Evoked otoacoustic emissions in patients with acoustic neuromas

Click-evoked otoacoustic emissions were recorded in 28 patients with surgically proven acoustic neuromas and 22 patients with brain stem pathologic disorders. Data collected in acoustic tumor ears were compared with those obtained in 30 nontumor ears demonstrating sensorineural hearing losses. Acoustic emissions were altered (increased detection-threshold or no detectable emissions) in all ears with eighth nerve tumors and were not affected in those with brain stem pathologic conditions that do not involve cochlear function. The properties of acoustic emissions were similar in both tumor and nontumor ears with hearing loss, which suggests that acoustic tumors usually produce a cochlear hearing loss.     

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.     

Paradoxical effects of contralateral white noise on evoked otoacoustic emissions in ears with acoustic neuroma

A contralateral suppression effect on evoked otoacoustic emissions (EOAEs) is usually present in normally hearing subjects and in patients with sensorineural hearing loss, while it is absent or reduced in ears to which the vestibular nerve has been cut and in ears with acoustic neuroma (AN). To date, a paradoxical effect, that is an increase in EOAE amplitude during contralateral stimulation, has been described in one ear with sensorineural hearing loss of unknown aetiology and in three ears with AN (two in the present paper). Evidence has been provided that the contralateral suppression effect on EOAEs is accomplished largely, if not entirely, via the medial olivocochlear bundle (OCB). According to clinical data the absence or the reduced amount of contralateral suppression effect on EAOEs may be attributed to a totally, or partially, damaged or malfunctioning medial OCB. The way in which a contralateral noise may increase EOAE amplitude is more difficult to explain. One attractive hypothesis is that this paradoxical effect is a result of some pathological adaptive process in the medial OCB.     

Neonatal screening of deafness: evoked otoacoustic emissions or acoustic distortion products?]

Transiently evoked otoacoustic emissions (TEOAE) allows an auditory screening in neonates above 30 dB and between 2 kHz to 4 kHz. Another type of otoacoustic emissions, the distortion product (DP) allows a similar screening and provides more specific frequency information over a broader frequency range, including frequencies below 2 kHz and above 4 kHz. The goal of this study was to determine 1) the interest of distortion product in comparison with TEOAE in a auditory screening program in neonates; 2) The predictive value of information extracted from otoacoustic emissions recordings, on frequential parameters of distortion product (DP). In this prospective study, TEOAE and DP were successively recorded in 20 neonates (34 ears) with risk of hearing impairment, using the ILO92 software and hardware. When TEOAs were no detectable (9/34), the DPs were no detectable neither (10/34). When TEOAs were detectable, the Dps carried more specific frequency information above 1 kHz in 52 to 80% of the patients. DP amplitudes have been quantitatively correlated with TEOA energy bands. Correlations between DP and TEOA have been objectivized for DP2.5 and DP4 with OE2, and for DP4 and DP6 with OE5. The correlation predictive value was above 85%. In conclusion, this study demonstrated that analysis of TEOA spectrums procures frequential information without requiring DP recordings.     

新生儿自发性耳声发射与瞬态诱发性耳声发射的相关性

目的分析自发性耳声发射（spontaneous otoacoustic emission,SOAE）与瞬态诱发性耳声发射（transient evoked otoacoustic emission,TEOAE）之间的相关性。方法新生儿112例（224耳）,其中女59例,男53例,出生后2～4天内行SOAE及TEOAE检测。结果每耳SOAE信号峰数量与其TEOAE强度相关（r=0.43,P〈0.001）。每耳最大SOAE波幅与其TEOAE强度相关（r=0.49,P〈0.001）。不同耳依据其SOAE信号峰数量将其分为4组：I组无SOAE信号峰;II组为单SOAE信号峰;III组为2～3个SOAE信号峰;IV组为3个以上信号峰。I组TEOAE强度为（10.96±3.77）dBSPL,II组（12.87±3.27）dBSPL,III组（15.61±3.23）dBSPL,IV组（17.100±4.51）dBSPL,各组间的TEOAE强度差异均具有统计学意义。II组SOAE最大强度（-13.54±9.21）dBSPL,III组（-4.56±7.22）dBSPL,IV组（1.00±7.35）dBSPL,各组间最大SOAE波幅差异具有统计学意义。结论SOAE信号峰数量、最大SOAE波幅与TEOAE强度之间存在正相关关系,SOAE信号峰越多,最大SOAE波幅也越强,同时TEOAE强度也越强。     

听力正常耳鸣与诱发性耳声发射的关系

目的:分析听力正常的耳鸣患者的耳蜗功能,探讨耳鸣的客观检查手段。方法:对听力正常的单侧 耳鸣患者50例(50耳,耳鸣1组)、听力正常的双侧耳鸣患者23例(46耳,耳鸣2组)和正常人34例(68耳,对照 组)进行瞬态诱发耳声发射(TEOAE)和畸变产物耳声发射(DPOAE)。耳鸣1、2组同时进行耳鸣频率匹配检查, 并分析在TEOAE及DPOAE测试结果中有无相应表现。结果:①TEOAE通过率,耳鸣1组为64.0%,耳鸣2组 为91.3%,对照组为100%(1组P<0.01,2组P>0.05);②DPOAE通过率,3组均为100%;但耳鸣1组在 3.125kHz及8.837kHz的波幅均值较对照组低,两组差异具有统计学意义(P<0.05);③耳鸣音调分布为0.25 ～8.00kHz。在TEOAE频谱中及DPOAE听力图中,部分耳表现出与匹配频率相对应的低反应峰或频率成分 缺失以及低幅值。结论:部分听力正常的耳鸣患者已有耳蜗毛细胞的损害;TEOAE及DPOAE可以作为外周性 耳鸣诊断的一种客观检测方法;前者对耳蜗性耳鸣的早期诊断敏感而直观,而后者适用于耳鸣的频率分析。     

Age-related changes in evoked otoacoustic emissions

Outer hair cells of the organ of Corti play an important part in the genesis of evoked otoacoustic emissions (EOAEs), which are related to cochlear biomechanics. The aim of this study was to investigate the age factor in relation to EOAEs in 166 ears of subjects between 6 weeks and 83 years of age. The results show that when age increases, the presence of EOAEs by age group and the frequency peak in spectral analysis decrease, and EOAE threshold increases. Thus, there is an effect of age upon EOAEs, and it seems linked with alteration of cochlear biomechanics and/or hair cell loss. Such an effect has to be taken into consideration when EOAEs are used in clinical applications, and limits the use of EOAEs in older subjects.     

Intra- and intersubject variability of acoustically evoked otoacoustic emissions. I. Transiently evoked otoacoustic emissions]

BACKGROUND: Acoustically evoked otoacoustic emissions are becoming increasingly significant in the clinical monitoring of cochlear function in adults. Any interpretation of these measurements in a clinical setting must consider their intra- and intersubject variability. METHODS: Transiently evoked otoacoustic emission (TEOAE) measurements were performed in 32 normally hearing adults in three weekly test sessions. Each ear was tested twice per session, and the results were statistically analyzed. RESULTS: All test candidates had measurable TEOAEs. Statistically significant differences in TEOAE amplitudes were neither found between two measurements at the same day, nor at weekly intervals. No statistically significant amplitude differences were found between right and left ear of the same candidate. TEOAE amplitudes in women were always higher than in men with statistically significant differences in the 2, 3, and 4 kHz frequency band. CONCLUSIONS: These results indicate that monitoring of the inner ear status can be reliably performed using TEOAE measurements. Changes in TEOAE amplitudes effectively indicate changes in the cochlear function.     

Frequency and temporal analysis of contralateral acoustic stimulation on evoked otoacoustic emissions in humans

Previous studies have shown that the effect of contralateral acoustic stimulation (CAS) on ipsilateral evoked otoacoustic emissions (EOAE) depends somewhat upon the spectrum of the eliciting stimulus. The latency of the EOAE, however, is itself frequency-dependent. Consequently, two general ways of analyzing the effects of CAS may be considered: by frequency band or by temporal segment. In this study, we analyzed the effects of CAS both ways in the same subjects, essentially simultaneously. The frequency analysis of the EOAE derived from the wavelet transform (WT). The WT is known to provide a robust approach to the analysis of non-stationary signals and was anticipated to avoid possible time-frequency confounds of the cochlear mechanical system. For comparison, a more basic analysis - using a temporal moving window - was employed. The results largely support earlier findings and confirm that in humans the greatest suppression of EOAEs by CAS is obtained for lower frequency and/or longer latency EOAE components. Despite expectations for the WT analysis, the more basic, temporal, analysis tended to yield the clearer results.     

The sources of electrically evoked otoacoustic emissions

It has been hypothesized that electrically evoked otoacoustic emissions (EEOAEs) are generated at a site on the basilar membrane near the stimulating electrode. From this original site, the energy propagates towards the oval window, giving rise to the short time delay component (SDC) of EEOAEs. The energy also propagates towards its characteristic frequency (CF) location, and the emission reflected from the CF location forms a long time delay component (LDC). This hypothesis is directly tested in this study by using an acoustical swept tone to modulate the EEOAEs generated by alternating electric current delivered to the round window niche in gerbils. An acoustical tone with a high sound pressure level or a small frequency separation from the EEOAE frequency induced a strong suppression of the EEOAE LDC, but no obvious suppression of the SDC. When the electrical current frequency was fixed, the swept acoustic tone induced a slight suppression, an enhanced peak, and a strong suppression of EEOAEs as the acoustic frequency was swept from the low to high frequency. These data indicate that the electrical current induced cochlear partition vibration near the stimulating electrode. One part of this energy propagates directly to the ear canal, forming the SDC, and the other part propagates to its CF place and is reflected from there to the ear canal, forming the LDC.     

Clinical observations with evoked otoacoustic emissions at Mayo Clinic

Clinical applications of transient evoked otoacoustic emission (TEOAE) measures began in 1989 at Mayo Clinic Rochester. Normative data indicates: a) greater TEOAE level for women and right ears beginning in the teen years, b) mean TEOAE levels remain relatively stable through the first seven decades of life, c) between subject EOAE level variability for normal hearing adults is high (up to about 30 dB) while within subject variability is low (about 4 dB), suggesting EOAEs should not be used to estimate pure-tone thresholds but are valuable in monitoring hearing status. Good frequency specificity of TEOAEs is demonstrated across high frequency hearing loss. Examples of TEOAEs in differential diagnosis are provided for cases of sudden hearing loss, auditory neuropathy and eighth nerve tumors including pre and post operative testing assessing changes in auditory function related to surgical procedures. Finally, our experience with TEOAEs in newborn hearing screening is described.     

Transient evoked otoacoustic emissions in the elderly

The purpose of this study was to analyse the changes in transient evoked otoacoustic emissions (TEOAEs) with age. We studied 232 subjects above 60 years of age with a battery of audiological tests, including TEOAEs Our criterion for the presence of TEOAEs was based on a cut-off at overall wave reproducibility 55% or overall response level 4 dB SPL. The prevalence of TEOAEs in left ears was 55.6%. No TEOAEs were found in subjects with a pure-tone average (PTA) above 40 dB HL. In the subgroup with TEOAEs, a significant decrease in overall wave reproducibility with age was found. We compared 45 normal-hearing elderly subjects with TEOAEs with a control group of 20 normal-hearing young adults The elderly had significantly lower mean overall response levels and mean overall wave reproducibility. Average hearing level was significantly higher in the elderly than in controls We conclude that the prevalence of TEOAEs decreases with age, and that the overall response level and overall reproducibility decrease with age. This decrease may not be seen in isolation from the increase in hearing threshold level.     

Transient evoked otoacoustic emissions in rock musicians

Objective: Our focus in this study was the assessment of transient evoked otoacoustic emissions (TEOAEs) in a large group of rock musicians. A further objective was to analyse tinnitus among rock musicians as related to TEOAEs. Design: The study was a cross-sectional survey of rock musicians selected at random. A control group was included at random for comparison. Study sample: We recruited 111 musicians and a control group of 40 non-musicians. Testing was conducted by using clinical examination, pure tone audiometry, TEOAEs and a questionnaire. Results: TEOAE SNR in the half-octave frequency band centred on 4?kHz was significantly lower bilaterally in musicians than controls. This effect was strongly predicted by age and pure-tone hearing threshold levels in the 3–6?kHz range. Bilateral hearing thresholds were significantly higher at 6?kHz in musicians. Twenty percent of the musicians had permanent tinnitus. There was no association between the TEOAE parameters and permanent tinnitus. Conclusions: Our results suggest an incipient hearing loss at 6?kHz in rock musicians. Loss of TEOAE SNR in the 4?kHz half-octave frequency band was observed, but it was related to higher mean 3–6?kHz hearing thresholds and age. A large proportion of rock musicians have permanent tinnitus.     

Click evoked otoacoustic emissions in neonatal screening

Seven hundred and twenty-three neonates under intensive care have been tested by evoked otoacoustic emissions (EOAE) and the auditory brain stem response (ABR) to investigate the use of EOAE as a test for hearing impairment. Three hundred and thirty-one have had follow-up tests to the age of at least 2 years. The EOAE test has been found to be practical and quick to perform. The proportion of NICU infants producing a recordable EOAE is 80%, and the sensitivity and selectivity to the ABR result in the period up to 3 months post due date is 93 and 84%, respectively. These figures are high enough and the reduction in time compared to ABR is sufficient for the EOAE to be considered as the primary screen. The follow-up data show mixed results with both false positives and false negatives present. The incidence of severe hearing impairment is close to that expected from retrospective studies at 2 in 331 (1 bilateral, 1 unilateral). Firm conclusions on the sensitivity of EOAE to long-term hearing impairment await the results from larger numbers of infants and further follow up data.     

Transient evoked otoacoustic emissions in vestibular neuritis

OBJECTIVES: Partial or total degeneration of the vestibulocochlear anastomosis at its takeoff from the saccular ganglion and regenerating efferent neural buds under the cochlear outer hair cells (OHCs) have been found in the temporal bones of human patients with a history of vestibular neuritis (VN). We sought to test whether VN has any functional impact on the ipsilateral OHCs by means of transient evoked otoacoustic emission (TEOAE) testing. METHODS: We retrospectively analyzed prospectively collected TEOAE data of 28 patients (19 female, 9 male; age range, 21 to 60 years; median age, 42.5 years). The pure tone air conduction hearing thresholds at each standard audiometric frequency (0.125 to 8 kHz) and the amplitudes of the TEOAEs at the 1-, 2-, 3-, and 4-kHz frequency bands were compared between the lesional and contralateral sides by use of the nonparametric sign test for 2 paired samples. RESULTS: No significant difference was found in the pure tone air conduction hearing thresholds between the lesional and contralateral ears at any of the 11 standard tested frequencies. No significant difference was found between the TEOAE amplitudes of the lesional and contralateral sides. CONCLUSIONS: Subclinical OHC functional impairment is not present in VN. Moreover, no apparent significant changes in medial olivocochlear bundle resting activity accompany VN.     

听神经瘤的耳声发射观察

目的 观察和分析听神经瘤的耳声发射特点,为评估听神经瘤患者的耳蜗功能和选择保护听力的术式提供参考依据.方法 对20例（22耳）听神经瘤患者行纯音听阈、阻抗、听性脑干反应（auditory brainstem response,ABR）、诱发性耳声发射（evoked otoacoustic emissions,EOAE）测试及CT和（或）MRI扫描,能引出EOAE的瘤耳检测其自发性耳声发射（spontaneous otoacoustic emissions,SOAE）和传出抑制功能.结果 28.57%听神经瘤耳能引出EOAE,按其畸变产物耳声发射（distortion product otoacoustic emissions,DPOAE）特点分为三型：①“耳蜗型”3耳;②“非耳蜗型”2耳;③“混合型”1耳;“非耳蜗型”耳能引出强大的SOAE;能引出EOAE的6耳均有内侧橄榄耳蜗传出系统功能障碍.结论 EOAE可精确分析听神经瘤患者的耳蜗（外毛细胞）功能,部分听神经瘤病人存在“离断耳”现象.耳声发射（otoacousticemissions,OAE）在诊断重度感音神经性聋（包括听神经瘤病人）方面有一定潜能.     

Distorsion-products otoacoustic emissions in acoustic neuroma]

Eight cases with surgically confirmed 1.5-3.5 cm acoustic neuromas were tested through measuring distorsion-products otoacoustic emissions (DPO), which objectively reflects the cochlear status. Only one frequency (Ft) corresponding to behavior threshold highest dB HL is selected as a frequency site of DPO. The DPO is collected at a level of 75 dB SPL with equilevel of stimuli f1 and f2 and proper frequency separation (f2/f1 = 1.2). The frequencies of stimuli f1 and f2 can be calculated through the formula Ft=2f1-f2. Six cases with less than 3.0 cm neuromas had normal amplitude of DPO. Decreased amplitude of DPO is found in two cases suffered from 3.0-3.5 cm neuromas. The discrepancy between behavior threshold and amplitude of DPO can be an important indication for distinguishing early retrocochlear lesions, for instance, acoustic neuroma.     

Objective detection of transiently evoked otoacoustic emissions.

Newborn hearing screening with transiently evoked otoacoustic emissions (TEOAE) is a well-established method. A screening device must be equipped with a test procedure for objective TEOAE detection. The statistical tests implemented in the commercially available screening devices are the correlation, an estimation of the signal-to-noise ratio and a binominal test. The aim of the present study is to compare the TEOAE detection performance of these tests with that of several other tests in the time and frequency domains (variance ratio F(SP) and its modification F(SP)*, Friedman test, modified q-sample uniform scores test). The comparison was based on a data sample of 420 TEOAE. The frequency range examined was 1.5-4.0 kHz. As a new feature, two frequency sub-ranges (1.5-2.5 kHz, 2.5-4.0 kHz) were tested separately. The modified variance ratio F(SP)* was the most powerful test, whereas the tests implemented in the known screening devices showed the lowest detection performance.