Relationship between the auditory brainstem response and auditory nerve thresholds in cats with hearing loss

This study explored the relationship between the auditory brainstem response (ABR) and auditory nerve sensitivity in cats with normal hearing and with noise-induced permanent threshold shifts. A statistically significant linear correlation was found between each cat's ABR thresholds and the most sensitive single neuron thresholds at the same frequency. ABR thresholds were approximately 25 dB higher than the thresholds of the most sensitive neural responses in cats with normal hearing. The two measures produced equivalent thresholds at impaired frequencies in subjects with sensorineural hearing loss. Two factors may have contributed to this convergence of ABR and neural thresholds. First, our results suggest that the elevation of the most sensitive neural responses led to a compressed threshold distribution. Consequently, only a narrow range of sound levels separated stimulus conditions that activated relatively few fibers from those that were sufficient to evoke a robust population response. In addition, the threshold responses of impaired auditory nerve fibers may have been augmented by activity in the more sensitive 'off-frequency' regions that surrounded a discrete cochlear lesion. Across varying degrees of hearing loss, the ABR maintained a systematic relationship to auditory nerve fiber thresholds, and therefore has the potential to be used as a functional assay of cochlear pathology.     

Auditory brainstem response results as predictors of behavioral auditory thresholds in severe and profound hearing impairment

Pediatric cochlear implantation is restricted to patients with stable, bilateral profound sensorineural hearing losses who derive no benefit from conventional amplification. Obtaining reliable audiologic thresholds in a young child with sudden or early-onset hearing loss can be challenging. This study examines the accuracy with which auditory brainstem response evaluation can predict unaided and aided behavioral thresholds in a child with severe-to-profound hearing loss. Reliable behavioral thresholds were obtained on 119 children who had no measurable click-evoked auditory brainstem responses at instrumentation limits of 100 dB HLn. These data show that an absent auditory brainstem response at 100 dB HLn does not necessarily indicate the absence of measurable unaided hearing for test frequencies ranging from 250 Hz to 4000 Hz. Average aided thresholds of better than 60 dB were present in 43% of the children for 500, 1000, and 2000 Hz and in 53% for 500 and 1000 Hz. Therefore, the absence of a click-evoked auditory brainstem response at 100 dB HLn in a young child is not prima facie evidence of the child's cochlear implant candidacy.     

Auditory steady-state response and auditory brainstem response thresholds in children

The inclusion of the auditory steady-state response (ASSR) into test-batteries for objective audiometry has allowed for clinical comparisons with the most widely used procedure, the auditory brainstem response (ABR). The current study describes ASSR and ABR thresholds for a group of infants and young children with various types and degrees of hearing loss. A sample of 48 subjects (23 female) with a mean age of 2.8 ± 1.9 years SD were assessed with a comprehensive test-battery and classified according to type and degree of hearing loss. Thresholds were determined with a broadband click-evoked ABR and single frequency ASSR evoked with continuous tones (0.25–4 kHz) amplitude modulated (67–95 Hz). Mean difference scores (±SD) between the ABR and high frequency ASSR thresholds were 9.8 (±11), 3.6 (±12) and 10.5 (±12) dB at 1, 2 and 4 kHz, respectively. An ASSR mean threshold for 2–4 and 1–4 kHz compared to the ABR threshold revealed an average difference of 7 (±9) and 7.9 (±8) dB, respectively. The overall correlation between the ABR and ASSR thresholds was highest for the mean ASSR thresholds of 2–4 and 1–4 kHz (r = 0.92 for both conditions). Correlations between the ABR and individual ASSR frequencies were slightly less (0.82–0.86). The average of the 2–4 kHz ASSR thresholds correlated best with the click-evoked ABR for all categories of hearing loss except for the sensorineural hearing loss category for which the 1–4 kHz ASSR average was better correlated to ABR thresholds. Findings demonstrate the reliability of verifying high frequency ASSR thresholds with a click-evoked ABR as an important cross-check in infants for whom behavioural audiometry may not be possible.     

Auditory brainstem responses and usefulness of hearing aids in hearing impaired children with Cornelia de Lange syndrome

OBJECTIVE: To examine auditory brainstem evoked responses (ABRs) of children with Cornelia de Lange syndrome (CDLS) to evaluate hearing and the utility of hearing aids in hearing impaired cases. SUBJECTS AND METHODS: Thirteen Japanese infants and children with CDLS were studied. Behavioral observation audiometry and ABR were used to evaluate hearing. RESULT: Four different ABR patterns at 85 dB clicks were observed: no response in either ear (6 patients); clear ABRs in both ears (2 patients); no response in one ear but ABRs recorded in the other ear (3 patients); and no peaks after wave III in one ear and ABRs recorded in the other ear (2 patients). However, in 2 patients with no response in either ear at the first measurement, ABRs were recorded in one ear within 2 years. Three out of 13 patients exhibited better responses to sound through the use of hearing aids and auditory training. CONCLUSIONS: The fitting of hearing aids and early consistent training have a significant effect on auditory development in CDLS children in terms of making them aware of sound localization and the different types of environmental sound.     

多频稳态诱发电位和听性脑干反应对感音神经性聋儿童客观听阈的评估

目的比较多频稳态诱发电位(MASSR)与短纯音听性脑干反应(Tb-ABR)对感音神经性聋儿童客观听阈的评估。方法对37名感音神经性聋儿童分别测试MASSR反应阈、Tb-ABR反应阈和行为听阈,参照行为听阈,比较MASSR反应阈和Tb ABR反应阈对行为听阈评估的准确性。结果MASSR反应阈、Tb-ABR反应阈和行为听阈之间均有较高的相关性。二者在频率为2、4kHz时,对行为听阈的评估具有相似的准确性;但在频率为0.5、1kHz时,MASSR的准确性较Tb ABR的准确性高。结论MASSR和Tb-ABR均可用作感音神经性聋儿童言语频率客观听阈的评估,但MASSR在低频(0.5、1kHz)时较Tb-ABR的准确性高。     

Auditory brainstem responses in noise-induced permanent hearing loss

Fifty-four patients (108 ears) with presumed noise-induced hearing loss, were subjected to tonal and speech audiometry, impedance tests and measurements of auditory brainstem responses (ABR), in order to check for possible retrocochlear involvement. ABR data indicated that latency values of waves I, III and V, as well as III-I, V-III and V-I intervals fell within the normal range in all cases (M +/- 2 SD), even for fast repetition rates (51 stim/s). Poor waveform resolution of early components, particularly of wave I, was found in 12 ears (11.1%) and a total absence of evoked potentials not always related to the hearing loss, occurred in 5 ears (4.6%).     

2035例婴儿听性脑干反应与多频稳态反应阈值的比较

目的 探讨婴儿听性脑干反应(auditorybrainstem response,ABR)与多频稳态反应(auditorysteady-state response,ASSR)的关系.方法 对2035例婴儿进行ABR和ASSR检测,结果采用SPSS 17.0进行相关分析、t检验和直线回归分析.结果 ①ABR反应阈与ASSR不同频率反应阈值的相关系数为0.732～0.915 (P＜0.05).②在t检验中,ABR反应阈值与ASSR 4 kHz反应阈值差异无统计学意义(P＞0.05),其余比较差异均有意义(P＜0.05).③ABR预测ASSR0.5、1、2、4 kHz、高频均值、均值的回归方程分别为:y=0.979x-6.921,y=0.909x-1.705,y=0.948x-3.647,y=1.117x-5.113,y=1.033x-4.380,y=0.988x-4.346.结论 婴儿ABR与ASSR反应阈值具有较好的相关性,其主要是反映ASSR 4 kHz的反应阈值.     

Frequency-specific auditory brainstem responses. Effective masking levels and relationship to behavioural thresholds in normal hearing adults

Ipsilateral masking levels and normal thresholds for tone pip auditory brainstem responses (ABRs) were investigated in normal subjects for the purpose of establishing recording parameters and norms for frequency-specific tone pip ABR testing. White noise was found to effectively mask ABRs to tone pips at mean signal-to-noise ratios of between -1 and -5.5 dB [dB peak-equivalent (pe) SPL/dB SPL] depending on the tone pip frequency. ABR thresholds were established for tone pips in the presence of ipsilateral masking with high-pass filtered noise for 50-Hz tone pips and notched noise for tone pips from 1,000 to 4,000 Hz, at a nominal signal-to-noise ratio of -5 dB (i.e. with the noise SPL measured prior to filtering). Thresholds occurred between 28.6 and 36.6 dB pe SPL, equivalent to 4.4-8.8 dB nHL. ABR thresholds for masked and unmasked tone pips did not differ significantly.     

Auditory brainstem responses to tone bursts in normally hearing subjects

Auditory brainstem responses were recorded from 20 normally hearing subjects using tone-burst stimuli that were gated with cosine-squared functions. Clear responses were observed over a wide range of frequencies and levels. These responses were highly reproducible within individual subjects and were reliably measured by two independent examiners. ABR thresholds were higher than behavioral thresholds for all frequencies, especially for lower frequencies. Intersubject variability also was greater for lower frequencies. Wave-V latencies decreased with increases in both frequency and level for frequencies from 250 to 8000 Hz and for levels from 20 to 100 dB SPL. The standard deviations seldom exceeded 10% of the mean wave-V latency for any combination of level and frequency. These latencies can be viewed as the sum of both a peripheral and a central component. Assuming that the central component is relatively independent of both frequency and level, changes of wave V latency must be related to peripheral factors, such as travel time along the cochlear partition, and to stimulus characteristics, such as rise time.     

Single auditory nerve fiber and action potential latencies in normal and noise-treated chinchillas

Latency-intensity functions for the auditory nerve action potential (AP) and single auditory nerve fibers were measured in a group of normal and a group of noise-treated chinchillas using click stimuli. The noise-treated group was exposed for 5 days to an octave band of noise centered at 0.5 kHz and having an SPL of 95 dB. The AP visual detection level (VDL) and the single neuron thresholds were approximately 40–50 dB higher in the noise-treated group than in normals. At the VDL, the latency for AP was shorter in the noise-treated group than in the normal group; however, for the same intensity the latency was the same for both groups. Similar results were obtained from single fibers of similar characteristics frequency (CF). At threshold, the fiber latencies were shorter for the noise-treated group than for normal animals, but at the same intensity, the latencies for the two groups were similar. The results indicate that AP and single fiber latencies are a function of absolute intensity rather than intensity relative to a ‘neural threshold’. A comparison of poststimulus time (PST) histograms made at the same intensity revealed fewer peaks in the units from noise-treated animals than in normal units; however, the width of the peaks and the time between peaks appeared normal.     

Auditory brainstem responses in a case of high-frequency conductive hearing loss

Click-evoked auditory brainstem responses were measured in a patient with high-frequency conductive hearing loss. As is typical in cases of conductive hearing loss, Wave I latency was prolonged beyond normal limits. Interpeak latency differences were just below the lower limits of the normal range. The Wave V latency-intensity function, however, was abnormally steep. This pattern is explained by the hypothesis that the slope of the latency-intensity function is determined principally by the configuration of the hearing loss. In cases of high-frequency hearing loss (regardless of the etiology), the response may be dominated by more apical regions of the cochlea at lower intensities and thus have a longer latency.     

Frequency-specific auditory brainstem responses relationship to behavioural thresholds in cochlear-impaired adults

Auditory brainstem response (ABR) thresholds to ipsilaterally masked tone pip stimuli were obtained from three groups of hearing-impaired subjects. Using high-pass (for 500-Hz tone pips) and notched noise (for 1-, 2- and 4-kHz tone pips), ABR thresholds in subjects with low-frequency, high-frequency or flat cochlear hearing losses were compared to conventional pure-tone audiometric thresholds. A strong positive relationship was found between ABR and behavioural threshold elevation. Absolute ABR thresholds at 500 Hz were significantly higher than those at other frequencies. The results of this study indicate that frequency-specific ABR testing can provide an approximation of both degree and configuration of cochlear hearing losses in adults. Further refinements of testing and judging procedures are needed however to reduce the variation evident in our results and thus achieve the accuracy required for most clinical applications.     

Newborn hearing screening with combined otoacoustic emissions and auditory brainstem responses

Accurate assessment of neonatal hearing screening performance is impossible without knowledge of the true status of hearing, a prohibitive requirement that necessitates a complete diagnostic evaluation on all babies screened. The purpose of this study was to circumvent this limitation by integrating two types of screening measures obtained near simultaneously on every baby. Peripheral auditory function was defined by otoacoustic emission results. A complete diagnostic evaluation was performed on every baby who received a "Refer" outcome for auditory brainstem response screening. The integrated results for auditory brainstem response screening in an unselected group of 300 newborns estimated sensitivity at 100%, specificity at 99.7%, overall referral rate at 2.0%, and a positive predictive value of 83.3%. Conductive loss associated with amniotic fluid in the middle ear can persist several weeks after birth; conductive loss can produce a "Refer" outcome for auditory brainstem response screening; and auditory neuropathy can be detected with screening measures. Prevalence results were consistent with the published literature. The implications of this study are that otoacoustic emissions and auditory brainstem measures provide much more information than either alone and that both are needed for a comprehensive hearing screening program.     

Auditory brainstem responses are impaired in EphA4 and ephrin-B2 deficient mice

The Eph receptor tyrosine kinases and their membrane-anchored ligands, ephrins, are signaling proteins that act as axon guidance molecules during chick auditory brainstem development. We recently showed that Eph proteins also affect patterns of neural activation in the mammalian brainstem. However, functional deficits in the brainstems of mutant mice have not been assessed physiologically. The present study characterizes neural activation in Eph protein deficient mice in the auditory brainstem response (ABR). We recorded the ABR of EphA4 and ephrin-B2 mutant mice, aged postnatal day 18-20, and compared them to wild type controls. The peripheral hearing threshold of EphA4(-/-) mice was 75% higher than that of controls. Waveform amplitudes of peak 1 (P1) were 54% lower in EphA4(-/-) mice than in controls. The peripheral hearing thresholds in ephrin-B2(lacZ/)(+) mice were also elevated, with a mean value 20% higher than that of controls. These ephrin-B2(lacZ/)(+) mice showed a 38% smaller P1 amplitude. Significant differences in latency to waveform peaks were also observed. These elevated thresholds and reduced peak amplitudes provide evidence for hearing deficits in both of these mutant mouse lines, and further emphasize an important role for Eph family proteins in the formation of functional auditory circuitry.     

游戏测听与听觉诱发脑干反应评估小儿听力

目的 通过对60例3～6岁感音神经性耳聋小儿听性脑干反应(auditory brainstem response,ABR)与小儿游戏测听(play audiometry,PA)测试结果比较,综合评估小儿听力.方法 选择60例3～6岁门诊患儿,均经声导抗测试及耳声发射测试排除传导性耳聋及听神经病,将60例3～6岁小儿120耳分别进行ABR测试.根据ABR测试结果.选择ABR波V反应阈为50～90 dB nHL的小儿30例为A组,ABR最大输出97 dB nHL未引出波V反应阚的小儿30例为B组;之后两组小儿分别进行游戏测听,将两组的ABR反应阈与游戏测听测试结果进行比较.结果 A组ABR的波V反应阈与小儿游戏测听中2 kHz～4 kHz最小听闻相差均无显著差异:B组ABR最大输出97 dB nHL未引出波V的小儿,游戏测听绝大部分均能获得行为听阈.结论 ABR的波V反应阈与小儿行为测听的高频听阈一致性较好;ABR最大输出97 dB nHL未引出波V的不等于无听力.     

Perinatal hypoxia and auditory brainstem response thresholds: no evidence of permanent hearing loss

It has been suggested that pre-natal and or peri-natal hypoxia can cause permanent hearing loss as a result of interference with the generation of the endocochlear potential, especially if this interference occurs during the critical period of endocochlear potential development. This hypothesis was tested in 4 series of experiments: in neonatal rats exposed to pure nitrogen for several minutes; in neonatal and adult cats respirated with hypoxic gas mixture for an hour; in neonatal rats and cats breathing hypoxic gas mixture for several hours; and in neonatal rats in hypobaric chamber for several days. In each experiment, the auditory nerve-brainstem evoked response threshold was elevated during hypoxia in those animals in which it could be measured but was normal when determined several hours to days later. This is evidence for a remarkable ability of the auditory system to recover from periods of hypoxia even during the critical period of endocochlear potential development.     

Comparison of auditory steady-state responses and auditory brainstem responses in audiometric assessment of adults with sensorineural hearing loss

Objective

Many of the medico-legal patients who claimed compensation may exaggerate hearing loss that varies in degree, nature, and laterality. The purpose of this study was to investigate whether Auditory Steady-State Response (ASSR) could be used to predict the hearing level of adults, and whether ASSR could become a better testing method than Auditory brainstem response (ABR) in audiometric assessment of adults with sensorineural hearing loss.

Methods

This was a prospective study, which was conducted in a tertiary referral hospital. From January to June 2007, 142 subjects (284 ears) with varying degrees of sensori-neural hearing impairment were included in this study. Four commonly used frequencies (500, 1000, 2000, 4000 Hz) were evaluated. All subjects received pure-tone audiometry, multi-channel ASSR, and ABR tests for threshold measurement. The correlation of pure tone thresholds with ASSR and ABR thresholds were assessed.

Results

Between multi-channel ASSR and pure tone thresholds, a difference of less than 15 dB was found in 71% while a difference of less than 25 dB was found in 89% of patients. The correlation coefficient (r) of multi-channel ASSR and pure tone thresholds were 0.89, 0.95, 0.96, and 0.97 at 500, 1000, 2000, and 4000 Hz, respectively. The strength of the relationship increased with increasing frequency. On the other hand, between ABR and pure-tone thresholds, a difference of less than 15 dB was found in 31%; a difference of less than 25 dB was found in 62% of patients. The r correlation value for ABR and pure tone thresholds was 0.83.

Conclusion

ASSR is a more reliable test for the accurate prediction of auditory thresholds than ABR. It can be a powerful and convenient electro-physiologic examination tool for clinically assessing of adults with sensorineural hearing loss.     

Using multi-stimulus auditory steady state response to predict hearing thresholds in high-risk infants

The purpose of this study was to investigate whether multi-stimulus auditory steady-state responses were capable of estimating hearing thresholds in high-risk infants. A retrospective chart review study. Three tertiary referral centers. Infants born between January 2004 and December 2006 who met the criteria for risk factors of congenital hearing loss were enrolled in the study. While under sedation, the multi-stimulus auditory steady-state response was used to determine multi-channel auditory steady-state response thresholds for high-risk infants younger than 13 months. Conditioned play audiometry was then applied to these children at 23–48 months of age to obtain pure tone audiograms. Auditory steady-state response thresholds and pure tone thresholds were then compared. A total of 249 high-risk infants were enrolled in the study. 39 infants were lost during follow-up. The remaining 216 infants completed both examinations. The Pearson correlation coefficients (r) between the ASSR levels and pure tone thresholds were 0.88, 0.94, 0.94 and 0.97 at 500, 1,000, 2,000 and 4,000 Hz, respectively. The strength of the relationship between the auditory steady-state responses and pure tone thresholds increased with more severe degrees of hearing loss and higher frequencies. We conclude that initial multichannel ASSR thresholds measured under sedation are highly correlated with pure tone thresholds obtained 2 or 3 years later. ASSR can be used to predict the frequency-specific hearing thresholds of high-risk infants and can provide information for early hearing intervention.