Cortical auditory evoked potentials in full-term and preterm neonates

DOI: 10.1590/2317-1782/20162015291 Cortical auditory evoked potentials in full‑term and preterm neonates Original Article Artigo Original Ândrea de Melo1,2 Eliara Pinto Vieira Biaggio2 Inaê Costa Rechia2 Pricila Sleifer1 Keywords Evoked Potentials Evoked Potentials Auditory Newborn Electrophysiology Infant, Premature Descritores Potenciais Evocados Potenciais Evocados Auditivos Recém-nascido Eletrofisiologia Prematuridade Correspondence address: Ândrea de Melo Universidade Federal do Rio Grande do Sul – UFRGS Rua Cassilda Genro, 1540, Bairro Maria Alice Gomes, Santiago (RS), Brazil, CEP: 97700-000. E-mail: Potenciais evocados auditivos corticais em neonatos nascidos a termo e pré-termo ABSTRACT Purpose: To measure the exogenous components of the cortical auditory evoked potential (CAEP) in term and preterm newborns and compare them considering the variables latency and amplitude. Methods: This is a cross-sectional, prospective, comparative, contemporary study. One hundred twenty-seven newborns were evaluated; 96 of these were included in the study after analysis of the exams by three referees. Participants were divided into two groups: Term Group: 66 infants and Preterm Group: 30 neonates. The recordings of CAEP were performed using surface electrodes with newborns comfortably positioned in the lap of their mothers and/or guardians in natural sleep. To this end, binaural verbal stimuli were presented with /ba/ as the frequent stimulation and /ga/ the rare stimulus, at an intensity of 70 dB HL, through insert earphones. The presence or absence of exogenous components and the latency and amplitude of P1 and N1 were analyzed in both groups. Pertinent tests were used in the statistical analysis of data. Results: The latency of the waves P1 and N1 was smaller in participants in the Term Group. However, there were no statistically significant differences in the amplitude of P1 and N1 between the groups. No difference between the groups was found when comparing the presence and absence of the components P2 and N2. Conclusion: It is possible to measure the CAEP in term and preterm neonates. There was influence of the maturational process only on the measure of latency of the components P1, binaurally, and N1, in the left ear, which were smaller in participants in the Term Group. RESUMO Objetivo: Mensurar os potenciais exógenos do potencial evocado auditivo cortical (PEAC) em neonatos nascidos a termo e pré-termo, além de compará-los considerando as variáveis latência e amplitude dos componentes. Método: Estudo transversal, prospectivo, contemporâneo e comparativo. Foram avaliados 127 neonatos; destes, foram considerados 96, após análise dos exames por três juízes, distribuídos em dois grupos: Grupo Termo: 66 neonatos e Grupo Pré-termo: 30 neonatos. Os registros do PEAC foram feitos com os neonatos posicionados no colo da mãe e/ou responsável, em sono natural, por meio de eletrodos de superfície. Foram apresentados estímulos verbais binauralmente, sendo /ba/ o estímulo frequente e /ga/ o estímulo raro, na intensidade de 70 dBNA, por meio de fones de inserção. Foi analisada a presença ou ausência dos componentes exógenos em ambos os grupos, bem como, latência e amplitude de P1 e N1. Para análise dos dados, utilizaram-se os testes pertinentes. Resultados: A latência da onda P1 bilateralmente e N1 na orelha esquerda foi menor no Grupo Termo. No entanto, não houve diferença estatisticamente significante quanto à amplitude de P1 e N1 entre os grupos. Na comparação entre presença e ausência dos componentes P2 e N2, também não foi observada diferença entre os grupos. Conclusão: É possível mensurar os PEAC, em neonatos nascidos a termo e pré-termo. Verificou-se influência do processo maturacional apenas na medida da latência dos componentes P1 bilateralmente e N1 na orelha esquerda, sendo estas menores no Grupo Termo. Study carried out at Universidade Federal de Santa Maria – UFSM - Santa Maria (RS), Brazil. 1 Universidade Federal do Rio Grande do Sul – UFRGS - Porto Alegre (RS), Brazil. 2 Universidade Federal de Santa Maria – UFSM - Santa Maria (RS), Brazil. Financial support: nothing to declare. Conflict of interests: nothing to declare. Received: December 03, 2015 Accepted: March 08, 2016 CoDAS 2016;28(5):491-496 Melo A, Biaggio EPV, Rechia IC, Sleifer P 492 INTRODUCTION Objective electrophysiologic testing allows measurement or observation of the function of peripheral and central auditory pathways. These tests are of paramount importance for complementary assessment, aiming at an accurate diagnosis and/or understanding of the auditory status, especially when conducted with populations that present difficulties to respond satisfactorily to behavioral evaluations, such as neonates, infants, and young children. Electrophysiologic and electroacoustic methods of assessment are used as routine tests in newborn hearing screening (NHS) by means of transient evoked otoacoustic emissions (TEOAE) and/or brainstem auditory evoked potentials - automated (BAEP-A)(1,2). Nevertheless, there are other electrophysiologic procedures that can be included in the audiology process to enhance the diagnostics, e.g., brainstem auditory evoked potential (BAEP) and auditory steady state response (ASSR), which can measure the auditory electrophysiologic hearing thresholds, as well as visualize the audiometric configuration. With technological and scientific development, other tests such as long latency auditory evoked potential (LLAEP) and cortical auditory evoked potential (CAEP) are currently in use, allowing a variety of clinical applications(3). An example of the possibilities of these procedures is the monitoring of auditory maturation in neonates, considering that these assessments allow us to observe auditory pathway responses until the cerebral cortex, through the auditory stimulus. In addition, if this maturation is observed longitudinally, it will allow us to infer on how the auditory system is organized with respect to sound reception at cortical level over time. It is worth mentioning that LLAEP measures bioelectric responses of the cortical and thalamic activities at a time interval ranging from 80 to 600 ms(3,4). In adults and older children with normal hearing, it is possible to observe the presence of all components, both positive (P1, P2 and P3) and negative (N1 and N2). Components P1, N1, P2 and N2 are characterized as exogenous potentials, which are influenced by the physical characteristics present in the acoustic stimulus, such as intensity, frequency, and duration; whereas component P3 is an endogenous potential, which is predominantly related to cognitive skills such as attention to the acoustic stimulus(5). This endogenous potential, P3, appears when the individual consciously realizes a change in the sound stimulus presented(5). Moreover, the wave N2 presents greater negativity in children under five years old, becoming stable only after this age. Exogenous potentials (...truncated)