Audiometric estimation error with the ABR in high risk infants

Click ABR wave V thresholds in the first year were compared with follow-up behavioural pure-tone audiometry under earphones at age 3 to 6 years in 713 infants (yielding 1,367 ears) at risk for hearing loss. The observed accuracy of the ABR depends strongly on the precise definitions of the target disorder and the test abnormality criteria. For sensorineural hearing loss of more than 20 dB averaged at 2 kHz and 4 kHz, the click ABR provides an accurate test, with both false positive and false negative rates of less than 10%, using an ABR threshold criterion of 30 dB nHL. The false positive error rate can be at least halved by using a simple rule for wave V latency that discriminates conductive and sensorineural ABR threshold abnormalities. False negative errors may be explicable in terms of the lack of frequency specificity of the click stimulus.     

ABR hearing screening for high-risk infants.

OBJECTIVE: The goals of this investigation were to determine the outcome of a high-risk newborn auditory brainstem response hearing screening program at this institution and to determine the clinical characteristics of the target population with special emphasis on the relationship between risk criteria and hearing status. STUDY DESIGN: This study involved the prospective screening of newborns with risk indicators and a retrospective analysis of results accumulated over a 10-year period. SETTING: The study was conducted either in the newborn nursery or outpatient audiology clinic of a tertiary health care center. PATIENTS: Patients were 2,103 newborns presenting with one or more risk indicators for significant congenital hearing loss or delayed onset/progressive sensorineural hearing loss. INTERVENTIONS: Diagnostic interventions involved auditory brainstem response screening at two intensity levels (25 dB and 65 to 75 dBnHL). MAIN OUTCOME MEASURES: The main outcome measure was incidence of significant, nonmedically treatable hearing loss in this population. A secondary outcome measure was determination of incidence of hearing loss in association with different risk indicators. RESULTS: One hundred fourteen (5.4%) infants were diagnosed with bilateral hearing loss. Twenty-three infants (1%) presented with unilateral hearing loss. Sixty seven (49%) of the 137 infants diagnosed with hearing loss presented with greater than moderate hearing loss. Nine (13.4%) of these 67 patients presented with delayed onset hearing loss that was diagnosed at appointments subsequent to the initial screening. The largest percentage of diagnosed hearing loss was found in the "craniofacial anomalies" category. CONCLUSIONS: Auditory brainstem response hearing screening of newborns at risk for significant hearing loss is a clinically efficient and cost effective approach to early detection of significant hearing loss. For this program, the calculated cost to diagnose one hearing impaired infant from this population is $3000.     

ABR thresholds in infants born with CLP and OME and infants with OME

ObjectivesThe aim of this study was to investigate and compare auditory brainstem response (ABR) thresholds related to otitis media with effusion (OME) in infants with and without cleft palate and/or lip (CP ± L).MethodsForty-seven infants with CP ± L and 67 infants with OME participated in the study. Hearing thresholds of ears of infants with OME were compared between groups and within the group with CP ± L.ResultsInfants with CP ± L and OME presented with similar hearing thresholds as infants with OME and not CP ± L. Within the cleft group, infants with isolated cleft palate and OME demonstrated significantly higher hearing thresholds than infants with unilateral cleft lip and palate and OME.ConclusionA high prevalence of infants with CP ± L present with OME early in life. Hearing thresholds of these infants are similar to infants without CP ± L, but with OME. The ear status and hearing thresholds of infants with CP ± L needs to be monitored to be able to provide the best access to hearing in order to fully allow speech and language development.     

Electrophysiologic assessment of auditory pathways in high risk infants

This study evaluated auditory processing in a group of 59 infants at risk for subsequent hearing and language disorders due to low birthweight and/or perinatal asphyxia. Auditory system integrity was evaluated electrophysiologically by recording the auditory brainstem response (ABR), middle latency response (MLR) and the cortical auditory evoked potential (CAEP). 63% of the babies had normal peripheral function or slight unilateral impairment; 84% had normal brainstem auditory system function; 82% showed normal MLRs; and 81% showed normal CAEPs. Fifty-three percent of the babies were normal on all tests and only 3% were deviant on all tests. The remaining infants showed diverse patterns of peripheral, brainstem and cortical abnormalities.     

Risk factors for elevation of ABR threshold in NICU-treated infants

Objective

Several risk factors for hearing impairment among infants treated in the neonatal intensive care unit (NICU) have been reported, but there have been few studies that show the correlation strength between the risk factors in NICU-treated infants and hearing impairment in childhood. The aim of this study was to clarify the relationship between risk factors in NICU-treated infants and a deteriolation of auditory brainstem response (ABR) threshold in their childhood.

Methods

One hundred one NICU-treated infants with ABR threshold of 50 dBnHL or more underwent 2nd ABR test at 20 months after delivery. Multiple regression analysis was performed with ABR threshold change as an objective variable and risk factors as explanatory variables.

Results

Two ABR tests of the 101 infants resulted in that 7 showed an elevation of ABR threshold by 20 dB, 70 showed a drop of ABR threshold by 20 dB, and 24 showed no significant change. Multiple regression analysis revealed that the factors contributing to the elevation of ABR threshold were congenital diaphragmatic hernia, severe respiratory disease, and a high C-reactive protein (CRP) level.

Conclusions

In the infants treated in NICU, an incidence of ABR threshold of 50 dBnHL or more was 9.0%, and 6.9% of the infants with the ABR threshold abnormality showed a significant elevation of ABR threshold in their childhood. Factors significantly related to an elevation of ABR threshold were a history of congenital diaphragmatic hernia, severe respiratory disease, and elevation of CRP. In infants with such factors, periodical examination of hearing is required.     

ABR latency in infants: properties and applications of various measures

ABR latency ratios have been proposed as useful clinical tools in the assessment of infants at risk for auditory or neurologic deficits. These parameters, together with classical absolute and interwave latency measures, were examined in 131 infants with normal ABR thresholds at 48-64 weeks post-conceptional age, and with no conventional risk factor for hearing impairment or neurological abnormality. Latency of wave I is unaffected by age or gender, but that of waves III and V decreases linearly with age and is smaller in females. These effects must be accounted for in clinical evaluation. However, latency ratios V/I, V/III and III/I show no significant age or gender effects. Wave I latency and the V/I latency ratio both permitted very good discrimination between normal infants and those with presumed conductive hearing losses, but the effects of sensorineural impairment have yet to be determined. On a priori grounds it seems improbable that latency ratios will outperform classical ABR parameters, at least for the goals and age range considered in this study.     

耳声发射异常听性脑干反应正常的婴幼儿听力学分析

目的 探讨听力筛查异常而听性脑干反应(auditory brainstem response,ABR)正常的婴幼儿的听力学特点.方法 以瞬态声诱发性耳声发射听力筛查未通过而ABR正常的新生儿及婴幼儿53例(81耳)作为研究对象,对比各项听力检查结果,分析ABR与其他检查(40 Hz听觉相关电位、听觉稳态诱发反应、畸变产物耳声发射、鼓室声导抗及声反射)之间的相互关系.结果 81耳中所有检查结果均正常18耳(22.2%);其中至少有一项检查异常共63耳(77.8%).40Hz听觉相关电位和听觉稳态诱发反应分别测试36耳和45耳,异常分别为14耳(38.9%)和27耳(60.0%);畸变产物耳声发射测试68耳,异常50耳(73.5%);鼓室声导抗测试50耳,异常9耳(18.0%);声反射测试47耳,异常27耳(57.4%).结论 单纯以ABR作为婴幼儿听力正常的判断标准尚存在不足,综合的听力学评估非常有必要.     

Predictive value of ABR in infants and children with moderate to profound hearing impairment

Click and 500 Hz tone pip ABR thresholds obtained in infancy were compared to pure-tone thresholds in 25 preschool-aged patients with moderate to profound hearing impairments. The electrophysiologic thresholds obtained in infancy were generally lower than the recent audiometric thresholds. Clicks best predicted the lowest pure-tone threshold within the 1 to 8 kHz range. The 500 Hz tone-pip thresholds were closest to the lowest of 250 Hz and 500 Hz pure-tone thresholds. Regression analyses involving audiometric and electrophysiologic thresholds and 95% confidence intervals of the differences between their means provide a basis for behavioral threshold prediction in this patient group.     

电极位置和滤波对婴幼儿短纯音诱发听性脑干反应阈值的影响

目的比较婴幼儿记录电极置于颅顶、滤波为30-1500Hz(简称第一组测试参数)与记录电极置于前额发际、滤波为30-3000Hz(简称第二组测试参数)各频率短纯音听性脑干反应(Auditory Brain Stem Re-sponse,ABR)阈值之间的差别,总结两种记录参数下短纯音ABR(tone burst ABR,tb-ABR)波形特点对阈值判断的影响,选择更优化的tb-ABR测试条件。方法应用SmartEP听觉诱发电位仪(美国IHS公司)记录0-6月龄婴幼儿短声及上述两种记录参数下tb-ABR各频率反应阈,共12例(10男/2女)20耳。结果 0.5kHz、1kHz、2kHz、4kHz记录电极置于前额发际、滤波为30-3000Hz时tb-ABR反应阈比记录电极置于颅顶、滤波为30-1500Hz时tb-ABR反应阈分别高7.00±5.5、7.25±6.0、7.25±4.7、8.00±5.5dB。各频率两种记录参数下tb-ABR反应阈之间差异均有统计学意义(t值分别为5.715、5.445、6.866、6.532,P值均<0.01)。同等强度时,两种记录参数下tb-ABR各波振幅差别明显,第一组测试参数下tb-ABR各波振幅高于第二组测试参数下tb-ABR各波振幅,前者的反应曲线较后者平滑,波V更容易辨认。结论用短纯音诱发ABR评估婴幼儿听力时,记录电极置于颅顶、滤波为30-1500Hz时各频率测试时反应阈和波形均优于记录电极置于前额发际、滤波为30-3000Hz,可提供更好的阈值测试结果。     

100例婴幼儿TB-ABR与CE-Chirp ASSR结果分析

目的对100例极重度感音神经性听力损失婴幼儿进行短纯音听性脑干反应(tone burst auditory brainstemresponse,tb-ABR)和CE-Chirp声诱发的听性稳态反应(auditory steady-state response,CE-Chirp ASSR)测试,对各频率反应阈的结果进行总结分析,比较两种测试方法的异同点。方法对100例极重度感音神经性听力损失婴幼儿进行短纯音ABR与CE-Chirp ASSR各频率反应阈值的测试,分别记录0.5k、1.0 k、2.0 k和4.0k Hz的反应阈值,所得数据采用SPSS 11.0统计软件进行相关性检验和χ2检验。结果短纯音ABR与CE-Chirp ASSR各频率能引出不同程度的阈值,V波引出阈值百分比主要集中在91~100d BHL,500~4000Hz波V阈值引出率之间的相关系数分别为:0.852、0.911、0.870、0.910,所有P<0.001。CE-Chirp ASSR与短纯音ABR各频率反应阈的χ2检验,P>0.05。。结论短声ABR提示极重度感音性听力损失婴幼儿,其短纯音ABR与CE-Chirp ASSR各频率均有不同程度的残余听力,短纯音ABR与CE-Chirp ASSR各频率反应阈引出率有很好的相关性,耳别间也无显著性差异。     

Application of conscious sedation in infants undergoing the auditory brainstem responses (ABR) examination

Results of ABR examination in infants undergone the hearing screening examinations were presented. Since February 2004 the group of 184 children were examined. In 29 of them (15.8%) there was a need of further hearing examination using evoked auditory brainstem responses. In 20 of them the examination was done in sleep induced by 6% chloral hydrate enema. The process of sleep was normal and no disturbances of breathing or circulatory systems were observed. The obtained responses from brainstem were not interfered by any artifacts and basic waves were legible and easy for interpretation. Correct results of the ABR examination were obtained in 21/29 (72%) children, while in 7/28 (24%) various degree of hearing losses were detected. Those children were referred for hearing rehabilitation to the Third Degree of Reference Center. It was emphasized in the study that results of ABR examination after conscious sedation induced by 6% chloral hydrate enema accounted the suggestion for its wider use in other clinical and hospital center.     

Click-evoked ABR at high stimulus repetition rates for neonatal hearing screening

A new, fast screening algorithm based on auditory brainstem response (ABR) recorded at a high click repetition rate is proposed. Response detection is carried out in the frequency domain by a statistical test procedure which includes the fundamental frequency and the harmonics below 800 Hz. First, the method was tested in 25 young adults. ABRs were recorded in the repetition rate range 20/s to 400/s. With a mean response detection time of 31 s, a click repetition rate of 140/s was found to be the optimum rate among the adult group. The method was then tested using a group of 114 neonates in whom the repetition rate range 60/s to 200/s was examined. At the repetition rate 90/s, which was found to be the optimum rate in neonates, the mean detection time was 24.6 s. In addition to the fast ABR detection, the proposed screening algorithm also allows simultaneous hearing screening of both ears using a one-channel data recording.     

Brain stem (ABR) and middle latency (MLR) auditory evoked responses in infants

We examined ABRs and MLRs for click and/or 500-Hz tone pip stimuli in infants (36-44 weeks conceptional age) admitted to the NICU and measured the threshold and detectability of those responses. We took the threshold indicators of those responses as Jewett V for ABR measurement and wave PO Nal Na2 for MLR measurement. Thresholds of MLRs for click stimuli were almost equal to those of ABRs for click stimuli. On the other hand, thresholds of MLRs for 500-Hz tone pip stimuli were slightly worse than ABRs for click stimuli, the average differences being less than 10 dB. Wave Po Nal Na2 are the best threshold indicators of MLRs in infants, but the diagnostic significance of wave Pa was questionable in our measurements.     

An evaluation of ABR audiometry for the screening and detection of hearing loss in ex-SCBU infants.

The study aimed to use auditory brainstem response (ABR) audiometry to test ex-SCBU infants born during 1986 in West Berkshire. Two hundred and forty-three babies were tested as out-patients, thus achieving a coverage rate of 86% of the target population. Mean post-conceptional age at test was 48 weeks. Whenever possible, full ABR threshold determination was performed on both ears and the mean ABR threshold was found to be 14 dB nHL. Of those babies attending, 85% showed ABRs at less than or equal to 30 dB nHL bilaterally and the remaining 15% were referred for further assessment. Approximately two-thirds of these were recalled successfully for repeat testing. The estimated prevalence rate for bilateral sensorineural hearing impairment was 1.4% with four confirmed cases. Two additional permanent unilateral hearing losses were also detected. On the basis of recorded ABR data, sensitivity, specificity and positive predictive values were estimated for click intensities which could be used for single-intensity ABR screens. It is concluded that delaying screening until the post-neonatal stage is a viable alternative to screening neonates prior to discharge from the SCBU.     

A comparison of auditory brain stem response and behavioral screening in high risk and normal newborn infants

A total of 345 newborn infants received a behavioral screening consistent with protocol adopted by the Joint Committee on Infant Hearing. Infants were divided into three groups consisting of 108 at-risk for hearing loss, 80 intensive care nursery graduates, and 157 normal control infants. Of the total, 315 newborns received auditory brain stem response (ABR) assessment. The results suggest that 4% of the high risk population had irreversible hearing loss to such a degree that amplification was warranted. Discussion focuses on the questionable use of behavioral screening in the newborn nursery and the application of ABR in a high risk population.     

ABR findings in vertebrobasilar ischemia

Auditory brainstem response (ABR) changes in the ischemic brainstem condition and the correlation between ABR and blood flow of the auditory pathway are not clear. In this study, ABR changes in two cases with brainstem ischemia are reported. In order to clarify the correlation between ABR changes and cochlear blood flow, experimental studies on guinea pigs with brain ischemia were performed. Changes of ABR in the human brainstem ischemic condition consisted of a decrease of the amplitudes of all waves and a delay in wave latencies. Even if ABR showed no response, it turned to normal when the blood flow was recovered. In the experimental study, the same changing patterns in ABR occurred in parallel with a decrease of the cochlear blood flow, and the cochlear blood flow was not zero when ABR became non-responsive. This suggests that ABR changes reflect the degree of ischemia in the auditory pathway, and that non-responsive ABR does not imply irreversible ischemic condition.