Department of Speech-Language Pathology and Audiology, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
J Appl Oral Sci. 2009;17 Suppl(spe):57-62. doi: 10.1590/s1678-77572009000700010.
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.
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.
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).
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.
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.
本研究旨在为参加巴西包鲁牙科学院言语病理学和听力学课程婴儿听力保健计划的足月婴儿建立脑干听觉诱发电位（BAEP）的 I、III 和 V 波绝对潜伏期以及 I-III、III-V 和 I-V 峰间潜伏期的正常参考值，这些婴儿无听力损伤风险史。
刺激参数为：3 号插入式耳机呈现的稀疏 click 刺激，强度为 80 dBnHL，速率为 21.1 c/s，带通滤波器为 30 和 3000 Hz，平均 2000 次刺激。首先根据胎龄将 86 名婴儿分为早产儿（n=12）和足月儿（n=74），然后根据其实际年龄分为三个时期：P1：0 至 29 天（n=46）、P2：30 天至 5 个月 29 天（n=28）和 P3：6 个月以上（n=12）。
I 波的绝对潜伏期与成人相似，通常在生命的第一个月，表明听神经的成熟过程已完全完成。对于 III 和 V 波，随着年龄的增长，绝对潜伏期逐渐降低，这表明脑干水平的轴突和突触机制的成熟。
年龄是影响 BAEP 成分绝对潜伏期的决定性因素，尤其是在生命的第一年中，在脑干中产生的那些成分。
