DPOAE对系统性低血压患者的耳蜗功能监测及其临床意义

目的用畸变产物耳声发射(distortion-product otoacoustic emission,DPOAE)来观察系统性低血压和慢性进行性听力损伤的关系。方法实验组为34例体检中发现的系统性低血压患者(诊断标准:舒张压<60mmHg,收缩压<90mmHg),对照组由年龄、性别相匹配的30例正常人组成,两组在同一实验室中进行了生化、心血管、耳鼻咽喉专科和纯音测听、声阻抗、DPOAE等听力学检查。将两组的各项结果进行比较。结果实验组DPOAE听力图结果显示16例患者有一个以上频率轻到中度的听力损伤,主要在低频范围。与对照组相比,实验组的DPOAE幅值在一个以上的频率低下甚至缺失。结论系统性低血压有可能是导致耳蜗功能损伤的因子之一,而DPOAE可作为早期监测此类患者耳蜗功能损伤情况的有效工具。     

The effects of anesthesia on otoacoustic emissions

We have measured transient-evoked and distortion-product otoacoustic emissions (OAEs) in the chinchilla and compared them in the awake and anesthetized animal (using either ketamine or barbiturate agents). We report a significant increase in OAE amplitudes during anesthesia, particularly using ketamine. These effects are most evident for transient-evoked otoacoustic emissions (TEOAEs) as measured in the non-linear mode. Our data support the hypothesis that tonic activity levels in cochlear efferents may be reduced by anesthetic effects, either directly or indirectly (e.g., by general reductions in descending pathway activity), and that reduced cochlear efferent activity will result in the observed increase of OAE amplitudes.     

Adaptive Wiener Filtering for Improved Acquisition of Distortion Product Otoacoustic Emissions

An innovative acoustic noise canceling method using adaptive Wiener filtering (AWF) was developed for improved acquisition of distortion product otoacoustic emissions (DPOAEs). The system used one microphone placed in the test ear for the primary signal. Noise reference signals were obtained from three different sources: (a) pre-stimulus response from the test ear microphone, (b) post-stimulus response from a microphone placed near the head of the subject and (c) post-stimulus response obtained from a microphone placed in the subjects nontest ear. In order to improve spectral estimation, block averaging of a different number of single sweep responses was used. DPOAE data were obtained from 11 ears of healthy newborns in a well-baby nursery of a hospital under typical noise conditions. Simultaneously obtained recordings from all three microphones were digitized, stored and processed off-line to evaluate the effects of AWF with respect to DPOAE detection and signal-to-noise ratio (SNR) improvement. Results show that compared to standard DPOAE processing, AWF improved signal detection and improved SNR. © 1998 Biomedical Engineering Society. PAC98: 4364Jb, 4360-c, 8790+y     

遗传性无综合征耳聋一家系畸变产物耳声发射测试

目的　探索遗传性进行性无综合征耳聋患者的听功能改变特点。方法　一个常染色体显性遗传进行性无综合征耳聋家系 5 2名成员及听力正常组 15名 ,进行了纯音测试及畸变产物耳声发射 (distortionproductotoacousticemissions,DPOAE)测试。结果　无综合征耳聋家系中 34名成员纯音测试为感音神经性聋 ,其中纯音听阈均值 (puretoneaverage ,PTA)≥ 40dB的 15例 (2 9耳 )DPOAE反应缺失 ,PTA≤ 35dB伴高频下降的 12例 (2 3耳 )DPOAE高频或高、中频振幅下降或缺失 ;2 1名 (42耳 )纯音听阈正常成员中 ,有 12例 (15耳 )DPOAE高频或高、中频振幅下降或缺失。结论　DPOAE能鉴别出耳蜗亚临床的病理改变 ,对该病的早期诊断 ,遗传咨询有指导意义。     

畸变产物耳声发射对侧抑制效应的研究

利用ＩＬＯ９２耳动态分析仪，测试２３例（４６耳）正常青年人的畸变产物耳声发射（ＤＰＯＡＥ）和对侧窄带噪声（ＮＢＮ）的影响。结果：（１）对侧ＮＢＮ对ＤＰＯＡＥ的抑制非常明显，随ＮＢＮ强度增加ＤＰＯＡＥ幅值下降增加，二者呈显著负相关（Ｆ２为１～６ｋＨｚ，γ为－０．４９～－０．２４，均Ｐ〈０．０５，斜率０．２６～０．０８ｄＢ／１０ｄＢ）。（２）在Ｆ２为中频（１．２ｋＨｚ）且为中等强度（４５～６５ｄＢＳＰ     

听力正常人畸变产物耳声发射的基本特性

利用动态分析仪ＩＬＰＯ－９２，对４８例听力正常人在４组不同原始刺激强度下进行畸变产物耳声发射检查，结果发现平均ＤＰＯＡＥｓ图呈双叶型轮廓：在１．５ｋＨｚ和５ｋＨｚ附近。     

Acoustical modulation of electrically evoked otoacoustic emission in intact gerbil cochlea

In order to study the interaction between mechanical-electrical and electrical-mechanical transductions of outer hair cells (OHCs) in vivo, we observed the acoustically induced changes in the electrically evoked otoacoustic emission (EEOAE). One pole of a bipolar electrode was placed in the round window niche and the other pole on the surface of the first cochlear turn in the gerbil. A microphone and a speaker were used to monitor the EEOAE and to deliver an acoustical tone, respectively. It was found that a high sound level acoustical tone enhanced the EEOAE fine structure at frequencies below the acoustical frequency, and suppressed the overall level of the EEOAE at frequencies above the acoustical frequency. In addition, the EEOAE at frequencies approximately one half octave lower than the acoustical frequencies were relatively more enhanced or showed relatively less suppression than at other frequencies. The amplitudes of these changes had a positive relationship with acoustical tone levels. Furosemide eliminated the acoustically caused EEOAE change indicating that the acoustically caused change in the EEOAE is a phenomenon of the normal cochlea. One possible mechanism for the results is that the electrically and acoustically evoked basilar membrane (BM) vibrations interact at the EEOAE generation site and change the local mechanical and electrical properties. The second possible mechanism is that the acoustical stimulus creates an impedance discontinuity at its characteristic frequency location leading to a change in the reflected electrically evoked traveling wave, which may enhance or suppress the EEOAE by the vector summation of two waves.     

The Effects on Transient Evoked Otoacoustic Emissions Following Changes in External Auditory Canal Acoustic Impedance

The form of the transient evoked otoacoustic emission (TEOAE) generated by an acoustic impulse and recorded in the external auditory canal is dependent on many factors. Of these, the acoustic impedance of the external canal is possibly the most important. The effect of a change of acoustic impedance on the TEOAEs, induced by filling the external canal with helium or sulphur hexafluoride gas, is measured in a group of normal hearing subjects. The fundamental frequency of the TEOAEs is found to depend upon the density of the gas in the external canal. Compared to that of air (density 1.29 g/1) the frequency increased with helium (density 0.178 g/1) and decreased with sulphur hexafluoride (density 6.6 g/1). The amplitude of the TEOAEs was also found to depend upon the density of the gas in the canal, decreasing with helium and increasing with sulphur hexafluoride. These results suggest that the TEOAEs observed in the group of subjects tested arose within the external auditory canal. This does not imply that cochlear emissions are not generated in response to transient acoustic impulses, rather it implies that this study failed to show the presence of a cochlear-mediated emission.     

The effects of spinal anesthesia on auditory function in pediatric patients

ObjectivesPersistent or transient hearing loss (HL) is a less-recognized complication of spinal anesthesia (SA) in the pediatric population, although it has been previously reported in adults. The primary aim of this study was to investigate the effects of SA on auditory function in the pediatric population.MethodsAfter gaining institutional approval and parental consent, 30 American Society of Anesthesiologists physical status I-II children between 4 and 15 years undergoing lower extremity orthopedic surgery were enrolled in this prospective study. Spinal blocks were performed in the midline with a 25G Quincke needle using 0.5% hyperbaric bupivacaine. Transient evoked otoacoustic emission (TEOAE) and distortion product otoacoustic emission (DPOAE) tests were administered before surgery and one-day postoperative. Children with detected HL were retested on postoperative day seven. Preoperative and postoperative results were compared. A Wilcoxin Signed-Ranks test (with Bonferroni correction) was used for statistical analyses.ResultsThere was no statistically significant HL in the postoperative period compared to the preoperative period. In 29 of 30 patients, no difference was detected at any frequency tested. In one patient, TEOAE and DPOAE tests were found to be decreased on postoperative day one. In this patient, control tests were found to be improved on postoperative day seven.ConclusionsAdministration of SA may results in a low probability of transient hearing loss with no clinical significance in children 4–15 years of age.