耳蜗电图和ABR在听神经病诊断中的应用研究

目的:分析比较耳蜗电图和ABR测试在听神经病(AN)诊断中的作用。方法:AN组为AN患者16例(32耳),对照组为感音神经性听力损失患者20例(26耳)。对2组受试者行交替极性短声刺激耳蜗电图和ABR测试。分别观测AN组和对照组的波形,并进行以下对比:①比较AN组患者的ABR和耳蜗电图波形引出率;②比较AN组与对照组耳蜗电图的复合动作电位(CAP)潜伏期和绝对幅度,以及总和电位(SP)与CAP的幅度比值。结果:AN组32耳中有25耳引出-SP或CAP,耳蜗电图总体引出率为78.1%。AN组的CAP潜伏期短于对照组(P<0.05),CAP绝对幅度低于对照组(P<0.05),-SP/CAP幅度比值高于对照组(P<0.01)。AN组仅5耳引出不完整的ABR波形,引出率为15.6%,且波形分化较差。ABR引出率明显低于耳蜗电图(P<0.01)。对照组全部引出分化良好的耳蜗电图和ABR波形。结论:耳蜗电图和ABR在AN的诊断中各自发挥重要作用。AN患者听觉信息的时间整合作用受到损害而强度感受机制受影响较小。     

听力正常者交替短声诱发的耳蜗电图特征

目的 分析听力正常者交替短声诱发的耳蜗电图(ECochG)特征,为耳蜗电图的临床应用提供参照.方法 对听力正常者38人(49耳)行耳蜗电图检查.使用Nicolet Bravo诱发电位系统,用交替短声作为刺激信号.每只测试耳的起始测试强度为100 dB nHL,以10 dB为步距逐渐降低强度,直至无法引出CAP.观测各强度下CAP的潜伏期和幅度、CAP阈值以及高强度(90 dB nHL)下SP/CAP幅度比值.绘制CAP的输入-输出曲线.结果 49耳均引出良好ECochG波形,平均引出反应阈为28.37±6.81 dB nHL.CAP峰潜伏期随刺激强度降低而延长.高强度下-SP与CAP幅度比为0.27±0.14.CAP幅度的I/0曲线呈明显的低、高两个强度段,在60 dBnHL附近存在明显的拐点.结论 听力正常者耳蜗电图可作为临床诊断的参照依据.CAP的I/0曲线及-SP/CAP幅度比可提供耳蜗病变的诊断信息.CAP的潜伏期和阈值可反应耳蜗内、外毛细胞的功能.     

突发性聋患者耳蜗电图分析

目的分析突发性聋(简称突聋)患者耳蜗电图无波形引出者听力损失程度及有波形引出者中-SP、AP振幅,探讨该病患者耳蜗电图特点及该病与内淋巴积水的关系。方法记录电极放置在紧贴鼓膜紧张部中央的位置,记录62例突聋患者患耳(66耳)和健耳(51耳)的耳蜗电图,分别测量两组中-SP、AP的振幅,并记录无波引出者的听力损失程度。结果两组-SP振幅分别为:患耳0.30±0.38μV,健耳0.16±0.13μV,差异有统计学意义(P<0.05);AP振幅分别为:患耳0.82±0.85μV,健耳0.69±0.49μV,差异无统计学意义(P>0.05)。-SP/AP比值分别为:患耳0.38±0.15,健耳0.27±0.12,两组比较差异有统计学意义(P<0.01)。31.82%患耳-SP/AP比值异常增高,9.80%健耳-SP/AP异常增高。突聋患者患耳无波形引出者纯音听阈89.0±17.8dBHL,与有波形者纯音听阈(58.1±18.4dBHL)比较,差异有显著统计学意义(P<0.01)。结论突聋患者患耳较多出现-SP/AP比值异常增高,提示突聋可能与内淋巴积水有关。     

听神经病患者最大言语识别率与主客观听力学特征的相关性分析

目的总结并分析听神经病患者最大言语识别率与其他客观测听结果之间的相关性,探讨最大言语识别率在诊断听神经病中的意义。方法 106例(212耳)听神经病患者均进行最大言语识别率、畸变产物耳声发射、听性脑干反应测试、耳蜗电图、40Hz事件相关电位、听性稳态反应测试,分析主客观听力测试与最大言语识别率测试的关系。应用PASW Statistics 18.0统计软件处理数据。结果听神经病患者最大言语识别率较好组与较差组中轻度到重度听力损失均有出现,PBmax程度在总体水平上与听力损失程度和听力曲线类型相关;PBmax程度与镫骨肌反射之间具有统计学意义,引出或部分引出声反射耳总体水平好于未引出声反射耳;ABR检查212耳中,仅有12耳能引出重复性不佳的ABR波,引出波形比例为5.7%(12/212),阈值均≥80d Bn HL,ABR可记录到波形组的PBmax程度显著好于ABR无反应组(P<0.05);-SP/AP比值在PBmax不同组别之间,其PBmax具有显著性差异(P<0.05),-SP/AP<0.5组及比值介于0.5-1.0组的患耳PBmax程度最好,-SP/AP比值>1时程度较差。PBmax与40Hz事件相关电位、听性稳态反应阈值呈负相关(P<0.05)。结论听神经病患者最大言语识别率与主客观听力学特征密切相关,PBmax的测试水平是听觉通路上不同病变部位功能障碍或缺失的综合反映,间接体现了AN患者从周边到中枢一系列非同步化反应的变化。PBmax联合主客观听力测试对分析听神经病病变部位,判断病变程度具有重要的临床参考价值。     

听神经病的病变部位探讨

目的探讨听神经病的发病部位.方法总结12例听神经病患者的病史、纯音及言语听力、镫骨肌反射、听性脑干反应(auditory brainstem response,ABR)、耳蜗电图、耳声发射及对侧声抑制试验的特点.结果12例的耳蜗电图-SP均消失.结论听神经病的发病部位在耳蜗的内毛细胞.     

豚鼠耳蜗电图及听觉脑干电位同步记录法的探讨

采用单通道分别记录和双通道同步记录法,检查30只正常豚鼠的耳蜗电图(ECochG)和听觉脑干电位(ABR),比较两者的波形、潜伏期、振幅及阈值。结果提示同步记录法对ECochG和ABR的波形,潜伏期、振幅及阈值均无明显影响;ECochG N_1与ABR I波潜伏期差异无显著性意义。认为:采用同步记录N_1～V或I～V间期,可提高耳蜗及蜗后病变的鉴别诊断价值。     

听神经病患者耳蜗电图-SP、AP幅度分析

目的分析听神经病患者耳蜗电图中-SP、AP的幅度,探讨该病患者-SP/AP比值增高的原因.方法用银球电极放置在鼓膜后下方,记录听神经病患者和正常人的耳蜗电图,分别测量两组中-SP、AP的幅度.结果听神经病患者-SP幅度与正常组无明显差异(P＞0.05),而AP幅度两组存在极显著差异(P＜0.001).结论听神经病患者-SP/AP比值增高的原因是由于AP幅度的明显降低而造成.     

听神经病患者的耳蜗电图特征

目的:了解听神经病患者的耳蜗电图特征。方法:用外耳道银球电极记录听神经病组和正常对照组的耳蜗电图,比较两者的-SP波幅差异,统计患耳AP出现的情况。结果:听神经病患者-SP波的引出率为100％,并且其波幅与正常对照组的差异有显著性意义(P<0.01)。AP波幅较小,但引出率高达84％。结论:听神经病患者的-SP可引出且波幅增大。     

急性低频感音神经性聋临床发病特征和诊断

目的 探讨急性低频感音神经性聋(acute low-frequency sensori neural hearing loss,ALHL)的临床发病特征和诊断方法 ,以期避免误诊,提高诊断率.方法 回顾性分析34例(35耳)ALHL的临床表现、听力学检测结果 和4～5年的随访情况,总结ALHL的临床发病特征.结果 本组34例(35耳)ALHL呈急性发病,年龄21～47岁.男11例(32%),女23例(68%).单侧占97.06%(33/34例),双侧占2.94%(1/34例).28例(29耳)伴低调耳鸣、耳部堵闷或胀满感.0.125～1 kHz平均听阈为29.92±10.61 dB HL,2～8 kHz平均听阈为9±3.94 dBHL.听性脑干反应(ABR)各波潜伏期及波间期正常.耳蜗电图(ECochG)-SP幅值异常增大占54.28%,-SP/AP比值异常增大占65.71%.畸变产物耳声发射(DPOAE)在低频区引出率为24.28%,高频区引出率约为97.71%.随访4～5年,31例(91.18%)于初次发病后至今未再复发.结论 ALHL以单侧发病为主,常伴低调耳鸣、耳部堵闷及胀满感.该病多见于青年女性.PTT以低频听阈升高为特征.ABR正常,ECochG示-SP幅值及-SP/AP比值增大.     

单侧听神经病儿童的听力学特征分析北大核心CSCD

目的 分析儿童单侧听神经病(Unilateral Auditory Neuropathy,UAN)听力学特点,为该类儿童诊断提供可靠依据。方法 回顾分析12例UAN儿童(男8人,女4人),平均年龄3.92岁(1-7岁)。对比38例(76耳)双侧(Auditory Neuropathy,AN)病例,分析游戏测听(Play audiometry,PA)、听性脑干反应(Auditory brainstem response,ABR)、稳态听觉诱发电位(Steady-state auditory evoked potential,ASSR)、耳蜗微音器电位(Cochlear microphonic potential,CM)以及耳声发射(Otoacoustic emission,OAE)的临床听力学特点。结果 (1)UAN组儿童PA阈值比双侧AN组儿童更高,极重度听力损失占33.33%,完全听力损失占66.67%;(2)UAN组儿童PA阈值显著高于双侧AN组,UAN组儿童ASSR阈值与双侧AN组无显著性差异;(3)UAN组儿童ABR阈值引出率为50%,高于双侧AN组的25%。结论(1)UAN更具隐匿性,较之双侧AN,其临床特征并不显著,UAN行为测听表现出的听力损失更加严重,多表现为极重度、完全听力损失;(2)在儿童听力学诊断当中遵循交叉验证原则极其重要,单侧ABR严重异常或纯音测听/PA显示单侧听力损失的儿童都应进行AN的核心评估组合,如CM、OAE与ABR测试。     

The correlation between ECochG parameters and early auditory behavior after cochlear implantation in children

Objective: The individual outcome after cochlear implantation in children with auditory synaptopathy/neuropathy (AS/AN) is difficult to predict. A tool for preoperative assessment would be helpful for counseling parents. This study evaluates the outcome after CI in children with AS/AN and with sensorineural hearing loss (SNHL), and correlates it with the preoperative ECochG results in order to find specific parameters of prognostic value. Design: The improvement of auditory behavior after CI was retrospectively assessed using the LittlEARS questionnaire and quantified in a score (LS). This score was correlated with the CAP/SP ratio in the preoperative ECochG. The score was further correlated with the patient’s age six months following CI. Study sample: Nine children with AS/AN were compared to nine children with SNHL. Results: Both groups showed a significant improvement in LS following CI. There was a significant positive correlation between the CAP/SP ratio and the improvement in LS in all children. The correlation between age and LS was significantly negative in the SNHL group and positive in the AS/AN group. Conclusion: All children with AS/AN and SNHL benefit to a similar extent from CI. The preoperatively assessed CAP/SP ratio has a prognostic value for the development of auditory behavior following CI.     

Simultaneous recording of electrocochleogram and auditory brainstem responses

A method which can record and plot the electrocochleogram (ECochG) and auditory brainstem response (ABR) simultaneously with the same tracing was studied. The results demonstrated that the ECochG waves obtained by our method and that recorded alone were very similar. The -SP/AP values and the latencies of ABR obtained by those two methods had no statistically significant difference. It could help the recognition of ABR waves, particularly wave I. This technique was more beneficial in determination of wave I-V interpeak latencies and in differential diagnosis between cochlear and retro-cochlear lesions.     

Frequency-specific electrocochleography indicates that presynaptic and postsynaptic mechanisms of auditory neuropathy exist

OBJECTIVES: The physiological mechanisms underlying auditory neuropathy (AN) remain unclear and it is likely that the multiple disruptions are classified under the broadly defined term. Cochlear implantation is being more widely used in this population to bypass the suspected site-of-lesion although a number of cases have been identified within the Sydney Cochlear Implant Centre where this management strategy has been unsuccessful. It is likely that this relates to the different physiological mechanisms underlying AN. DESIGN: To investigate the site-of-lesion in AN, frequency-specific round window electrocochleography (ECochG) was used to assess local hair-cell, dendritic, and axonal currents generated within the cochlea in 14 subjects with AN and compared with responses from two normally hearing subjects. ECochG results were then compared with electrically evoked auditory brain stem response (EABR) measured after cochlear implantation. RESULTS: The results of this study demonstrate that two dominant patterns of ECochG waveforms (produced by a high-frequency alternating tone burst) can be identified in this population of AN subjects: (a) gross waveform showing a prolonged summating potential (SP) latency that, in most cases, is followed by a small compound action potential; and (b) gross waveform showing a normal latency SP waveform followed by a broad negative potential [assumed to reflect the dendritic potential (DP) identified in anaesthetized guinea-pigs]. This study demonstrates that in most subjects (n = 7) with a prolonged latency SP but no DP, normal morphology EABR waveforms were elicited for all electrode channels. On the other hand, all subjects (n = 7) who showed a normal latency SP followed by a broad negative DP, showed EABR waveforms that were absent or having poor wave V morphology. The authors' interpretation of this is that ECochG results may provide a classification of AN into pre- and postsynaptic lesions. CONCLUSIONS: We suggest that a presynaptic and postsynaptic type of AN exist that may have implications for the fitting of cochlear implants.     

Audiological and electrocochleography findings in hearing-impaired children with connexin 26 mutations and otoacoustic emissions

We recorded cochlear potentials by transtympanic electrocochleography (ECochG) in three hearing-impaired children with GJB2 mutation who showed otoacoustic emissions. Pure tone thresholds, distortion product otoacoustic emissions (DPOAEs) and, auditory brainstem responses (ABRs) were also obtained. Subjects 1 (35delG/35delG) and 3 (M34T/wt) had profound hearing loss and showed the picture of auditory neuropathy (AN) as DPOAEs were detected with absent ABRs in both ears. The hearing impairment found in subject 2 (35delG/35delG) was profound in the right ear and moderate in the left ear. Both DPOAEs and ABRs with normal latencies and morphology were recorded only from the left ear. On the ECochG recording the cochlear microphonic was obtained from all children. No compound action potential (CAP) was detected in subject 1. A neural response was recorded only from the left ear in subject 2 with a threshold corresponding to the audiometric threshold while no CAP was detected on the right side. The ECochG obtained from subject 3 showed a low-amplitude broad negative deflection which was identifiable down to low stimulus levels. This response decreased in amplitude and duration when utilizing a high-rate stimulation paradigm. The amount of amplitude reduction was close to that calculated for normal ears, thus revealing the presence of an adapting neural component. These findings indicate that patients with GJB2 mutations and preserved outer hair cells function could present with the picture of AN. The hearing impairment is underlain by a selective inner hair cell loss or a lesion involving the synapses and/or the auditory nerve terminals. We suggest that neonatal hyperbilirubinemia may play a role in protecting outer hair cells against the damage induced by GJB2 mutations.     

The SP-AP compound wave in patients with auditory neuropathy

CONCLUSIONS: This study suggests that the asynchronization of the cochlear afferent pathway may be one mechanism of the etiopathogenesis of auditory neuropathy. OBJECTIVE: To investigate the characteristics of the SP-AP compound wave and its generating mechanism in patients with auditory neuropathy. SUBJECTS AND METHODS: The electrocochleogram (ECochG) was recorded with external ear canal electrode in patients with auditory neuropathy and normal subjects. The peak-latency, amplitude, and time course of the SP-AP compound wave were measured by using an 'assessor-blind' study. The discrepancy between the two groups was evaluated by statistical analysis. RESULTS: The SP-AP compound waveform in the auditory neuropathy patient group was unrepresentative. The transient character of the SP-AP compound wave was more atypical than that for the normal cases. SP dominance (-SP/AP>0.4) appeared. The amplitude of both AP and SP was lower than that of the control group. The width of the SP-AP compound wave at one-third of its peak was greater than that of the control group.     

Electrocochleography in auditory neuropathy

Auditory neuropathy (AN) is a disorder characterized by the absence or the severe impairment of the auditory brainstem responses (ABRs) together with the preservation of otoacoustic emissions and/or cochlear microphonic (CM). We recorded transtympanic electrocochleography (ECohG) evoked by 0.1 ms clicks in one young adult and in four children having distortion product otoacoustic emissions and absent ABRs. In all but one patient CM and summating potential (SP) were present with normal threshold, and their amplitudes appeared comparable to or higher than the values obtained from subjects with normal hearing. The compound action potential (CAP) was absent in two patients while in one subject CM and SP were followed by a highly desynchronized neural activity. A broad CAP was found in two children and the threshold appeared clearly elevated in one of them, while it showed only a mild elevation in the other. No correlation was found between CAP and behavioral thresholds. These results suggest that ECohG can be useful in AN diagnoses since it is the only reliable tool in evaluating the auditory peripheral function in the presence of a desynchronized ABR.     

Auditory neuropathy/auditory dys-synchrony detected by universal newborn hearing screening

The implementation of neonatal hearing screening has enabled early detection and intervention in hearing loss. The use of otoacoustic emissions (OAE) and auditory brainstem response testing in universal screening has led to the recognition of this recently described disorder called auditory neuropathy/auditory dys-synchrony (AN/AD). This diagnosis indicates that the infant has significant hearing loss despite having normal outer hair cells in the cochlea. We reviewed the characteristics and natural history of nine infants detected to have AN/AD from universal newborn hearing screening in a national pediatric hospital. Fifty-two cases of hearing loss were detected from 14,807 consecutively screened cases. Of the 52 cases, 9 had electrophysiological test results consistent with AN/AD. They include both premature infants who had major neonatal complications and term infants with no perinatal complications. Six cases had bilateral and three cases had unilateral findings. We suggest that AN/AD can occur in low-risk infants and hence screening of high-risk cases alone is insufficient. Our findings are discussed with reference to the current literature.