Purpose: To analyze the latency and amplitude of P300 responses obtained with electrodes positioned at Cz and Fz and in different tasks of infrequent stimulus identification in normal hearing individuals. Methods: Forty adults of both genders participated in the study. Three recordings with three different tasks were obtained for the identification of the infrequent stimulus; simultaneous recordings were obtained from Cz and Fz positions. Results: Cz position showed significantly greater amplitudes and lower latencies than Fz. Regarding the three tasks, only "pronouncing the word 'thin'" was different from "raising a finger", with lowest latencies for the verbal task. Regarding amplitude, significantly higher values were observed for "raising a finger", followed by "pronouncing the word 'thin'" and mental counting. Conclusion: Cz obtained the best values, highest amplitude and lowest latency. Lowest latencies were obtained for the task of "pronouncing the word 'thin'" and the highest amplitudes were obtained for "raising a finger".
The English version of the Amsterdam inventory for auditory disability and handicap could be translated and adapted to Brazilian Portuguese. An analyses of the validation process yielded reliable, consistent, and stable results.
Introduction The P300 test requires well-defined and unique criteria, in addition to training for the examiners, for a uniform analysis of studies and to avoid variations and errors in the interpretation of measurement results. Objectives The objective of this study is to verify whether there are differences in P300 with and without subtraction of traces of standard and nonstandard stimuli. Method We conducted this study in collaboration with two research electrophysiology laboratories. From Laboratory 1, we selected 40 tests of subjects between 7–44 years, from Laboratory 2, we selected 83 tests of subjects between 18–44 years. We first performed the identification with the nonstandard stimuli; then, we subtracted the nonstandard stimuli from the standard stimuli. The examiners identified the waves, performing a descriptive and comparative analysis of traces with and without subtraction. Results After a comparative analysis of the traces with and without subtraction, there was no significant difference when compared with analysis of traces in both laboratories, within the conditions, of right ears ( p = 0.13 and 0.28 for differences between latency and amplitude measurements) and left ears ( p = 0.15 and 0.09 for differences between latency and amplitude measurements) from Laboratory 1. As for Laboratory 2, when investigating both ears, results did not identify significant differences ( p = 0.098 and 0.28 for differences between latency and amplitude measurements). Conclusion There was no difference verified in traces with and without subtraction. We suggest the identification of this potential performed through nonstandard stimuli.
Introdução: O consumo de bebidas alcoólicas por gestantes acarreta alterações de formação e de desenvolvimento fetal, incluindo alterações estruturais e funcionais do Sistema Nervoso Central. Os comprometimentos sensoriais de crianças expostas ao álcool na gestação, como a audição, são uma das morbidades relatadas nesta população. A ocorrência de alteração da sensitividade auditiva é melhor conhecida, mas o envolvimento do sistema nervosos auditivo central ainda carece de pesquisas. Objetivo: Estudar a função auditiva, periférica e central, em crianças em idade escolar com expostas ao álcool no período pré-natal. Métodos: Foram avaliadas 45 crianças, de ambos os gêneros, com 13 e 14 anos, provenientes do projeto INFANTO-ÁLCOOL, divididas em grupo exposto (GE) e não exposto (GNE) ao álcool na gestão. Foram realizadas audiometria tonal limiar, imitânciometria, emissões otoacústicas transientes (EOA-T), potencial evocado auditivo de tronco encefálico (PEATE) e o potencial evocado auditivo tardio, potencial evocado auditivo de longa latência (PEALL) e relacionado a eventos (PEARE), registrado em Cz e Pz. Foi realizada a análise comparativa entre grupos. Resultados: Apenas uma criança do GE apresentou perda auditiva unilateral do tipo mista, sendo os demais com limiares auditivos dentro da normalidade, com predominância de curva timpanomética do tipo "A" e presença de reflexo contralateral. Quanto ao funcionamento coclear e avaliação comportamental do processamento auditivo, não houve diferença entre grupos. Embora os resultados do PEATE tenham sido sugestivos de alteração na sincronia neural em nível de tronco encefálico, a diferença entre grupos não foi apontada. Para o PEALL, o GE apresentou menor amplitude de P2, na derivação Pz; no PEARE maiores amplitudes de P3a foram evidenciadas no GE, em Cz. Na comparação entre os eletrodos ativos foi possível constatar maior identificação da P3 com duplo pico para o eletrodo em Pz. Conclusão: O perfil de exposição fetal ao álcool em qualquer trimestre gestacional, esteve relacionado a alteração na sincronia neural em nível de tronco encefálico, bem como na identificação das componentes P2 e P3a.
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