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.     

Effects of contralateral white noise on click-evoked emissions in normal and sensorineural ears: towards an exploration of the medial olivocochlear system.

The association between contralateral stimulation and evoked otoacoustic emissions (EOAEs) allows study of sound-evoked olivocochlear feedback and then of the medial olivocochlear system. A method allowing quantification of sound-evoked olivocochlear feedback is proposed. The feedback is present in almost all normal-hearing subjects, but with great interindividual variability. In sensorineural hearing loss, the feedback is present in 20 out of 21 subjects. One paradoxical clinical case is described with a unilateral increase of EOAE intensity during contralateral stimulation.     

畸变产物耳声发射对侧抑制效应的临床应用价值

目的：为观察畸变产物耳声发射（ＤＰＯＡＥ）对侧抑制效应的临床应用价值。方法：研究以白噪声为对侧声刺激,对１７例正常人（３４耳）,１３例蜗性聋（１３耳）,９例蜗后聋（９耳）进行了ＤＰＯＡＥ及其对偶抑制效应测试。结果：蜗性聋耳的ＤＰＯＡＥ幅值较正常耳显著下降（Ｐ〈０．０１）,对偶抑制效应减弱,但与正常人差异无统计学意义（Ｐ〉０．０５）,蜗后聋耳ＤＰＯＡＥ幅值高于正常耳（Ｐ〉０．０５）,对侧抑制效应显著     

Activation of medial olivocochlear efferent system in humans: influence of stimulus bandwidth

The activity of the medial olivocochlear bundle (MOCB) can be studied in humans through variations in the level of evoked otoacoustic emissions (EOAEs) elicited by contralateral acoustic stimuli (CAS). The present study sought to investigate how the activity of the MOC system at a given frequency, as measured through the contralateral suppression of tone-pip EOAEs, depends on the bandwidth of the contralateral stimulus. EOAEs were recorded in 155 normal-hearing subjects, successively with and without contralateral stimuli whose bandwidth, center frequency and level were systematically varied. We showed a clear dependence of contralateral EOAE suppression on bandwidth demonstrating increased suppression with increased bandwidth over about two octaves around the center frequency of the noise. This effect was obtained irrespective of whether contralateral noise energy was kept constant independently of bandwidth or not, which indicates a role of bandwidth per se in contralateral EOAE suppression. Results are interpreted in terms of a simple model of MOCB activation mechanisms including peripheral bandpass filtering, within-channel compression and across-channel spatial summation by the afferent paths. Complementary experiments suggested a greater effectiveness of increases in bandwidth on the upper than on the lower side and of frequency components akin to or remote from the test frequency than of intermediate bands. Finally, these results were complemented by detailed spectrum analyses of the EOAE level variations induced by the different noises, which revealed that whilst noise components close to or remote from the center frequency generally attenuated EOAE level, intermediate components could in some cases lead to a relative increase in EOAE level. These results can further be explained by assuming different positive and negative weights on the inputs to the spatial summation process depending on their position relative to the center frequency.     

Evoked otoacoustic emissions: correlates between spectrum analysis and audiogram

Correlations between spectrum analysis of evoked otoacoustic emissions (EOAEs) and hearing losses have been calculated in 150 patients with pure sensorineural hearing loss. Significant correlations were found. The greater the high-frequency spectral components of the EOAE, the better the high-frequency hearing. However the relationship is complex, and it does not seem possible to establish an audiogram knowing only the spectrum analysis of EOAEs.     

听神经瘤致聋机理——14例(16耳)听神经瘤病人听力测试结果分析

目的 :探讨听神经瘤听力损失的病理生理机制。方法 :对 14例 (16耳 )听神经瘤患者行纯音听阈、阻抗、听性脑干反应 (ABR)、诱发耳声发射测试 (EOAE)及 CT和 (或 ) MRI扫描。 EOAE能引出的 4耳还检测其传出抑制功能 ,ABR不能检测且 EOAE不能引出的重度聋 (听力损失大于 80 d B)有 5耳行鼓岬刺激试验 (PST)。结果 :16耳听神经瘤中2耳 (12 .5 0 % )听力损失源于神经性损害 ;6耳 (37.5 0 % )蜗性损害 ;8耳 (5 0 % )蜗 -神经性损害。能引出 EOAE的 4耳均有传出功能障碍。结论 :EOAE可评价听神经瘤的耳蜗功能状态 ;ABR结合 PST能分析听神经瘤的蜗后神经功能。听神经瘤的听觉病理可同时或单独发生于听外周的耳蜗水平、第 对颅神经 (传入神经 )水平和橄榄核耳蜗传出神经水平。     

Contralateral suppression of transient evoked otoacoustic emissions in patients with cerebello-pontine angle tumor.

OBJECTIVE: During measurement of transient evoked otoacoustic emissions (TEOAEs), acoustic stimulation of the contralateral ear reduces or suppresses TEOAE amplitude. This is thought to be due to the inhibitory control that the medial efferent auditory nerve exerts on outer hair cell (OHC) function. The main aim of this study was to investigate the effect of cerebello-pontine angle (CPA) tumor on the medial efferent nerve pathways to both tumor and non-tumor ears by examining alterations in TEOAE amplitude that result from contralateral acoustic stimulation. DESIGN: Contralateral suppression of TEOAEs using broadband noise was measured preoperatively in 17 patients with unilateral CPA tumor and 17 normally hearing controls, matched for age and gender. RESULTS: The control ears demonstrated significantly more suppression than the tumor and non-tumor ears in the patient group. There was, however, no significant difference in suppression between the tumor and non-tumor ears, and the statistical correlation for suppression between them was high. There was no effect of gender, hearing threshold levels, or size and type of tumor on suppression, although there was an effect of age on suppression in both the control and patient groups where suppression reduced as age increased. Four of the 17 patients had TEOAEs, which were clearly present in the tumor ear despite substantial hearing loss, three of which had no measurable hearing. CONCLUSIONS: It is hypothesized that neural compression by CPA tumor disrupts the medial efferent nerve control mechanism to the OHCs of tumor ears. It also is hypothesized that neural compression reduces transmission of afferent nerve impulses from the tumor ear, which cross over to the medial olivo-cochlear complex and reduce the inhibitory control of OHC function in the non-tumor cochlea.     

Evoked otoacoustic emissions and their modification by contralateral acoustic stimulation]

The active vibration of the basilar membrane as well as evoked otoacoustic emissions (EOAE) are probably based on the motile properties of cochlear outer hair cells (OHC). In the present study we examined the effects of contralateral acoustic stimulation on ipsilateral EOAE and thereby the active cochlear micromechanics. Contralateral white noise with intensities below 30 dB HL enhanced the EOAE amplitude, whereas higher sound levels reduced the evoked acoustic emissions. Similar effects of contralateral acoustic stimuli on ipsilateral EOAE were observed in patients with a conductive hearing loss. However, the required sound levels were higher compared to probands with normal hearing. In controls with unilateral deaf patients white noise up to 60 dB HL did not alter the EOAE amplitude. We concluded, that in patients with normal hearing or unilateral conductive hearing loss, effects of contralateral acoustic stimulation on evoked ipsilateral sound emissions may be due to the activation of crossed olivo-cochlear efferents reaching the OHCs.     

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.     

Evoked otoacoustic emissions: a fundamental and clinical survey

Evoked otoacoustic emissions (EOAEs) hold some promise as a fast, objective and noninvasive procedure to study the cochlea at the outer hair cell level. This paper summarizes the fundamental aspects of EOAEs, in particular their relationship with the active biomechanical properties of the cochlea. The properties of EOAEs are analyzed in normally hearing ears, in ears with sensorineural hearing loss, especially in Ménière's disease, in acoustic neuromas and in central deafness; the properties of EOAEs were also evaluated as to their suitability for screening auditory dysfunction in infants.     

Differential effects of ear-canal pressure and contralateral acoustic stimulation on evoked otoacoustic emissions in humans.

The effect of ear canal pressure variation (ECPV) on click evoked otoacoustic emissions (EOAEs) was compared to the suppressive effect observed with contralateral acoustic stimulation (CAS) in 11 healthy subjects. Both total EOAE amplitude and amplitude of 200 Hz frequency bands (22) were analyzed. Our results revealed that the ECPV as the CAS induced a decrease of the total EOAE amplitude; these two factors showed an additive effect when they are conjoint. The study of the EOAE frequency bands showed that the majority of them decreased under CAS and ECPV; however, a few bands are not affected. Moreover, it appeared that amplitude of the EOAE frequency bands were not modified in a similar way between the two factors: indeed some bands around 4.1 kHz did not decrease either by CAS or ECPV. These results suggest that these applied factors exert different actions on EOAEs. Moreover, the lack of a decrease effect for the same bands, both with CAS and ECPV, may explain the vulnerability of some cochlear locations.     

听神经病的临床与听功能特征

目的:探讨听神经病的临床与听功能特征。方法:总结分析54例听神经病患者的临床资料、听力学测试及电生理检查情况。结果:纯音听力图呈上升型70耳,覆盆型25耳,平坦型5耳,下降型4耳;低频、中频及高频平均阈值为(67.63±15.30,43.61±16.28,32.25±14.80)dB HL。声导抗鼓室图全部正常,77耳镫骨肌声反射消失,31耳声反射阈部分增高。听性脑干反应(ABR)全部未引出。畸变产物耳声发射(DPOAE)正常引出,26例行对侧声抑制未受影响。16例言语识别率差,与纯音听阈不成比例。23例颞骨CT或MRI未见异常。10例伴有周围神经病。结论:ABR自波Ⅰ起缺失而DPOAE正常引出,言语分辨力差与纯音听阈不成比例,镫骨肌声反射及OAE交叉抑制异常,纯音听力图多呈上升型以低频损失为主,是听神经病听功能的重要特征。提示病损主要位于耳蜗内听神经纤维。应与一般的感音神经性聋和中枢性聋相鉴别。     

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.     

Growth of evoked otoacoustic emissions during the first days postpartum. A preliminary report.

Evoked otoacoustic emissions (EOAEs) were recorded twice in 20 ears of 15 newborns. The recordings were performed in a room of the well baby ward, using the ILO88 in its default setting, i.e. with click stimulation. On the first test occasion, the infants were between 3 and 51 h of age, and EOAEs were identified in 10 ears. On the second test occasion, while the infants were at least 1 day older (range 42-107 h), EOAEs were present in all ears. The second EOAE was stronger, so the EOAE appeared to grow in the first days postpartum. This might be due to middle ear clearance of amniotic fluid, shortly after birth. The results of the EOAEs of the second examination were compared with 10 EOAEs in adult ears. The response levels of the newborns were significantly higher than in the adults. The (cross)-correlation peak value of the two tests' waveforms is over 0.75, however sometimes only after filtering around the most pronounced emission frequencies. The study proves that newborns failing the EOAE screen in the first 24 h after birth can pass if retested 1 day later, simply because of growth of EOAE strength.     

婴幼儿单侧听神经瘤

目的：探讨婴幼儿单侧听神经病（AN）神经生理学特点。方法：对3例单侧AN患儿在采集病史和耳科检查的基础上,行系统的听力学检查,包括声阻抗、镫骨肌反射、听性脑干反应（ABR）、耳蜗微音电位（CM）、诱发耳声发射（EOAE）、中潜伏期反应（MLR）和事件相关电位（ERP）以及CT和（或）MRI及周围神经系统检查。结果：3例患儿鼓室图均呈“A”型,健耳的同侧和交叉镫骨肌反射可正常引出,而患耳的同侧和交叉镫骨肌反射未引出。3例患儿双侧EOAE有效引出,健耳的ABR正常引出,思耳的ABR未引出,但CM均正常。3例患儿双耳均记录到MLR及ERP。影像学和周围神经系统未见异常。结论：单侧AN与双侧AN有相似的神经生理学特点。对婴幼儿单侧AN的诊断应着重分析其神经生理学特点,建议联合应用EOAE、ABR、CM和影像学检查。应对AN患儿定期随访。     

Ear surgery in osteogenesis imperfecta. Clinical findings and short-term and long-term results

Preoperative and postoperative hearing results and long-term results of stapedectomy have been investigated in 58 ears (47 patients) with osteogenesis imperfecta. After 3 months, hearing gain had been achieved in 49 (85%) of 58 ears. Twenty-seven (68%) of 40 ears followed up for an average of 9.6 years (range, 2 to 24 years) had no deterioration of their immediate postoperative hearing gain. In the other ears, the decrease in hearing gain in the long term was due to progression of the sensorineural component of the hearing loss. Complete closure of the air-bone gap remained unchanged in 26 (70%) of 37 ears. In 5 (9%) of 58 ears the sensorineural component of the hearing loss increased as an immediate result of the operation. In 6 other ears (10%) progressive sensorineural hearing loss was seen only after more than 1 year. A natural course of the disease is assumed as the cause because progressive sensorineural hearing loss has also been seen in the nonoperated on contralateral ears of these patients.     

Screening for auditory dysfunction in infants by evoked oto-acoustic emissions

Auditory threshold using auditory brain-stem responses (ABR) was determined in 30 ears from normally-hearing infants and 16 ears from infants with sensorineural deafness. In the same population, evoked oto-acoustic emissions (EOAEs) in response to a click of 20-dB hearing level were recorded. The presence of EOAEs was correlated with ABR thresholds. Evoked oto-acoustic emissions were always present when ABR wave V threshold was equal to or below 30-dB hearing level. On the contrary, infants with ABR thresholds higher than 40-dB hearing level never had EOAEs. As the recordings of EOAEs could be obtained more rapidly than ABR thresholds (average duration: five minutes vs 40 minutes), EOAEs could hold some promise as an objective, easy, and noninvasive test for screening auditory dysfunction in infants.     

Distortion-product otoacoustic emissions in humans with high frequency sensorineural hearing loss

Distortion-product otoacoustic emissions (DPOAEs) and pure-tone behavioral thresholds were compared in 20 ears with normal hearing and in 20 ears with high-frequency sensorineural hearing loss. The purpose was to determine if DPOAE amplitude is associated with pure-tone behavioral threshold. Comparison of results from the two groups of ears indicated that DPOAEs were reduced in amplitude or were absent in ears with high-frequency hearing loss. The differences occurred at frequencies above 1,500 Hz. Comparing results from 750 to 8,000 Hz within the same ear revealed a frequency-related correspondence of elevated behavioral threshold to reduced DPOAE amplitude. When behavioral thresholds were better than 20 dB HL, DPOAE amplitude was within the range (+/- 2 SDs) determined for the ears with normal hearing. When pure-tone threshold was greater than 50 dB HL, DPOAEs were absent or were significantly attenuated in 16/17 subjects (94%). The association of emission level with behavioral threshold level was variable when threshold was between these two extremes. Results imply that the measurement of DPOAEs has clinical potential as a means of detecting hearing loss by frequency.     

Growth of Evoked Otoacoustic Emissions during the First Days Postpartum: A Preliminary Report

Evoked otoacoustic emissions (EOAEs) were recorded twice in 20 ears of 15 newborns. The recordings were performed in a room of the well baby ward, using the ILO88 in its default setting, i.e. with click stimulation. On the first test occasion, the infants were between 3 and 51 h of age, and EOAEs were identified in 10 ears. On the second test occasion, while the infants were at least 1 day older (range 42–107 h), EOAEs were present in all ears. The second EOAE was stronger, so the EOAE appeared to grow in the first days postpartum. This might be due to middle ear clearance of amniotic fluid, shortly after birth. The results of the EOAEs of the second examination were compared with 10 EOAEs in adult ears. The response levels of the newborns were significantly higher than in the adults. The (cross-)correlation peak value of the two tests' waveforms is over 0.75, however sometimes only after filtering around the most pronounced emission frequencies. The study proves that newborns failing the EOAE screen in the first 24 h after birth can pass if retested 1 day later, simply because of growth of EOAE strength.