Cortical auditory-evoked potential as a biomarker of central auditory maturation in term and preterm infants during the first 3 months

OBJECTIVES: To analyze central auditory maturation in term and preterm infants during the first 3 months of life by comparing the latency and amplitude of cortical auditory-evoked potential at different frequencies. METHODS: In this study, 17 term and 18 preterm infants were examined; all had tested positive on the neonatal hearing screening test. Cortical auditory potential was investigated during the first and third months of life. The response of the cortical auditory-evoked potential was investigated at frequencies of 500, 1000, 2000, and 4000 Hz. The latency and amplitude of the cortical response were automatically detected and manually analyzed by three researchers with experience in electrophysiology. The results were compared using analysis of variance and the Bonferroni test. A significance level of 5% was used for all analyses. RESULTS: Latency values of cortical auditory-evoked potential in the first month of birth were significantly higher than those in the third month, and latency values of the preterm group were higher than those of the term group, regardless of the frequency and time of evaluation. In general, the latency of the cortical auditory-evoked potential was higher at high frequencies. Amplitude values in the third month of life were significantly higher than those in the first month for term and preterm infants. CONCLUSION: Central auditory maturation was observed in both groups but with different results between those born at term and preterm, with latencies of cortical auditory-evoked potential higher for the preterm group and at high frequencies.

Cortical auditory evoked potential in assessment of neonates: a study about minimum level of responses in term and preterm newborns / Potencial evocado auditivo cortical na avaliac¸ão de neonatos: um estudo sobre o nível mínimo de respostas em nascidos a termo e pré-termos

Abstract Introduction: The study of the threshold level of cortical auditory response in adults has been investigated in previous studies. Due to maturational issues, little is known about these responses in neonates. Technological advances with automatic analysis devices now allow investigation in specific populations. Thus, new studies are needed to establish the feasibility of using this auditory potential to identify the lowest levels of responses in children. Objective: Verify and compare latency and amplitude in 80 dBnNA and the minimum level of cortical auditory response in term and preterm neonates. Methods: A cross-sectional, comparative study involving 59 neonates, 35 full-term births and 24 preterm births, with positive results in the Neonatal Hearing Screening. The Hearlab system was used to investigate the P1i auditory potential with tone burst stimulus at frequencies of 500, 1000, 2000 and 4000 Hz. The minimum response level search ranged from 80 to 0 dBNA and was detected automatically. The results were compared between groups, evaluating the latency and amplitude in 80 dBNA and the minimum level of cortical auditory response. Results: The mean values obtained for the minimum level of cortical auditory response in term group were 26 ± 8.81; 26.14 ± 6.97; 29 ± 7.65 and 29.43 ± 7.04 dBNA and for preterm neonates of 31.96 ± 10.41; 34.13 ± 11.34; 33.64 ± 11.03 and 37.73 ± 11.92 dBNA, for the frequencies of 500, 1000, 2000 and 4000 Hz, respectively. There was a difference between groups for the latency of P1i at 4000 Hz and the minimum response levels at 500, 1000 and 4000 Hz, with higher values for preterm infants. Conclusion: It was possible to obtain latency and amplitude values at 80 dBnNA and the minimum level of cortical response in term and preterm newborns, with different results between groups, with higher values in those born preterm.

Resumo Introdução: A investigação do nível mínimo de resposta auditiva cortical tem sido alvo de diferentes estudos em adultos. Devido a questões de maturação, pouco se sabe sobre essas respostas em recém-nascidos. Com o avanço tecnológico, dispositivos de análise automática surgiram com o objetivo de retomar essa avaliação em populações específicas. Assim, novos estudos são necessários para verificar a viabilidade do uso desse potencial auditivo na obtenção de níveis mínimos de respostas na criança. Objetivo: Verificar e comparar latência e amplitude em 80 dBnNA e o nível mínimo de resposta auditiva cortical em recém-nascidos a termo e pré-termo. Método: Estudo transversal, comparativo, envolvendo 59 neonatos, 35 nascidos a termo e 24 pré-termos, com resultados positivos na triagem auditiva neonatal. O sistema Hearlab foi utilizado para investigar o potencial auditivo P1i com estímulo tone burst nas frequências de 500, 1000, 2000 e 4000 Hz. A busca do nível mínimo de resposta variou de 80 a 0 dBNA e foi detectado automaticamente. Os resultados foram comparados entre os grupos, avaliando a latência e amplitude em 80 dBNA e o nível mínimo de resposta auditiva cortical. Resultados: Os valores médios obtidos para o nível mínimo de resposta auditiva cortical no grupo nascido a termo foram 26 ± 8,81; 26,14 ± 6,97; 29 ± 7,65 e 29,43 ± 7,04 dBNA e para recém-nascidos pré-termos foram de 31,96 ± 10,41; 34,13 ± 11,34; 33,64 ± 11,03 e 37,73 ± 11,92 dBNA, para as frequências de 500, 1000, 2000 e 4000 Hz, respectivamente. Houve diferenc¸a entre os grupos para a latência de P1i em 4000 Hz e os níveis mínimos de resposta em 500, 1000 e 4000 Hz, com valores maiores em Pré-termos. Conclusão: Foi possível obter valores de latência e amplitude em 80 dBnNA e o nível mínimo de resposta cortical em recém-nascidos a termo e Pré-termos, com resultados diferentes entre osgrupos, com valores maiores em pré-termos.

Automated cortical auditory evoked potentials threshold estimation in neonates / Estimativa do limiar de potenciais evocados auditivos corticais automatizados em recém-nascidos

Abstract Introduction: The evaluation of cortical auditory evoked potential has been the focus of scientific studies in infants. Some authors have reported that automated response detection is effective in exploring these potentials in infants, but few have reported their efficacy in the search for thresholds. Objective: To analyze the latency, amplitude and thresholds of cortical auditory evoked potential using an automatic response detection device in a neonatal population. Methods: This is a cross-sectional, observational study. Cortical auditory evoked potentials were recorded in response to pure-tone stimuli of the frequencies 500, 1000, 2000 and 4000 Hz presented in an intensity range between 0 and 80 dB HL using a single channel recording. P1 was performed in an exclusively automated fashion, using Hotelling's T2 statistical test. The latency and amplitude were obtained manually by three examiners. The study comprised 39 neonates up to 28 days old of both sexes with presence of otoacoustic emissions and no risk factors for hearing loss. Results: With the protocol used, cortical auditory evoked potential responses were detected in all subjects at high intensity and thresholds. The mean thresholds were 24.8 ± 10.4 dB NA, 25 ± 9.0 dB NA, 28 ± 7.8 dB NA and 29.4 ± 6.6 dB HL for 500, 1000, 2000 and 4000 Hz, respectively. Conclusion: Reliable responses were obtained in the assessment of cortical auditory potentials in the neonates assessed with a device for automatic response detection.

Resumo Introdução: O potencial evocado auditivo cortical tem sido o foco de estudos científicos. Alguns autores observaram que a detecção automatizada de respostas é eficaz na exploração desses potenciais em lactentes, mas poucos relataram sua eficácia na busca de limiares. Objetivo: Analisar a latência, a amplitude e os limiares do potencial evocado auditivo cortical em recém-nascidos, com o uso de um dispositivo de detecção automática de resposta. Método: Estudo transversal, observacional. Os potenciais evocados auditivos corticais foram registrados em resposta a estímulos de tons puros nas frequências de 500, 1000, 2000 e 4000 Hz e apresentados em uma faixa de intensidade entre 0-80 dBNA, com o uso de gravação de canal único. O P1 foi feito de forma exclusivamente automática, com o uso do teste estatístico T2 de Hotelling. A latência e a amplitude foram obtidas manualmente por três examinadores. O estudo incluiu 39 recém-nascidos com até 28 dias de ambos os sexos, com presença de emissões otoacústicas e sem fatores de risco para perda auditiva. Resultados: Com o protocolo usado, as respostas dos PEAC foram detectadas em todos os indivíduos em alta intensidade e limiares. Os limiares médios foram 24,8 ± 10,4 dBNA, 25 ± 9,0 dBNA, 28 ± 7,8 dBNA e 29,4 ± 6,6 dBNA para 500, 1000, 2000 e 4000 Hz, respectivamente. Conclusão: Foram obtidas respostas confiáveis na avaliação dos potenciais auditivos corticais em recém-nascidos com um dispositivo para detecção de resposta automática.

Efeito do estado atencional na detecção automática das respostas auditivas corticais em neonatos / Effect of the arousal state on automatic detection of cortical auditory evoked responses in neonates

RESUMO Objetivo O objetivo desse estudo foi comparar a latência e amplitude do potencial evocado auditivo cortical P1i entre neonatos em estado de alerta e durante o sono leve. Métodos Vinte e cinco neonatos com emissões otoacústicas evocadas transientes presentes foram testados, por meio do potencial evocado auditivo cortical (PEAC), sendo dez em estado de alerta e 15 durante o sono leve. Para pesquisa dos potenciais corticais, utilizou-se o equipamento Hearlab System, de um canal, no módulo Cortical Tone Evaluation (CTE). O potencial P1i foi pesquisado de forma monoaural, na intensidade de 80 dBnNA, para as frequências de 500, 1000, 2000 e 4000Hz. A detecção do P1i foi feita de maneira automática pelo equipamento. A marcação da latência e amplitude foi realizada por três juízes. Resultados Não houve diferença estatisticamente significativa entre os dois grupos de neonatos para os valores de amplitude e latência, nas quatro frequências testadas. Conclusão Não houve influência do estado comportamental dos neonatos na avaliação do potencial cortical P1i.

ABSTRACT Purpose The aim of the present study was to compare latency and amplitude of the cortical auditory evoked response P1i among newborns in an alert state and during light sleep. Methods Twenty-five neonates with normal transient evoked otoacoustic emissions were tested with cortical auditory evoked potentials (CAEP): 10 were in an alert state and 15 in light sleep during testing. For the investigation of cortical potentials, a single-channel Hearlab System equipment, Cortical Tone Evaluation module (CTE), was used. The P1i potential was investigated monoaurally at an 80dBnHL intensity at 500, 1000, 2000 and 4000 Hz. P1i was automatically detected by the equipment. Latency and amplitude were marked by three judges. The responses of the newborn in an alert state were compared with those in light sleep. Results There was no statistically significant difference between the two groups of neonates for the amplitude and latency values at the four tested frequencies. Conclusion There was no influence of the neonates' behavioral state on the evaluation of the P1i auditory cortical potential.