Cortical auditory evoked potential in assessment of neonates: a study about minimum level of responses in term and preterm newborns

IntroductionThe 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.ObjectiveVerify and compare latency and amplitude in 80 dBnNA and the minimum level of cortical auditory response in term and preterm neonates.MethodsA 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.ResultsThe 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.ConclusionIt 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.     

Automated cortical auditory evoked potentials threshold estimation in neonates

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.

Brainstem auditory evoked potentials with speech stimulus in neonates

IntroductionBrainstem auditory evoked potentials in response to complex sounds, such as speech sounds, investigate the neural representation of these sounds at subcortical levels, and faithfully reflect the stimulus characteristics. However, there are few studies that utilize this type of stimulus; for it to be used in clinical practice it is necessary to establish standards of normality through studies performed in different populations.ObjectiveTo analyze the latencies and amplitudes of the waves obtained from the tracings of brainstem auditory evoked potentials using speech stimuli in Brazilian neonates with normal hearing and without auditory risk factors.Methods21 neonates with a mean age of 9 days without risk of hearing loss and with normal results at the neonatal hearing screening were evaluated according to the Joint Committee on Infant Hearing protocols. Auditory evoked potentials were performed with speech stimuli (/da/ syllable) at the intensity of 80 dBNA and the latency and amplitude of the waves obtained were analyzed.ResultsIn the transient portion, we observed a 100% response rate for all analyzable waves (Wave I, Wave III, Wave V and Wave A), and these waves exhibited a latency <10 ms. In the sustained portion, Wave B was identified in 53.12% of subjects; Wave C in 75%; Wave D in 90.62%; Wave E in 96.87%; Wave F in 87.5% and Wave O was identified in 87.5% of subjects. The observed latency of these waves ranged from 11.51 ms to 52.16 ms. Greater similarity was observed for the response latencies, as well as greater amplitude variation in the studied group.ConclusionsAlthough the wave morphology obtained for brainstem evoked potentials with speech stimulation in neonates is quite similar to that of adults, a longer latency and greater variation in amplitude were observed in the waves analyzed.     

Long-latency auditory evoked potentials with verbal and nonverbal stimuli

IntroductionLong-latency auditory evoked potentials represent the cortical activity related to attention, memory, and auditory discrimination skills. Acoustic signal processing occurs differently between verbal and nonverbal stimuli, influencing the latency and amplitude patterns.ObjectiveTo describe the latencies of the cortical potentials P1, N1, P2, N2, and P3, as well as P3 amplitude, with different speech stimuli and tone bursts, and to classify them in the presence and absence of these data.MethodsA total of 30 subjects with normal hearing were assessed, aged 18–32 years old, matched by gender. Nonverbal stimuli were used (tone burst; 1000 Hz – frequent and 4000 Hz – rare); and verbal (/ba/ – frequent; /ga/, /da/, and /di/ – rare).ResultsConsidering the component N2 for tone burst, the lowest latency found was 217.45 ms for the BA/DI stimulus; the highest latency found was 256.5 ms. For the P3 component, the shortest latency with tone burst stimuli was 298.7 with BA/GA stimuli, the highest, was 340 ms. For the P3 amplitude, there was no statistically significant difference among the different stimuli. For latencies of components P1, N1, P2, N2, P3, there were no statistical differences among them, regardless of the stimuli used.ConclusionThere was a difference in the latency of potentials N2 and P3 among the stimuli employed but no difference was observed for the P3 amplitude.     

Study of brainstem auditory evoked potentials in early diagnosis of congenital toxoplasmosis

IntroductionCongenital toxoplasmosis is an infectious disease with high prevalence in tropical countries. It is characterized by neurological, ophthalmological and auditory sequelae.ObjectiveThe aim of this study was to evaluate and describe the brainstem auditory evoked potential in infants aged 1–3 months diagnosed with congenital toxoplasmosis and to compare them with infants of the same age group without the infection.MethodsThis is an observational, analytical and cross-sectional study in which brainstem auditory evoked potential was investigated in infants with congenital toxoplasmosis. The following audiological exams were performed: transient-evoked otoacoustic emissions, clinical and automatic brainstem auditory evoked potential.Results100 children participated in the study, but the final sample consisted of 76 children. Of the 37 children with toxoplasmosis included in the study, 28 completed the neurological imaging evaluation, and of these, 3 (10.7%) showed an altered neurological examination. At the brainstem auditory evoked potential assessment, two children without toxoplasmosis and 10 children with congenital toxoplasmosis had results suggestive of alterations in the brainstem auditory pathway maturation.Conclusion10 (27%) children were identified with a possible unilateral alteration in the electrophysiological assessment. There was a 5-fold higher risk for a child between 1 and 3 months of age with toxoplasmosis to have an altered brainstem auditory evoked potential compared to a child of the same age range without the infection.     

Mismatch negativity in children with specific language impairment and auditory processing disorder

IntroductionMismatch negativity, an electrophysiological measure, evaluates the brain's capacity to discriminate sounds, regardless of attentional and behavioral capacity. Thus, this auditory event-related potential is promising in the study of the neurophysiological basis underlying auditory processing.ObjectiveTo investigate complex acoustic signals (speech) encoded in the auditory nervous system of children with specific language impairment and compare with children with auditory processing disorders and typical development through the mismatch negativity paradigm.MethodsIt was a prospective study. 75 children (6–12 years) participated in this study: 25 children with specific language impairment, 25 with auditory processing disorders, and 25 with typical development. Mismatch negativity was obtained by subtracting from the waves obtained by the stimuli /ga/ (frequent) and /da/ (rare). Measures of mismatch negativity latency and two amplitude measures were analyzed.ResultsIt was possible to verify an absence of mismatch negativity in 16% children with specific language impairment and 24% children with auditory processing disorders. In the comparative analysis, auditory processing disorders and specific language impairment showed higher latency values and lower amplitude values compared to typical development.ConclusionThese data demonstrate changes in the automatic discrimination of crucial acoustic components of speech sounds in children with specific language impairment and auditory processing disorders. It could indicate problems in physiological processes responsible for ensuring the discrimination of acoustic contrasts in pre-attentional and pre-conscious levels, contributing to poor perception.     

Cervical vestibular evoked myogenic potentials in children

IntroductionCervical vestibular evoked myogenic potential is a test used in neurotological examination. It verifies the integrity of vestibular function through a muscular response evoked by an acoustic stimulation which activates the saccular macula. Normal standards in adults have been established, however, there are few published data on the normal responses in children.ObjectiveTo establish normal standards for vestibular myogenic responses in children without neurotological complaints.MethodsThis study's design is a cohort with cross-sectional analysis. The sample consisted of 30 subjects, 15 females (50%) and 15 males (50%).ResultsThe age of the subjects ranged between 8 and 13 years, with a mean of 10.2 (± 1.7). P1 peak showed an average latency of 17.26 (± 1.78) ms and a mean amplitude of 49.34 (± 23.07) μV, and the N2 peak showed an average latency of 24.78 (± 2.18) ms and mean amplitude of 66.23 (± 36.18) μV. P1–N2 mean amplitude was 115.6 (± 55.7) μV. There were no statistically significant differences when comparing by gender or by laterality.ConclusionWe established normal values of cervical myogenic vestibular responses in children between 8 and 13 years without neurotological complaints.     

Brainstem auditory evoked potentials in children with lead exposure

IntroductionEarlier studies have demonstrated an auditory effect of lead exposure in children, but information on the effects of low chronic exposures needs to be further elucidated.ObjectiveTo investigate the effect of low chronic exposures of the auditory system in children with a history of low blood lead levels, using an auditory electrophysiological test.MethodsContemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6 years, 8 months ± 3 years, 2 months).ResultsThe mean time-integrated cumulative blood lead index was 12 μg/dL (SD ± 5.7, range: 2.433). All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I–III, III–V, and I–V, and the cumulative lead values.ConclusionNo evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area.     

等调制深度时间调制转换曲线评估豚鼠下丘和听皮层的时间分辨率

目的探讨以听觉系统对调幅信号响应幅值随调制频率的改变计算等调制深度时间调制转换函数（temporal modulation transfer function，TMTF）来客观评估听觉系统时间分辨率的可行性。方法豚鼠下丘和听皮层分别埋植慢性电极，记录正弦调幅纯音（载频为8kHz，调制深度固定为100％）诱发电位，反应幅值经快速傅立叶变换（fast Fourier transform，F丌）得出相对反应幅值，并以相对反应幅值和调制频率绘制出等调制深度TMTF。记录正弦调幅纯音每个调制频率的调制深度从100％至10％的诱发电位，得出与传统的调制深度阈值TMTF方法相当的等幅值TMTF，与等调制深度TMTF相比较，判断等调制深度TMTF方法的有效性。结果豚鼠下丘和听皮层的等调制深度TMTF与等幅值TMTF都分别表现为带通和低通特性；等调制深度TMTF的截止频率与等幅值TMTF的截止频率差异无统计学意义（P值均〉0．05）。豚鼠听皮层等调制深度TMTF的截止频率与传统的行为学结果基本一致。结论以100％调制深度的正弦调幅纯音诱发反应幅值与调制频率绘制等调制深度TMTF是一种有效的客观评估听觉系统时间分辨率的方法，其中豚鼠听皮层的等调制深度TMTF可用于行为学预测。     

全身麻醉对小儿听性脑干反应测试结果的影响

目的　研究应用听性脑干反应 (auditorybrainstemreaction ,ABR)作为监测小儿全身麻醉深度与觉醒的客观指标。方法　选择听力正常的外科择期手术患儿 4 5例 ,按照美国麻醉学家学会表针分为Ⅰ～Ⅱ级 ,分别施行异丙酚静脉麻醉、芬太尼静脉麻醉及异氟醚吸入全身麻醉 ,随机每组 15例 ,应用丹麦Madsen诱发电位反应仪监测并记录麻醉各阶段ABR的Ⅰ、Ⅲ、Ⅴ波潜伏期及Ⅰ Ⅲ、Ⅲ Ⅴ、Ⅰ Ⅴ波间期 ,研究观察潜伏期和波间期随时间推移及麻醉剂量变化之间的关系 ,探讨ABR在异丙酚、芬太尼及异氟醚等不同麻醉中的表现特征和规律。结果　①异丙酚静脉麻醉和异氟醚吸入麻醉与剂量呈良好的正相关 ;②Ⅰ波的潜伏期特性对于控制麻醉深度极为重要 ;③Ⅴ波监测麻醉具有最佳的稳定性及相关性 ;④停用麻醉药一段时间或患儿基本清醒时 ,ABR各波潜伏期和波间期有的仍高于正常值 ,这是滞后 (延迟 )反应 ;⑤ABR对芬太尼术中的觉醒监测不太敏感。结论　ABR各波的潜伏期及波间期变化 ,可判断小儿全身麻醉深度 ,在一定程度上可作为判断觉醒的参考 ,但应考虑有延迟反应的可能     

Central auditory processing: behavioral and electrophysiological assessment of children and adolescents diagnosed with stroke

IntroductionCentral auditory processing refers to the efficiency and effectiveness with which the central nervous system uses auditory information: it may be altered in neurological disorders and brain injuries, such as strokes. However, despite evidence of probable alterations in the pediatric population, functional abilities and post-stroke limitations are still not well documented in the literature.ObjectiveTo analyze the findings of the electrophysiological and behavioral evaluations of central auditory processing of children and adolescents diagnosed with stroke from a reference outpatient clinic, as well as to investigate possible associations with the variables: type and location of the stroke and age group.MethodsThe present study is characterized as comparative cross-sectional. The sample, for convenience, included individuals aged 7–18 years divided into two groups: study group, composed of individuals with a diagnosis of stroke, and control group, composed of individuals with typical development. The evaluation consisted of the following procedures: anamnesis, basic audiological evaluation, behavioral evaluation of the auditory processing disorder (dichotic digit test, dichotic consonant-vowel, synthetic sentence identification/pediatric speech intelligibility, gaps in noise, pitch pattern sequence, masking level difference), and electrophysiological evaluation (P300 and mismatch negativity).ResultsNineteen children and adolescents were included in the study group. The control group was composed of 19 children and adolescents with typical development. In the comparison between the groups, a worse performance is observed for the study group in all the evaluated tests, behavioral and electrophysiological. In the behavioral evaluation of central auditory processing, there was a statistical difference for all tests, except for masking level difference and dichotic digit test, binaural separation step on the left. In the electrophysiological evaluation, there was a statistical difference in the latency of mismatch negativity and P300. No associations were found between the behavioral and electrophysiological findings and the location of the stroke and age group variables.ConclusionChildren and adolescents diagnosed with stroke present a worse performance in the electrophysiological and behavioral evaluations of central auditory processing when compared to a control group.     

Effect of hearing aids use on speech stimulus decoding through speech-evoked ABR

Introduction

The electrophysiological responses obtained with the complex auditory brainstem response (cABR) provide objective measures of subcortical processing of speech and other complex stimuli. The cABR has also been used to verify the plasticity in the auditory pathway in the subcortical regions.

儿童OSAHS不同刺激重复率听性脑干反应的临床研究

目的 探讨儿童阻塞性睡眠呼吸暂停低通气综合征(obstructive sleep Apnea-hypopnea syndrome,OSAHS)的脑干听觉诱发电位反应(Brain Auditory Evoked Potention,BAEP)的特征。方法 对经多导睡眠检测确诊的儿童OSAHS患者87例,经声阻抗检查呈A型曲线,4～7岁,分别以11.1、33.1?Hz的不同刺激重复率进行BAEP测试,比较不同病变程度对两种刺激重复率听觉阈值、潜伏期及波间期差的影响。结果 与对照组比较,OSAHS轻度组：两种刺激重复率的 BAEPⅠ、Ⅲ、Ⅴ波的潜伏期及波间期差均在正常范围,Ⅴ波听阈为25dBnHL;中度组：刺激重复率33.1Hz,Ⅰ、Ⅲ、Ⅴ波的潜伏期及波间期差无异常,Ⅴ波听阈25dBnHL;刺激重复率11.1Hz,Ⅰ、Ⅲ、Ⅴ波的潜伏期延长,差异具有统计学意义（P＜0.05）,Ⅰ～Ⅲ、Ⅰ～Ⅴ波间期延长,Ⅲ～Ⅴ间期在正常范围,Ⅴ波听阈28dBnHL;重度组：刺激重复率33.1Hz,Ⅰ、Ⅲ、Ⅴ波的潜伏期及各波间期差均延长,Ⅴ波听阈35dBnHL;刺激重复率11.1Hz,Ⅰ、Ⅲ、Ⅴ波的潜伏期及波间期差均延长,Ⅴ波听阈40dBnHL。重度OSAHS患者两种刺激重复率各波潜伏期、波间期差听阈改变均具有统计学意义。结论 低频短声刺激能较早反映OSAHS患儿脑干功能的改变;重度OSAHS患儿的BAEP测试结果异常,提示OSAHS对听阈及听觉脑干传导功能都存在影响。     

儿童chirp听性脑干反应与行为测听的相关性

目的 采用chirp信号作为声刺激进行听性脑干反应(ABR)测试,观察chirp ABR阈值与行为测听的相关性,探讨chirp ABR作为儿童临床客观听力评估的可行性.方法 选择2007年8月至9月佛山市听觉语言康复中心的听力障碍儿童和广州市儿童医院听力门诊的正常听力儿童共22例(共35耳)作为研究对象,分别进行行为测听和chirp ABR测试,并对chirp ABR反应阈和行为测听阈值进行Pearson相关性分析.结果 22例接受测试儿童中男14例,女8例,年龄3.3～6.5岁,平均年龄4.8岁.纳入研究的35耳中,正常听力6耳,听力损失轻度2耳、中度4耳、重度10耳、极重度13耳.行为测听0.5、1、2、4 kHz平均听阈与chirp ABR阈值,0.5 kHz听阈与L-chirp ABR阈值,1～4kHz平均听阈与U-chirp ABR阈值之间的相关系数分别为0.939,0.900及0.930,P值均<0.05.结论 chirp ABR作为一种客观测听技术,能够较好地反映儿童的听力水平,有希望应用到临床工作中.     

Evaluation of peripheral auditory pathways and brainstem in obstructive sleep apnea

Introduction

Obstructive sleep apnea causes changes in normal sleep architecture, fragmenting it chronically with intermittent hypoxia, leading to serious health consequences in the long term. It is believed that the occurrence of respiratory events during sleep, such as apnea and hypopnea, can impair the transmission of nerve impulses along the auditory pathway that are highly dependent on the supply of oxygen. However, this association is not well established in the literature.

早产低出生体重儿听觉功能评估及临床特征分析

目的 本研究对孕龄＜37周的早产儿,按其不同的出生体重进行分组,对其听力状况进行动态观察和分析,探讨早产低出生体重儿的听力异常状况及婴幼儿早期听觉功能发育的规律.方法 选取2004年1月至2008年2月孕龄＜37周并进行听力评估者,共252例(504耳).根据入选早产儿的出生体重大小分为:出生体重≤1.50 kg、1.51～2.00 kg、2.01～2.50 kg以及＞2.50 kg四组.每个出生体重组又根据受试者首次接受听力评估时的月龄大小,分为0～3月龄(包含3个月)、3～6月龄(包含6个月)和＞6月龄三个亚组;对于同一研究对象在不同月龄时曾接受多次听力评估者,再设多次评估亚组.所有患儿均进行一项或是多项客观听力检测,包括听性脑干反应(ABR)、畸变产物耳声发射(DPOAE)、鼓室声导抗和镫骨肌声反射.结果 随着早产儿出生体重的增加,ABR波V阈值存在降低的趋势,ABR波V阈值(正常听力级)≤40 dB耳的比例也逐渐增加.随着早产儿出生后月龄的增加,ABR波V阈值也存在降低的趋势,ABR波V阈值≤40 dB耳的比例逐渐增加.多次评估组中,各出生体重组的ABR总好转率,最低者为56.67%;出生体重≤1.50 kg组耳重复评估间隔时间＜2月的ABR好转率,明显高于出生体重1.51～2.00 kg组和2.01～2.50 kg组;1.51～2.00 kg组重复评估间隔时间＜2月时,测试耳ABR的好转率明显低于间隔时间为2～3月和＞3月的好转率.有4例6耳ABR表现为最大强度刺激声(正常听力级103 dB)无波分化或仅见波V,而DPOAE各频点幅值却均在正常范围内,初步诊断为听神经病,其发生率为3.75%(6耳/160耳).结论 早产低出生体重儿的听觉功能(包括中耳及听觉神经系统),随出生体重及出生后月龄的增加,在一定时段存在逐渐发育完善的现象.对于听力评估异常的早产低出生体重儿,应建立超过6个月以上的随访制度.出生体重≤1.50 kg初次听力评估异常者,重复评估间隔时间不超过2个月为宜,出生体重＞1.50 kg初次听力评估异常者,重复评估间隔时间以不超过3个月为宜.     

小儿蜗后听觉神经损害的临床与听力学特征及定位

目的 探讨包含了听神经病在内的ABR严重异常、DPOAE正常为特征的蜗后听觉神经功能障碍小儿的临床与听力学特征及其可能的病损部位.方法 选取2002至2006年听力专科中ABR严重异常、DPOAE正常,排除中耳传导功能异常的患儿86例(165耳),年龄8 d～7岁,平均1岁1个月,入选为本研究对象.选择ABR严重异常、DPOAE异常、排除中耳病变的听功能障碍26例(29耳)患儿作为蜗性病变对照组,选择健康同龄儿童86例(166耳)作为正常对照组,比较蜗后病变、蜗性病变、正常听力3组间ABR波Ⅰ、波Ⅲ、波Ⅴ潜伏期和振幅,以及Ⅰ～Ⅲ波间期等参数的异同.所有数据采用SPSS11.0统计软件包进行t检验.结果 86例蜗后听神经损害患儿中,51例(59.3%)的病例新生儿期有高胆红素血症史,其中40例血中间接胆红素水平达重度标准,11例为轻中度;在首次就诊的原因中,主诉运动障碍者40例(46.5%),听力言语障碍者10例(11.6%);在伴随的疾病中,32例(37.2%)确诊伴随有脑性瘫痪.在86例165耳蜗后听觉神经功能障碍患耳中,103耳最大强度声刺激(103 dB)ABR无波分化,27耳仅见波Ⅰ分化,19耳仅见波Ⅴ分化,13耳见波Ⅰ+Ⅲ分化,3耳见波Ⅰ+Ⅴ分化.仅见波Ⅰ分化耳,其波Ⅰ潜伏期较正常听力耳延长,振幅较正常听力耳低矮(t值分别为-6.75和2.58,P值均<0.05);有波Ⅰ+Ⅲ分化耳,波Ⅰ潜伏期和振幅与正常听力耳差异无统计学意义,波Ⅲ潜伏期则较正常听力耳延长,振幅较正常听力耳低矮(t值分别为-2.77和3.63,P值均<0.05),Ⅰ～Ⅲ波间期较正常听力耳Ⅰ～Ⅲ波间期延长(t=-2.99,P<0.05).结论 在蜗后听觉神经功能损害类型中,最常见的类型为ABR从波Ⅰ开始就严重异常,即听神经病,其病变主要在第Ⅷ颅神经听支;仅见波Ⅰ分化耳,其病变部位主要在第Ⅷ颅神经听支以后;ABR有波Ⅰ+波Ⅲ分化耳,主要病变部位在波Ⅲ的发源神经核团,即上橄榄核以后的听觉神经通路.振幅低矮的波Ⅴ不是听神经病独有的特征.高胆红素血症导致的蜗后听觉神经系统病变的病例中,其受侵害部位的先后次序可能为大脑皮层、腩干听觉神经核团、第Ⅷ对颅神经听支.