听性脑干反应与畸变产物耳声发射检测在听神经病诊断中的表现和意义

目的分析听神经病患者的听性脑干反应与畸变产物耳声发射特征,探讨该类听力学检测方法在听神经病诊断中的意义。方法回顾性研究本科确诊为听神经病的患者37例,比较分析其听性脑干反应与畸变产物耳声发射检测结果,探索其诊断意义。结果本组患者中,3例5耳（双耳病变2例,单耳病变1例）可引出V波,阈值70～90dB SPL,其余患耳ABR各波均未引出（刺激声强〉100dB SPL）。无论纯音听阈损失程度轻重如何,所有患者的DPOAE均全部引出。在各个频率点上,DPOAE的DP—gram幅值左、右耳间的差异均无统计学意义（P〉0．10）。结论听神经病的主要病变部位可能位于听神经传入通路,或伴有脑干内侧橄榄耳蜗系统的传出神经通路病变。     

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.     

Comparison of hearing screening programs between one step with transient evoked otoacoustic emissions (TEOAE) and two steps with TEOAE and automated auditory brainstem response

OBJECTIVE: To compare the efficacy between one step with transient evoked otoacoustic emissions (TEOAE) and two steps with TEOAE and automated auditory brainstem response (AABR) in a newborn hearing screening program. We investigated their differences in referral rate, the accurate identification rate of congenital hearing loss (HL), and cost effectiveness. METHOD: From November 1998 to December 2004, a total of 21,273 healthy newborns were screened for HL in Mackay Memorial Hospital, Taipei. In the periods from November 1998 to January 2004 and from February 2004 to December 2004, the screening tools used were TEOAE alone (n = 18,260) and TEOAE plus AABR (n = 3,013), respectively. RESULTS: A statistically significant decrease of referral rate was achieved in the group using TEOAE and AABR as screening tools when compared with TEOAE alone (1.8% vs. 5.8%). The accurate identification rate of congenital HL was 0.45% in TEOAE protocol and 0.3% in TEOAE and AABR protocol, which was not statistically significant. The total direct costs per screening were 10.1 U.S. dollars for the program using TEOAE alone and 8.9 U.S. dollars for the TEOAE plus AABR program. The intangible cost, however, was much higher in the earlier program because of the higher referral rate. CONCLUSION: In terms of the efficacy of a hearing screening program using the one step TEOAE and two step TEOAE and AABR programs, the later significantly decreased the referral rate from 5.8% to 1.8%. No significant difference was noted between the accurate identification rates of congenital HL. The total costs, including expenditures and intangible cost, were lower in the protocol with TEOAE plus AABR.     

An objective method of analyzing cochlear versus noncochlear patterns of distortion-product otoacoustic emissions in patients with acoustic neuromas

OBJECTIVES: To objectify the effects of retrocochlear disease on distortion-product otoacoustic emissions (DPOAEs) by developing a computer-based software strategy for classifying DPOAE patterns as cochlear or noncochlear and to evaluate the sensitivities of these techniques in a large series of patients with unilateral acoustic neuromas. STUDY DESIGN: Development of a novel, software-based method of DPOAE analysis, which was evaluated with data obtained from a retrospective review of the results from audiometric tests performed in a series of patients. METHODS: A computer-based software strategy was developed, using frequency-specific data from normal-hearing adults, for the purpose of distinguishing cochlear from noncochlear patterns of hearing loss, by determining the discrepancies between DPOAEs and behavioral audiometry. Preoperative pure-tone thresholds and DPOAEs from 97 patients with surgically confirmed acoustic neuroma were compared using an objective method and a standard, subjective technique that was considered to be the gold standard. The effects of bilateral hearing losses, such as noise-induced hearing loss and presbycusis, were accounted for during the analysis to isolate the effects of the tumors on hearing thresholds and DPOAEs. RESULTS: Overall, 55 (57%) of the tumor ears were assigned to the cochlear group (i.e., DPOAEs consistent with hearing thresholds), 40 (41%) to the noncochlear group (i.e., DPOAEs inconsistent with hearing thresholds), and 2 (2%) to an indeterminate group, using the subjective technique for classifying DPOAEs. There was no significant difference in the categorization of the patients with acoustic neuroma when employing the objective strategy. The objective algorithm, when modified to maximize the number of noncochlear identifications, led to assignments of 36 (37%) to the cochlear, 57 (59%) to the noncochlear, and 4 (4%) to the indeterminate categories. CONCLUSIONS: Subjective analysis of a large series patients with acoustic neuromas showed that the majority of ears with tumors demonstrated cochlear (57%), rather than non-cochlear (41%), patterns of DPOAEs. The computerized, software-based algorithm developed for differentiating cochlear from noncochlear patterns of DPOAEs in patients with retrocochlear disease had a maximum sensitivity of 59%. This value was significantly higher than that reported in previous studies.     

Evoked otoacoustic emissions and auditory brainstem responses: concordance in hearing screening among high-risk children

Objective Evoked otoacoustic emissions (OAEs) and diagnostic auditory brainstem responses (ABRs) were determined in 379 high-risk children referred for hearing screening.

Material and Methods This was a retrospective, cross-sectional study. The records of 379 children referred for hearing screening between January 2002 and March 2003 at the Ear Unit of the Philippine General Hospital were evaluated.

Results Of the 379 children, 53.6% were male and 46.4% were female and the mean age was 41±47 months. The age distribution was as follows: ≤12 months, 32.2%; 12–24 months, 52.2%; and>24 months, 11%. Out of 229 right and 232 left ears, 111 (48.5%) and 112 (48.3%) had “pass” responses and 113 (49.3%) and 116 (50.5%) had “refer” responses, respectively. Five right and four left ears had “noise” responses. Out of 266 right and 209 left ears, the ABR results showed 72 (27.1%) and 30 (14.4%) with normal auditory pathways and 194 (72.9%) and 179 (85.6%) with abnormal auditory pathways, respectively. Of the 131 children whose parents gave their consent for concomitant OAE and ABR testing, agreements were observed between the two tests in terms of classifying the results as normal or abnormal of 78.9% (κ=0.51; p=0.00) in right and 78.6% (κ=0.51; p=0.00) in left ears. When the children were classified as either “with hearing loss—bilateral abnormal ABRs” or “at least one normal ABR”, there was an observed agreement of 81% (κ=0.6; p=0.00). OAEs had a sensitivity of 76.9% (95% CI 66.7–84.8%) and a specificity of 90% (95% CI 75.4–96.7%).

Conclusion There is good concordance between OAE and ABR results among high-risk children referred for hearing screening.     

effects of glutamate on distortion-product otoacoustic emissions and auditory brainstem responses in guinea pigs

Objective To investigate changes in evoked potentials and structure of the guinea pig cochleae during whole cochlear perfusion with glutamate. Methods CM, CAP, DPOAE, and ABR were recorded as indicators of cochlear functions during whole cochlear perfusion. The morphology of the cochlea was studied via transmission electron microscopy. Results There were no significant changes in DPOAE amplitude before and after glutamate perfusion. CM I/O function remained nonlinear during perfusion. ABR latencies were delayed following glutamate perfusion. The average CAP threshold was elevated 35 dB SPL following glutamate perfusion.. The OHCs appeared normal, but the IHCs and afferent dendrites showed cytoplasmic blebs after glutamate perfusion. Conclusions While being a primary amino acid neurotransmitter at the synapses between hair cells and spiral ganglion neurons, excessive glutamate is neurotoxic and can destroy IHCs and spiral ganglion neurons. The technique used in this study can also be used to build an animal model of auditory neuropathy.     

听性脑干反应严重异常和耳声发射正常的小儿听力障碍的临床特征分析

目的　探讨包含小儿听神经病在内的听性脑干反应 (auditorybrainstemresponse ,ABR)严重异常 ,畸变产物耳声发射 (distortionproductotoacousticemission ,DPOAE)正常为特征的听功能障碍症侯群的病因学特征、病损部位与临床听力学特点。方法　选取 2 0 0 2～ 2 0 0 4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 98例 (16 8耳 )入选为研究组。根据神经康复科医师的评估 ,作出是否伴有精神运动发育迟缓及其相关病因的诊断 ,统计伴有精神运动发育迟缓的研究组中听力损失高危因素的类型与比例 ;选择ABR严重异常、DPOAE异常、排除中耳病变的患儿4 6例 (82耳 )作为蜗性病变对照组 ,比较研究组与蜗性病变患儿ABR的异同点 ;选择健康同龄小儿4 0例 (72耳 )作为正常对照组 ,观察研究组与正常听力小儿ABR和DPOAE的异同点。结果　①研究组 98例患儿中 ,83 6 7%患儿伴有精神运动发育迟缓的临床症状 ,其相关的致病因素中 ,以新生儿高胆红素血症所占的比例最高 ;② 10 3dB强度刺激声 (听力级 )刺激时 ,无波分化的为 5 3耳、仅能记录到波Ⅴ的 7耳 ,90dB强度刺激声仅能记录到Ⅴ波的 9耳 ,80dB仅能记录到Ⅴ波的 4耳 ,共 73耳(43 4 5 % ) ,病损部位主要在听神经远端 ;10 3dB强度刺激声仅能记录到波Ⅰ     

Comparison of two-step transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem response (AABR) for universal newborn hearing screening programs

OBJECTIVE: Both transitory auditory otoemissions (TEOAE) and automated auditory brainstem responses (AABR) are considered adequate methods for universal hearing screening. The goal of this study was to compare the results obtained with each device, applying the same screening procedure. MATERIALS AND METHODS: From 2001 to 2003, all the newborns in our health area (2454 infants) were evaluated with TEOAE (ILO92, otodynamics) and all those born from 2004 to 2006 (3117) were evaluated with AABR (AccuScreen, Fischer-Zoth). The population studied included all well newborns and those admitted to neonatal intensive care units (NICU). The first screening was normally undertaken with well babies during the first 48h of life, before hospital discharge. Infants referred from this first step underwent a second screening after hospital discharge, before they were a month old. RESULTS: The results from each study group were compared and analyzed for significant differences. TEOAE screening yielded 10.2% fail results from the first screening step; AABR gave 2.6%. In the second screening step, 2% of the newborns screened with TEOAE were referred, whereas 0.32% of those screened with AABR were referred. These differences are statistically significant. CONCLUSIONS: Although AABR screening tests involve a slightly higher cost in time and money than TEOAE, the results obtained compensate this difference. AABR gives fewer false positives and a lower referral rate; the percent of infants lost during follow-up is consequently smaller. Therefore, in our environment, universal newborn auditory screening with AABR is more effective than that with TEOAE.     

双侧耳蜗切除术致听力剥夺大鼠的听性脑干反应改变

目的：通过比较大鼠在双侧耳蜗切除术后不同时间点听性脑干反应（ABR）的变化,探讨ABR在测试听力剥夺大鼠模型中的应用价值。方法：选取2周龄SD大鼠40只,随机分为实验组4组（2周组、4周组、6周组、8周组）和对照组4组,每组5只（10耳）。实验组动物在双侧耳蜗损毁术后不同时间点与其对照组行ABR检测,记录ABR阈值及各波潜伏期和波间期。结果：实验组ABR反应阈明显升高,与对照组相比,差异有统计学意义（P〈0．01）,各波潜伏期和波间期明显延长（P〈0．01）;实验2周组、4周组与6周组和8周组相比,ABR反应阈的差异也有统计学意义（P〈0．01）。结论：双侧耳蜗切除术可导致大鼠ABR反应阈明显增高,各波潜伏期和波间期明显延长;听力剥夺效果从术后4周开始越发明显。     

Contralateral suppression of distortion-product otoacoustic emissions declines with age: a comparison of findings in CBA mice with human listeners

OBJECTIVES/HYPOTHESIS: The auditory efferent system plays presumed roles in enhancing signals in noise, maintaining the cochlea for optimal acoustic signal processing, and may have a protective role in preserving auditory function in the face of ototoxic events. The objective of the study was to measure age-related changes of the medial olivocochlear efferent system in mice by comparing distortion-product otoacoustic emissions generated with and without contralateral white noise stimulation. Consistent with prior work, distortion-product otoacoustic emissions were typically reduced in magnitude when white noise was presented to the contralateral ear. This contralateral suppression is attributed to activation of the medial olivocochlear efferent system, which has an inhibitory effect on the cochlear hair cell system. By studying contralateral suppression on cochlear output in subjects of different ages, it is possible to describe aging effects on the medial olivocochlear system. STUDY DESIGN: CBA mice were divided into three age groups: young adult, middle-aged, and old-aged animals (21, 13, and 22 animals per group, respectively), and auditory brainstem responses were obtained before distortion-product otoacoustic emission testing to assess overall hearing abilities. METHODS: 2f1-f2 distortion-product otoacoustic emission recordings were obtained from individual subjects (anesthetized with ketamine/xylazine) in each age group under two conditions: 1) in quiet and 2) in the presence of a contralaterally applied wideband noise. RESULTS: Principal findings were that distortion-product otoacoustic emission levels decreased with age for mice in a way similar to humans, when correcting for the absolute difference in life spans. In addition, contralateral suppression declined in middle-aged and old-aged groups relative to the young adults for mice in a manner similar to humans. The contralateral suppression decline at low frequencies preceded that of the decline in distortion-product otoacoustic emissions with age. CONCLUSION: Functional decline of the medial olivocochlear efferent system with age precedes outer hair cell degeneration. Loss of medial olivocochlear suppressive function may play a role in the development of presbycusis in both clinical cases and animal models.     

Unitary ototoxic gentamicin exposure may not disrupt the function of cochlear outer hair cells in mice

Background: Previous study showed that mild ototoxic exposure could induce a reversible hearing impairment, and the loss and secondary incomplete recovery of cochlear ribbon synapses could be responsible for the hearing loss. However, it remains unclear whether cochlear outer hair cells’ (OHCs) functions are affected.

Objective: To verify whether the function of OHCs are also affected significantly after the ototoxic exposure.

Methods: Mice were injected intraperitoneally with 100?mg/kg concentration of gentamicin daily for 14 days. Distortion Product of Oto-acoustic Emission (DPOAE) was detected at control (pre-treatment), Day 0, day 4, day 7, day 14 and day 28 after the ototoxic exposure, respectively. In addition, the morphology of OHCs was observed by electron microscopy, OHCs has been counted by light microscopy, and the hearing thresholds were detected by auditory brain response (ABR).

Results: No significant changes have been found in OHC and OHC stereocilia among the experimental groups (p?>?.05). Further, no significant changes or loss was found in the morphology of OHCs either. However, we found ABR threshold elevations occurred after ototoxic exposure.

Conclusions: Unitary ototoxic gentamicin exposure may not disrupt the function of cochlear OHCs in mice, regardless of hearing loss identified in this ototoxic exposure.     

Contralateral inhibition of distortion product otoacoustic emissions in children with auditory processing disorders

Abstract

Objective: The purpose of this study was to evaluate changes in distortion product otoacoustic emission (DPOAE) level elicited by contralateral noise in children with normal hearing, and those with auditory processing disorders (APD) whose audiometric thresholds were normal. It was hypothesized that children with APD would demonstrate smaller changes. Design: Levels of DPOAEs were recorded for f₂ stimulus tones fixed at 2, 3, and 4 kHz while the f₁ tone was ramped around nominal stimulus frequency ratios of f₂/f₁ = 1.22 and 1.10. Mean and maximum absolute changes resulting from contralateral broadband noise presented at 60 dB SPL were evaluated across the DPOAE frequency bands for each individual and for both groups of subjects. Study sample: Eight normal-hearing children and eight children with APD whose audiometric thresholds were normal participated. Results: There were no significant differences in DPOAE inhibition between normal hearing and APD groups, or previously recorded adult data. Mean absolute changes were typically near 1 dB, except for f₂ = 4 kHz and the stimulus frequency ratio 1.22 where inhibition was only 0.5 dB. However, there were individual children in both groups who demonstrated larger DPOAE changes for some stimulus parameters. Conclusions: The inhibition of otoacoustic emissions requires further study in APD children.

Sumario

Objetivo: El propósito de este estudio fue evaluar los cambios en el nivel de las emisiones otoacústicas por productos de distorsión (DPOAE) generados por ruido contralateral, en niños con audición normal y en aquellos con trastornos de procesamiento auditivo (APD), cuyos umbrales audiométricos era normales. Se planteó la hipótesis que los niños con ADP demostrarían cambios menores. Diseño: Se registraron los niveles de DPOAE para tonos de estímulo f₂ fijos a 2, 3 y 4 KHz, mientras que el f₁ fue colocado cercano a tasas nominales de frecuencia del estímulo f₁/f₂ = 1.22 y 1.10. Los cambios medios y máximos absolutos que resultaron del ruido de banda ancha contralateral a 60 dB SPL fueron evaluados en todas las bandas de frecuencias de las DPOAE para cada individuo y para ambos grupos de sujetos. Muestra del Estudio: Participaron ocho niños con audición normal y ocho niños con APD, cuyos umbrales audiométricos eran normales. Resultados: No hubo diferencias significativas en la inhibición de las DPOAE entre los grupos con audición normal y con APD, o con información de adultos previamente registrada. Los cambios medios absolutos estuvieron típicamente cerca de 1 dB, excepto para f₂ = 4 kHz, para la tasa de frecuencia del estímulo de 1.22, donde la inhibición fue solo 0.5 dB. Sin embargo, hubo niños individuales en ambos grupos que demostraron cambios mayores en DPOAE para algunos parámetros de estímulo. Conclusiones: La inhibición de las emisiones otoacústicas requiere de más estudio en niños con APD.     

DPOAE与高刺激率ABR在听力正常耳鸣患者中的应用价值

目的 观察分析听力正常的耳鸣患者畸变产物耳声发射(DPOAE)与高刺激率听性脑干反应(ABR)检测的特征,探讨其在耳鸣评估中的应用价值。 方法 选取耳鼻咽喉科门诊听力正常的青年耳鸣患者31例(46耳)为耳鸣组,另外选取听力结果正常的青年无耳鸣者25例(50耳)为正常对照组,分别进行纯音听阈测定、声导抗测听、DPOAE和高低刺激率ABR的检测,对比两组受试者DPOAE各频检出率和信噪比以及高低刺激率ABR各波潜伏期(PL)、波间期(IPL)、波幅以及两种刺激速率下的潜伏期和波间期差值(△PL和△IPL)。 结果 DPOAE各频检出率两组无显著性差异;信噪比在8 kHz,耳鸣组较对照组降低,差异有统计学意义(P<0.05);高低刺激率ABR结果中,不同刺激速率下两组Ⅰ、Ⅲ、Ⅴ波波幅差异均无统计学意义;高刺激速率下,耳鸣组Ⅰ~Ⅴ IPL较对照组延长,差异有统计学意义(P<0.05),两种刺激速率下,耳鸣组Ⅰ△PL较对照组缩短,差异有统计学意义(P<0.05),耳鸣组Ⅴ△PL、Ⅰ~Ⅴ△IPL较对照组延长,差异有统计学意义(P<0.05)。 结论 DPOAE与高刺激率ABR可作为诊断耳鸣的一种客观检查方法,其对耳鸣的早期评估有重要的应用价值;增加ABR刺激速率,可提高耳鸣检测的敏感性。     

Distortion product otoacoustic emissions in patients with King-Kopetzky syndrome

In the present study, mild impairment of cochlear function in patients with King-Kopetzky syndrome was investigated using DPOAEs. A significant decrease in DPOAE levels in both ears was found in patients with King-Kopetzky syndrome compared with the controls after considering the thresholds as a co-variable. It is noteworthy that the global mean levels of DPOAEs were still significantly greater in controls than in patients with matched thresholds. Further frequency analyses showed a significant decrease in DPOAE levels over the mid- and high-frequency range in patients with better hearing thresholds when compared with those in the control group. Moreover, significantly smaller DPOAEs were found in the ears of patients with King-Kopetzky syndrome and without SOAEs, than in such ears of control subjects after considering the thresholds as a co-variable. However, when SOAEs were present there was no difference. Decreases in DPOAE level appear to represent evidence of minor cochlear pathology, and provide a pathological basis for the difficulty of hearing speech in the presence of background noise, which characterizes King-Kopetzky syndrome.

Sumario

En el presente estudio, se investigó una leve alteración en la función coclear en pacientes con el síndrome de King-Kopetzky usando DPOAE. Se encontró una disminución significativa en los niveles de intensidad de las DPOAE en ambos oídos en pacientes con este síndrome, al compararlos con los controles, luego de considerar el umbral como una co-variable. Es digno de resaltar que los niveles globales medios de las DPOAE fueron aún significativamente mayores en los controles que en los pacientes con umbrales correspondientes. Un análisis de frecuencia ulterior mostró una disminución significativa en los niveles de las DPOAE, en el rango de frecuencias medias y altas, en pacientes con los mejores umbrales auditivos, al compararlos con aquellos del grupo control. Más aún, se encontraron DPOAE significativamente menores en la audición de pacientes con el síndrome de King-Kopetzky y ausencia de SOAE, comparados con los oídos de sujetos control, luego de considerar el umbral como una co-variable. Sin embargo, cuando las SOAE estuvieron presentes, no hubo diferencia. La disminución en el nivel de intensidad de las DPOAE parece representar evidencia de patología coclear menor, y aporta una base patológica para explicar la dificultad para entender el lenguaje en presencia de ruido de fondo, que caracteriza al síndrome de King-Kopetzky.     

Behavioral thresholds for electrical stimulation applied to auditory brainstem nuclei in cat are altered by injurious and noninjurious sound

Each of three young-adult female cats with normal hearing received a total of eight permanent electrodes which were implanted bilaterally in cochlear nucleus (CN) and inferior colliculus (IC). Three experiments were performed using behaviorally measured thresholds for electrical stimulation of CN and IC. In Expt. 1, electrical stimulation thresholds (in dB re 1.0 μA) were obtained in the presence of a continuous tone of moderate intensity and in quiet. In comparison with quiet, electrical stimulation thresholds measured during tone were lower by as much as 15 dB (stimulation hypersensitivity). In Expt. 2, a brief exposure to an intense sound produced a temporary threshold shift (TTS) for acoustic stimuli but only produced small changes in electrical stimulation threshold. The acoustic stimuli used in Expts. 1 and 2 were termed noninjurious since no permanent hearing loss was produced. Expt. 3 employed an exposure to a white noise that resulted in a mean permanent threshold shift (PTS) of 34.1 dB for acoustic stimulation. The PTS was accompanied by a mean stimulation hypersensitivity of 9.6 dB. Comparing Expts. 1 and 3, it was shown that the transient hypersensitivity produced by the noninjurious continuous tone correlated strongly with the permanent hypersensitivity that was produced by the PTS. In regard to the origin of stimulation hypersensitivity, the suggestion is made that it is an indication of a physiological change localizable perhaps in the auditory nuclei of the upper brainstem.     

Estimation of the status of spiral ganglion neurons and Schwann cells in the auditory neural degeneration mouse using the auditory brainstem response

Conclusion: The auditory brainstem response (ABR) wave I threshold, latency and amplitude are insensitive to spiral ganglion neurons (SGNs) degeneration, but are sensitive to the degeneration of Schwann cells and can estimate the status of Schwann cells in a neural degeneration mouse model. The thorough pre-operative ABR assessment would be helpful in predicting cochlear implant performance.

Objectives: This study aimed in finding a non-invasive electrophysiological method to evaluate the status of the auditory nerve and the Schwann cells in sensorineural hearing loss (SNHL) and auditory neuropathy (AN) ears, and providing useful information for candidates screening and outcome prediction in cochlear implantation.

Methods: The frequency-specific acoustic ABR was recorded in mice. The immunohistochemical staining was performed to detect the SGNs and Schwann cells in mice cochlea. The correlations between ABR wave I metrics and SGNs, Schwann cells were investigated.

Results: In SNHL and AN mice cochlea, statistically significant correlations between ABR wave I thresholds, latencies and amplitudes at 8, 16, and 32?kHz and their corresponding SGNs densities were found only in wave I amplitude at 8?kHz. While the ABR wave I metrics at all three frequencies showed strong significant correlations with their corresponding Schwann cells densities.     

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。     

Speech-evoked auditory brainstem response with ipsilateral noise in adults with unilateral hearing loss

Introduction: Subjects with unilateral hearing loss (UHL) report difficulties in speech understanding in noise. Speech-evoked auditory brainstem response (S-ABR) provides cues for temporal and spectral encoding of speech in the brainstem. S-ABR recording in noise increases its sensitivity in evaluating the auditory processing and related disorders.

Objectives: Study speech encoding at the level of brainstem when the auditory system relies on one ear and to study the effect of noise on this encoding.

Subjects and method: This study included two groups: control group consisted of 15 adults with normal hearing sensitivity and study group consisted of 30 adults with UHL. The study group was further subdivided into two subgroups: study subgroup A (SG A) consisted of 15 adults with right functioning ears and study subgroup B (SG B) consisted of 15 adults with left functioning ears. S-ABR in quiet and with ipsilateral noise was recorded in both the groups using complex ABR advanced auditory research module.

Results: In UHL, there was a statistically significant delay in the S-ABR onset and offset in noise compared to quiet. Moreover, quiet–noise (+5 SNR) correlation was significantly low compared to NH. Furthermore, pitch representation (F0 amplitude) was significantly degraded with noise. In addition, there was a statistically significant noise-induced phase shift in the transition region of speech syllable in these subjects.

Conclusion: In monaural processing, pitch representation (F0 amplitude) and cross-phaseogram were the main affected domains. Speech phonemes of transient origin can be confused in subjects with UHL.     

Identifying hearing impairment and the associated impact on the quality of life among the elderly residing in retirement homes in Pretoria,South Africa

BackgroundAge-Related Hearing Loss (ARHL) is the most widespread sensory disorder in the elderly. Poor audiological support within retirement homes is one of the fundamental issues impacting the Quality of Life (QoL).ObjectivesThe objectives of this study were to: (1) Identify the presence of hearing impairment through a hearing screening test battery in a sample of elderly participants residing in three retirement homes. (2) Determine the psychological, communication-related and social impact of the hearing impairment on the QoL in a sample of elderly participants residing in retirement homes.MethodA prospective cross-sectional research design with quantitative methods of data analysis was used to obtain data from 70 elderly participants (mean age = 79 years, 79% were female). Ten of them used hearing aids. Hearing screening was conducted using otoscopy, tympanometry and air conduction screening (500 Hz–4 kHz). The World Health Organization Quality of Life (WHOQoL) questionnaire was adapted and utilised for the present study.ResultsFindings revealed that 77% of the sample obtained a refer result from the hearing screening protocol indicating a high presence of hearing impairment. Twenty-nine per cent (n = 16) of the participants felt depressed, worried and anxious because of their hearing loss and 20% of participants felt unaccepted by their significant others as a result of their hearing impairment. Hearing difficulties were significantly associated with a reduced QoL (p = 0.045). Eight of the 10 participants who wore hearing aids reported an overall improvement in QoL since receiving and utilising their hearing aids and 20% (n = 2) of hearing aid users reported challenges with maintaining their hearing aids.ConclusionThe findings of this study emphasised the need for an increased role for audiological services provided by audiologists within retirement homes, thereby contributing to an improved QoL.     

Metabolic Presbycusis: Differential Changes in Auditory Brainstem and Otoacoustic Emission Responses with Chronic Furosemide Application in the Gerbil

Auditory characteristics of metabolic or strial presbycusis were investigated using an animal model in which young adult Mongolian gerbils (Meriones unguiculates) were implanted with an osmotic pump supplying furosemide continuously to the round window. This model causes chronic lowering of the endocochlear potential (EP) and results in auditory responses very similar to those seen in quiet-aged gerbils (Schmiedt et al., J. Neurosci. 22:9643–9650, 2002). Auditory function was examined up to one week post-implant by measurement of auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs). Emission threshold was defined as the stimulus level required to reach a criterion emission amplitude. Comparing all responses on a threshold-shift diagram, where emission threshold increases were plotted versus ABR threshold increases, the following results were obtained: (1) On average, the increase of the emission threshold was about 55% of the increase in ABR threshold, with comparatively little scatter. (2) The main dysfunction in metabolic presbycusis appears to be a decrease in the gain of the cochlear amplifier, combined with an additional, smaller increase in neural threshold, both effects caused by a chronically low EP. (3) For ABR threshold increases over 20 dB, the points for the chronic low-EP condition were largely separate from those previously found for permanent acoustic damage. The threshold-shift diagram therefore provides a method for noninvasive differential diagnosis of two common hearing dysfunctions.