Diagnostik des kochleären Verstärkers mit DPOAE-Wachstumsfunktionen

Extrapolated DPOAE growth functions can be applied in ENT diagnostics for a specific assessment of cochlear dysfunction. In screening newborn hearing, they are able to detect transitory sound conductive hearing loss and thus help to reduce the rate of false positive TEOAE responses in the early postnatal period. Since DPOAE growth functions are correlated with loudness functions, DPOAEs offer the potential for basic hearing aid adjustment, especially in children. Extrapolated DPOAE I/O-functions provide a tool for a fast, automated frequency-specific and quantitative evaluation of hearing loss. However, DPOAE diagnostics is limited to a hearing loss of 50 dB HL. Thus, a combined measurement of DPOAE and AMFR would be useful.     

High-frequency hearing impairment assessed with cochlear microphonics

Abstract Conclusion: Cochlear microphonic (CM) measurements may potentially become a supplementary approach to otoacoustic emission (OAE) measurements for assessing low-frequency cochlear functions in the clinic. Objective: The objective of this study was to investigate the measurement of CMs in subjects with high-frequency hearing loss. Currently, CMs can be measured using electrocochleography (ECochG or ECoG) techniques. Both CMs and OAEs are cochlear responses, while auditory brainstem responses (ABRs) are not. However, there are inherent limitations associated with OAE measurements such as acoustic noise, which can conceal low-frequency OAEs measured in the clinic. However, CM measurements may not have these limitations. Methods: CMs were measured in human subjects using an ear canal electrode. The CMs were compared between the high-frequency hearing loss group and the normal-hearing control group. Distortion product OAEs (DPOAEs) and audiogram were also measured. Results: The DPOAE and audiogram measurements indicate that the subjects were correctly selected for the two groups. Low-frequency CM waveforms (CMWs) can be measured using ear canal electrodes in high-frequency hearing loss subjects. The difference in amplitudes of CMWs between the high-frequency hearing loss group and the normal-hearing group is insignificant at low frequencies but significant at high frequencies.     

正常听力男女的畸变产物耳声发射的比较

为了解听力正常人畸变产物耳声发射(Distortion product otoacoustic emissions,DPOAE)性别上的差异,采用Celesta-503耳声发射分析仪对18～24岁正常听力男女各12名进行DPOAE“听力图”和输入/输出曲线测试.结果显示两性的DPOAE检出率均为100%,其图形完全相似;但女性幅值高于男性,阈强度低于男性,且在一定频率范围内这种差别有统计学意义;女性斜率小于男性,但差异无统计学意义.文中还对其机理进行了初步探讨.     

Sensitivity of distortion product otoacoustic emissions in noise-exposed chinchillas

The present study investigates the effect of small amounts of outer hair cell (OHC) loss on distortion product otoacoustic emission (DPOAE) levels and evoked potential permanent threshold shifts (PTS) in a population of 12 noise-exposed chinchillas. The group mean DPOAE level, which decreased by up to approximately 15 dB in the presence of less than 8 dB PTS and 15% OHC loss, indicates that DPOAEs can detect an underlying cochlear pathology (i,e., OHC damage/loss) despite the presence of normal to near normal thresholds. The sensitivity of DPOAEs in detecting OHC loss makes this test measure suited for diagnosing sensorineural hearing impairment, particularly when abnormal auditory symptoms (i.e., speech discrimination problems) are associated with a normal audiogram in the clinical setting and as part of a hearing conservation program.     

Correlation between DPOAE I/O functions and pure-tone thresholds

Different studies have been carried out in order to correlate audiometric thresholds and distortion product otoacoustic emissions measurements (DPOAE). However, high variability and external interferences make hearing thresholds estimates by means of the DPOAE very little sensitive. The aim of this study was to check the correspondence between the pure tone thresholds and the cochlear response thresholds by DPOAE Input/output functions, considering the influence of the following variables: gender, past of acute otitis media, and ear side.MethodProspective study comprehending 69 normal hearing individuals. Multiple mix regression models were applied to evaluate the correspondence between the two measurements studied.ResultsStatistically significant positive correlation was observed among all the frequencies compared (2000, 3000, 4000 e 6000 Hz).ConclusionsThe 1dB HL resolution pure tone thresholds and the above-mentioned variables had a direct impact on the high correlation between the measures studied, and it also reduced response variability. Nevertheless, response variability was still high, limiting the use of DPOAE I/O functions for hearing threshold estimates. We suggest that these variables should be considered for future studies with pure tone thresholds estimations by DPOAE I/O functions.     

Multiple auditory steady-state responses in children and adults with normal hearing, sensorineural hearing loss, or auditory neuropathy

OBJECTIVES: We tested the clinical effectiveness of multiple auditory steady-state responses (ASSRs) for the objective assessment of hearing thresholds in patients with and without hearing loss, candidates for cochlear implants, and children with auditory neuropathy. METHODS: The study sample included 29 subjects with sensorineural hearing loss (SNHL), 18 candidates for cochlear implants, 11 subjects with auditory neuropathy, and 18 subjects with normal hearing thresholds. Behavioral hearing thresholds and ASSRs to carrier frequencies of 0.5, 1, 2, and 4 kHz were obtained. Special care was taken to minimize possible aliasing and high-intensity multiple stimulation effects. Differences and correlations between the ASSRs and the behavioral thresholds were determined. RESULTS: The ASSR estimation of behavioral thresholds in the normal-hearing group was elevated, whereas very close predictions were found for the SNHL group. The correlations between the two measures ranged from 0.86 at 0.5 kHz carrier frequency to 0.94 at 2 kHz. In the cochlear implant candidates and the auditory neuropathy group, the ASSR thresholds generally overestimated the behavioral audiogram. In these groups the number of detected ASSRs was higher than the number of behavioral responses, especially for the high-frequency carrier stimuli. CONCLUSIONS: Multiple ASSRs may reliably predict the behavioral threshold in subjects with SNHL and may serve as a valuable objective measure for assessing the hearing threshold across different frequencies in candidates for cochlear implants and children with auditory neuropathy.     

Clinical relevance of distortion product emissions by means of receiver operating characteristic (ROC) analysis.

The clinical use of distortion product otoacoustic emissions (DPOAE) stems from the observation that the outer hair cells are the most vulnerable part of the cochlea, and damage to these cells is associated with hearing loss and loss of DPOAE. The purpose of this study is to evaluate the applicability of DPOAE in predicting hearing thresholds under clinical conditions. DPOAE measurements (L1 = L2 = 70 dB SPL. f2/f1 = 1.20) of 219 hearing-impaired and normal hearing ears were analyzed. Recordings were acquired for DPOAE at 2 f1-f2 varying from 635 to 4052 Hz. The detectability of DPOAE in hearing-impaired subjects exhibited a strong hearing threshold dependence. Receiver operating characteristic (ROC) analysis yielded the highest sensitivity and specificity for threshold levels of about 30 dB at low frequencies and for threshold levels of about 60 dB at high frequencies. In addition, the separability of groups with different hearing status was more reliable at high frequencies as compared to low frequencies. The DPOAE provide an objective assessment of cochlear function. However, prognosis of hearing thresholds on the basis of DPOAE measurements depends strongly on the test frequency and is associated with large errors. Hence, the clinical use of DPOAE in predicting hearing thresholds is limited.     

对侧刺激声影响畸变产物耳声发射临床意义的探讨

观察白噪声对畸变产物耳声发射输入输出函数曲线影响，探讨其临床价值。方法：检测临床患者６１例，包括单纯性耳鸣不伴有听力下降患者３２例；以低频听力下降为主的耳聋患者２７例；蜗后病变２例。     

畸变产物耳声发射与响度重振现象关系的探讨

目的 探讨响度重振与耳蜗主动机制异常之间的关系，为耳声发射用于诊断耳蜗性病变提供更多指标。方法 通过对２０例（４０耳）健康人、５０例（６３耳）常规重振检测频率阳性者和１１例（１５耳）蜗后性聋耳进行畸变产物耳声发射（ｄｉｓｔｏｒｔｏｎ ｐｒｏｄｕｃｔ ｏｔｏａｃｏｕｓｔｉｃ ｅｍｉｓｓｉｏｎ，ＤＰＯＡＥ）的输入－输出（Ｉ／Ｏ）曲线的测试和分析。结果 重振检测阳性患耳不同频率ＤＰＯＡＥ的Ｉ／Ｏ曲线斜率     

畸变产物耳声发射与响度重振现象关系的探讨

目的探讨响度重振与耳蜗主动机制异常之间的关系，为耳声发射用于诊断耳蜗性病变提供更多指标。方法通过对２０例（４０耳）健康人、５０例（６３耳）常规重振检测频率阳性者和１１例（１５耳）蜗后性聋耳进行畸变产物耳声发射（ｄｉｓｔｏｒｔｉｏｎｐｒｏｄｕｃｔｏｔｏａｃｏｕｓｔｉｃｅｍｉｓｉｏｎ，ＤＰＯＡＥ）的输入－输出（Ｉ／Ｏ）曲线的测试和分析。结果重振检测阳性的患耳不同频率ＤＰＯＡＥ的Ｉ／Ｏ曲线斜率的均值与健康人对应频率Ｉ／Ｏ曲线斜率的均值相比明显增大（Ｐ＜０．０１），其ＤＰＯＡＥ的检测阈也明显提高。结论响度重振与耳蜗主动机制异常有特定联系，ＤＰＯＡＥ的Ｉ／Ｏ曲线对耳蜗主动机制的评价更直观、准确，可能成为一种有价值的诊断耳蜗性病变的指标。     

Middle ear and cochlear disorders result in different DPOAE growth behaviour: implications for the differentiation of sound conductive and cochlear hearing loss

Input/output functions of distortion product otoacoustic emissions (DPOAE I/O-functions) give an insight into the compressive, non-linear sound processing of the cochlea. With an inner ear dysfunction a steeper I/O-function is observed. Due to the linear sound processing of the middle ear, one can assume that the DPOAE growth behaviour remains unaltered with a sound conduction dysfunction. If that is true, a differentiation between middle and inner ear dysfunction will be possible by using the slope of DPOAE I/O-functions as a means for assessing cochlear compression. In order to test that hypothesis, DPOAE I/O-functions were recorded in a wide primary tone level range at up to 8 f2 frequencies between 2.0 and 8.0 kHz (15 dB SPL < L2< 60 dB SPL; L1=0.46 L2 + 41 dB SPL; f2/f1=1.2) in guinea pigs in which middle (saline solution in the bulla) and inner ear (exposure to loud broadband noise) disorders were induced. Middle ear dysfunction resulted in a reduction of the DPOAE amplitude independent of the primary tone level. Consequently, DPOAE growth behaviour was not affected. In contrast to that, during cochlear impairment, steepened DPOAE I/O-functions were observed reflecting loss of compression of the cochlear amplifier. Accordingly, DPOAE I/O-functions allow a differentiation between middle and inner ear dysfunction. Further studies will have to show the usability of this method for clinical diagnostics, e.g. for detecting sound conduction disturbances in newborn hearing screening due to amniotic fluid or Eustachian tube dysfunctions during the early postnatal period.     

Superficial siderosis of the central nervous system. A case report on examination by ECoG and DPOAE

This is a case of superficial siderosis of the central nervous system (SSCN). The diagnosis of SSCN was based on the result of T2-weighted magnetic resonance imaging and on suggestive clinical manifestations. The pure-tone audiogram showed bilateral progressive sensorineural hearing loss with a poor speech discrimination score and Jerger type IV. The remarkable elevation of the detective threshold of cochlear microphonics on electrocochleography was found and distortion product otoacoustic emission (DPOAE) showed no response: These electrophysiologic examinations, including electrocochleography and DPOAE, revealed that the progressive sensorineural hearing loss in this case was caused by both retrocochlear and cochlear damages.     

Evolution of recruitment at different frequencies during the development of endolymphatic hydrops in the guinea pig

The study of human temporal bones has identified endolymphatic hydrops as a common feature of several diseases. In particular it is systematically found in those bones removed from patients with premortem Menière's disease. Menière's disease is known to induce sensorineural pathology with recruitment, which changes with the evolution of the hearing loss, and is suspected to induce a cochlear conductive loss by a possible increase in static pressure of endolymph. Amplitude/intensity functions of sensorineural responses can reflect recruitment and/or conduction loss. Experimentally induced hydrops in animals provokes cochlear physiological alterations, some of which closely resemble certain features of Menière's disease. In the present study using a guinea-pig animal model, we have examined amplitude/intensity functions at the round window for cochlear microphonics (RWCM), summating potentials (RWSP) and action potentials (CAP) at different stages of hearing loss in experimentally induced hydrops. During the period of fluctuating thresholds there was reduction of maximal RWCM amplitude, no change in RWSP and recruitment on the CAP. At a later stage when the audiogram was flat and fluctuations were no longer seen, RWCM remained unchanged. At this time RWSP could show recruitment while CAP amplitudes at all intensities were reduced, indicating either a cochlear conductive loss and/or a general depression of neural activity.     

The clinical utility of distortion-product otoacoustic emissions

Otoacoustic emissions permit, for the first time, an unbiased means of examining the preneural elements of the peripheral auditory pathway that make the initial contribution to the perception of acoustic stimuli. Distortion-product otoacoustic emissions (DPOAEs) represent one type of evoked emission that has significant potential for becoming an important test in the audiometric evaluation of hearing capacity. In the present review, selected examples of several forms of sensorineural hearing loss demonstrate that DPOAEs have the ability to act as objective indicators of the frequency/level configuration of the conventional audiogram in cases in which hearing impairment results primarily from damage to the outer hair cells. In contrast, normal DPOAE functioning, in the presence of a significant hearing loss, indicates a locus of damage central to the region of the outer hair cells. Like the other emitted responses, DPOAEs can be measured noninvasively, are highly repeatable, under test-retest conditions, and are simple and rapid to detect using microcomputer-based instrumentation. Further, DPOAEs test both the "threshold" and suprathreshold levels of outer hair-cell activity in the form of response/growth functions, over a 30- to 40-dB stimulus range. In combination, these attributes indicate that DPOAEs can provide an objective and comprehensive assessment of the cochlear reserve of a given ear.     

畸变产物耳声发射在舰艇艇员听力调查中的应用

目的了解舰艇艇员的听力状况并探讨纯音听力图与DPOAE听力图的关系。方法对100名(200耳)舰艇艇员进行纯音、声导抗、DPOAE测试,测试仪器均为GSI系列产品。根据纯音测听结果将其分成正常、低频听力下降、高频听力下降及全频听力下降四个组,并结合纯音听力图与DPOAE听力图进行比较。结果纯音听阈正常组的DPOAE检出率及DPOAE振幅明显高于低频听力下降组、高频听力下降组及全频听力下降组(P＜0.01或0.05);DPOAE听力图与纯音听力图个各在频率均有很好的对应关系。结论DPOAE作为一种评价耳蜗毛细胞功能状态,在征兵、部队听力普查中较传统的纯音听阈测试更有意义。     

Analysis of the distortion product otoacoustic emission (DPOAE) and input/output function (I/O) in tinnitus patient with normal hearing

Distortion Product Otoacoustic Emission (DPOAE) has been used as a tool to determine the presence of cochlear pathology. It is well known that the damage of Outer Hair Cells (OHCs) results in reduced auditory sensitivity and generation of tinnitus. At the same time tinnitus arises in normal hearing persons as well. The aim of this study was the assessment of the DPOEA amplitude and the behavior of DP I/O function in tinnitus patients with normal hearing threshold. The group of 48 tinnitus patients (92 ears) with normal hearing threshold and the control group of 30 normal hearing patients (40 ears) were investigated for this study. All subjects have undergone the measurement of DPOAE and DP I/O functions for frequencies: 1000, 2000 and 4000 Hz. In the tinnitus group there were observed the decrease in DPOAE amplitude for some frequencies and the steeper slope of I/O function. This means that the places with localized damage or dysfunction of OHCs on the basilar membrane can be responsible for the origin of tinnitus.     

Impaired cochlear function correlates with the presence of tinnitus and its estimated spectral profile

The presence of tinnitus often coincides with hearing loss. It has been argued that reduced peripheral input leads to frequency-specific increase in neuronal gains resulting in tinnitus-related hyper-activity. Following this gain-adaptation hypothesis, impaired cochlear function should be predictive of the presence and spectral characteristics of tinnitus. To assess cochlear function, perceptual thresholds and distortion product otoacoustic emissions (DPOAEs) were measured with high frequency resolution for subjects with tinnitus and non-tinnitus control subjects (N?=?29 and N?=?18) with and without hearing loss. Subjects with tinnitus also provided a 'tinnitus likeness spectrum' by rating the similarity of their tinnitus to tones at various frequencies. On average, subjects with tinnitus had elevated thresholds, reduced DPOAE, and increased slope of the DPOAE input-output function in the range from 4 to 10?kHz. These measures were strongly correlated and were equally predictive of the presence of tinnitus. Subjects with a pronounced edge to their hearing loss profile were very likely to have tinnitus. In the group average, the tinnitus likeness spectrum was correlated with perceptual thresholds (r?=?0.98, p?相似文献   

Evolution of recruitment at different frequencies during the development of endolymphatic hydrops in the guinea pig

Summary The study of human temporal bones has identified endolymphatic hydrops as a common feature of several diseases. In particular it is systematically found in those bones removed from patients with premortem Menière's disease. Menière's disease is known to induce sensorineural pathology with recruitment, which changes with the evolution of the hearing loss, and is suspected to induce a cochlear conductive loss by a possible increase in static pressure of endolymph. Amplitude/intensity functions of sensorineural responses can reflect recruitment and/ or conduction loss. Experimentally induced hydrops in animals provokes cochlear physiological alterations, some of which closely resemble certain features of Menière's disease. In the present study using a guinea-pig animal model, we have examined amplitude/intensity functions at the round window for cochlear microphonics (RWCM), summating potentials (RWSP) and action potentials (CAP) at different stages of hearing loss in experimentally induced hydrops. During the period of fluctuating thresholds there was reduction of maximal RWCM amplitude, no change in RWSP and recruitment on the CAP. At a later stage when the audiogram was flat and fluctuations were no longer seen, RWCM remained unchanged. At this time RWSP could show recruitment while CAP amplitudes at all intensities were reduced, indicating either a cochlear conductive loss and/or a general depression of neural activity.     

Influence of Ketamine–Xylazine Anaesthesia on Cubic and Quadratic High-Frequency Distortion-Product Otoacoustic Emissions

Ketamine is a dissociative anaesthetic, analgesic drug as well as an N-methyl-d-aspartate receptor antagonist and has been reported to influence otoacoustic emission amplitudes. In the present study, we assess the effect of ketamine–xylazine on high-frequency distortion-product otoacoustic emissions (DPOAE) in the bat species Carollia perspicillata, which serves as model for sensitive high-frequency hearing. Cubic DPOAE provide information about the nonlinear gain of the cochlear amplifier, whereas quadratic DPOAE are used to assess the symmetry of cochlear amplification and potential efferent influence on the operating state of the cochlear amplifier. During anaesthesia, maximum cubic DPOAE levels can increase by up to 35 dB within a medium stimulus level range from 35 to 60 dB SPL. Close to the -10 dB SPL threshold, at stimulus levels below about 20-30 dB SPL, anaesthesia reduces cubic DPOAE amplitudes and raises cubic DPOAE thresholds. This makes DPOAE growth functions steeper. Additionally, ketamine increases the optimum stimulus frequency ratio which is indicative of a reduction of cochlear tuning sharpness. The effect of ketamine on cubic DPOAE thresholds becomes stronger at higher stimulus frequencies and is highly significant for f2 frequencies above 40 kHz. Quadratic DPOAE levels are increased by up to 25 dB by ketamine at medium stimulus levels. In contrast to cubic DPOAEs, quadratic DPOAE threshold changes are variable and there is no significant loss of sensitivity during anaesthesia. We discuss that ketamine effects could be caused by modulation of middle ear function or a release from ipsilateral efferent modulation that mainly affects the gain of cochlear amplification.     

Effects of cigarette smoking on distortion product otoacoustic emissions

This study measured distortion product otoacoustic emissions (DPOAEs) and DPOAE input/output (I/O) curves to assess the effects of smoking on cochlear function. Twenty-four healthy adults, 12 smokers and 12 nonsmokers in the 20-30 years age range were selected based on self-reported histories of five to eight years of smoking or no smoking, respectively. All subjects received tympanometric screening to rule out middle ear pathology. Conventional (0.25-8 kHz) and ultra high frequency (UHF; 10-20 kHz) audiometry showed normal or age-appropriate thresholds across both groups. DPOAE results showed small, but significant, decline in DPOAE levels without concomitant changes in noise floors in smokers as compared to nonsmokers. I/O detection thresholds were also significantly elevated at high frequencies in smokers as compared to their nonsmoking counterparts. These findings indicate that smokers are at greater risk for cochlear damage than nonsmokers, and that DPOAE amplitudes and I/O detection thresholds may identify early changes in cochlear function in smokers.