathways, which are situated between the brain stem and the primary auditory cortex OBJECTIVE: To analyse the middle-latency auditory evoked potentials in children Methods : This is a descriptive and cross-sectional study. Pure-tone audiometry was performed, and if no change was detected, Biologic's portable Evoked Potential System (EP) was used to measure auditory evoked potentials. The identification of the responses was performed using electrodes positioned at C3 and C4 (left and right hemispheres) in reference to ears A1 and A2 (left and right earlobe). These were ipsilaterally and contralaterally paired and landed at Fpz (forehead), in two steps, with alternating stimulation of the right and left ears. RESULTS: In this study, there was 100% detectability of the Na, Pa, and Nb components and interamplitude Na-Pa. This study compared different electrode leads, and there was no significant difference between the different electrode positions studied for the right and left ears in the studied population CONCLUSION: It was concluded that the examination of middle-latency evoked potential is steady and feasible for the studied age group regardless of electrode position

INTRODUÇÃO: O potencial evocado auditivo de média latência é utilizado na avaliação de qualquer anomalia que possa comprometer as vias auditivas centrais, situadas entre o tronco encefálico e córtex auditivo primário OBJETIVO: Analisar os potenciais evocados auditivos de média latência em escolares MÉTODO: Esse estudo é descritivo transversal. Como procedimento foi realizado a audiometria tonal, e caso não fosse detectada nenhuma alteração, foi utilizado o equipamento portátil de potencial evocado auditivo Biologic's Evoked Potencial System (EP). O registro das respostas foi efetuado com eletrodos posicionados em C3 e C4 (hemisfério esquerdo e direito, respectivamente) em referência às orelhas A1 (lóbulo da orelha esquerda) e A2 (lóbulo da orelha direita), pareados ipsilateralmente e contralateralmente e terra em Fp (fronte), em duas etapas, alternando as estimulações das orelhas direita e esquerda RESULTADOS: Neste estudo houve 100% de detectabilidade dos componentes Na, Pa, Nb e interamplitude Na-Pa. Foram comparadas diferentes derivações de eletrodo e não foi observada diferença significativa entre diferentes posições de eletrodos pesquisadas tanto para orelha direita quanto para orelha esquerda nesta população de estudo CONCLUSÃO: O exame de potencial evocado auditivo de média latência é estável e viável para faixa etária estudada independente da posição dos eletrodos

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Evocado auditivo de respostas ­ BAER ) foi gravado utilizando eletrodos de superfície em sete cães Mastiff argentino saudáveis para estimulações monoaural e binaural em intensidades sonoras de 90 dB NPS . As latências e amplitudes das ondas I, III e V bem como os intervalos InterWave I- III , III -V e IV foram calculados. As diferenças estatísticas foram obtidas para as ondas III e latências V, amplitudes das ondas III e intervalos I- III e I-V entre mono e estimulação binaural. Por serem uma das raças geneticamente predispostas à surdez congênita, obtendo valores de referência BAER, os cães Mastiff argentino têm uma importância clínica especial.(AU)

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Evocado auditivo de respostas ­ BAER ) foi gravado utilizando eletrodos de superfície em sete cães Mastiff argentino saudáveis para estimulações monoaural e binaural em intensidades sonoras de 90 dB NPS . As latências e amplitudes das ondas I, III e V bem como os intervalos InterWave I- III , III -V e IV foram calculados. As diferenças estatísticas foram obtidas para as ondas III e latências V, amplitudes das ondas III e intervalos I- III e I-V entre mono e estimulação binaural. Por serem uma das raças geneticamente predispostas à surdez congênita, obtendo valores de referência BAER, os cães Mastiff argentino têm uma importância clínica especial.(AU)

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CONCLUSION: Responses with greater amplitude were recorded when carrier frequencies were modulated at 37, 40, and 43 Hz. These responses can be recorded even in patients with significant sensorineural hearing loss, from the sternocleidomastoid (SCM) muscle for a 500 Hz tone, 100% modulated at 40 Hz. OBJECTIVE: To determine the best carrier and modulating frequencies to evoke steady-state myogenic responses. METHODS: The present study investigated 156 ears of 78 normal-hearing young adults, with carrier frequencies of 250, 500, and 1000 Hz, modulated at 20, 37, 40, 43, 70, 77, and 80 Hz, with an intensity of 95 dBA. Furthermore, we observed responses evoked by stimulus carrier frequency of 500 Hz, modulated at 40 Hz, with an intensity of 95 dBA in a group of five subjects with severe sensorineural loss. RESULTS: Responses were found for all stimuli studied (p < 0.01). Modulated stimuli at frequencies of 37, 40, and 43 Hz evoked better steady-state vestibular evoked myogenic potential (S-VEMP) (p < 0.05). No statistically significant differences were found between the group of normal hearers and the group of subjects with hearing loss (p = 0.431), for the stimulus used.

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A cross-sectional study included all children diagnosed with congenital toxoplasmosis, through the Minas Gerais State Neonatal Screening Program, from September 2006 to March 2007. All children received early treatment, initiated before the age of 2.5 months, and were periodically assisted by a team of specialists including pediatricians, ophthalmologists and speech-language therapists and audiologists. Hearing function was evaluated with the following procedures: tympanometry, transient evoked otoacoustic emissions, distortion product otoacoustic emissions, behavioral observation audiometry, and brainstem auditory evoked potentials. Hearing function and sensitivity was estimated and audiological results were classified as normal, conductive hearing loss, sensory-neural hearing loss and central dysfunction. Language performance was assessed and classified as normal or abnormal, according to test results. The following variables were studied: audiological results, neurological and ophthalmological conditions, language performance and presence of risk indicator for hearing loss other than congenital toxoplasmosis. Univariate analysis was conducted using the chi-square or Fisher?s Exact test. Results: From September 2006 to March 2007, 106 children were diagnosed with congenital toxoplasmosis through the neonatal screening program, and were included in the study. Data analysis showed normal hearing in 60 children (56.6%), while 13 children (12.3%) had conductive hearing loss, four children (3.8%) had sensory-neural hearing loss and 29 children (27.4%) presented central hearing dysfunction. There was association between hearing problems and language deficits. The comparison between children with additional risks for hearing loss other than toxoplasmosis and children who only presented toxoplasmosis as a risk factor showed no differences. This finding suggests that audiological problems were due to congenital toxoplasmosis alone.

Um estudo transversal descritivo incluiu todas as crianças diagnosticadas com toxoplasmose congênita (TC) pelo Prog. Est. de Tria. Neonatal de MG entre set. 2006 e mar. de 2007. Todas as crianças foram submetidas ao protocolo de tratamento com pirimetamina e sulfadiazina iniciado antes dos 2,5 meses de idade e com duração de 12 meses, tendo realizado acompanhamento pediátrico, oftalmológico e fonoaudiológico periódico. Para avaliar a audição foram usados, como instrumentos diagnósticos, medidas de imitância acústica, emissões otoacústicas evocadas por estímulo transiente e produto de distorção, potencial evocado auditivo de tronco encefálico e observação do comportamento auditivo. Foi avaliada a acuidade auditiva e as alterações auditivas foram classificadas em condutivas, neurossensoriais e retrococleares. O desempenho de ling. foi avaliado usando-se um instrumento de aval. do desenvolvimento da ling., e os resultados foram classificados como normais ou alterados. As seguintes variáveis foram estudadas: resultados audiológicos, condições neurológicas e oftalmológicas, linguagem e presença de fator de risco para perda auditiva além da TC. Foi realizada análise univariada pelo qui-quadrado ou teste exato de Fisher. Resultados: entre set. 2006 e mar. 2007, 106 crianças foram diagnos. com TC pelo programa de triagem neonatal, sendo incluídas no estudo. A análise dos dados mostrou que 60 crianças apresentavam audição normal (56,6%) e 46 crianças apresentavam audição alterada, sendo 13 crianças (12,3%) com alteração condutiva, 4 (3,8%) com perda auditiva neurossensorial e 29 (27,4%) com comprometimento retrococlear. Houve associação entre presença de alteração auditiva e déficit de linguagem. A comparação entre crianças que apresentavam outro fator de risco além da TC e crianças que apresentavam somente a toxoplasmose como fator de risco para alteração auditiva não mostrou diferenças.

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The study of brainstem auditory evoked potentials (BAEP) allows obtaining the electrophysiological activity generated in the cochlear nerve to the inferior colliculus. In the first months of life, a period of greater neuronal plasticity, important changes are observed in the absolute latency and inter-peak intervals of BAEP, which occur up to the completion of the maturational process, around 18 months of life in full-term newborns, when the response is similar to that of adults. OBJECTIVE: The goal of this study was to establish normal values of absolute latencies for waves I, III and V and inter-peak intervals I-III, III-V and I-V of the BAEP performed in full-term infants attending the Infant Hearing Health Program of the Speech-Language Pathology and Audiology Course at Bauru School of Dentistry, Brazil, with no risk history for hearing impairment. MATERIAL AND METHODS: The stimulation parameters were: rarefaction click stimulus presented by the 3ª insertion phone, intensity of 80 dBnHL and a rate of 21.1 c/s, band-pass filter of 30 and 3,000 Hz and average of 2,000 stimuli. A sample of 86 infants was first divided according to their gestational age in preterm (n=12) and full-term (n=74), and then according to their chronological age in three periods: P1: 0 to 29 days (n=46), P2: 30 days to 5 months 29 days (n=28) and P3: above 6 months (n= 12). RESULTS: The absolute latency of wave I was similar to that of adults, generally in the 1st month of life, demonstrating a complete process maturity of the auditory nerve. For waves III and V, there was a gradual decrease of absolute latencies with age, characterizing the maturation of axons and synaptic mechanisms in the brainstem level. CONCLUSION: Age proved to be a determining factor in the absolute latency of the BAEP components, especially those generated in the brainstem, in the first year of life.

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