短期铅暴露对成年豚鼠听性脑干反应的影响

摘要：目的观察短期铅暴露对成年豚鼠听性脑干反应（auditory brainstem response, ABR）的影响。方法将24只听力正常的成年黑目花色豚鼠随机分为4组（A、B、C、D组,每组6只）,分别用含醋酸铅浓度为2 mmol/L的铅水进行喂养0、15、30及60 d,所有动物均在实验结束时测试双耳ABR并断头采血检测血铅浓度。结果各组动物的血铅浓度分别为A组（58.91±7.76）μg/L、B组（659.00±62.71）μg/L、C组（733.00±68.96）μg/L、D组（701.80±54.75）μg/L。各组动物由click诱发的ABR阈值分别为A组（25.91±3.75）dB SPL、B组（23.57±5.56）dB SPL、C组（26.88±5.94）dB SPL、D组（25.63±5.00）dB SPL,各组动物之间比较,差异无统计学意义（P>0.05）。在70 dB SPL 的click声刺激下,随着铅暴露时间的延长,I波潜伏期出现延长的趋势,但差异无统计学意义（P>0.05）;30 d及60 d与对照组相比,III波振幅出现减小,其差异具有统计学意义（P<0.01）。结论短期铅暴露（2个月内）对成年豚鼠ABR阈值无明显影响,但铅暴露时间超过30 d,从耳蜗传导到中脑的听觉信号强度开始出现下降。     

不同龄豚鼠听性脑干反应和耳蜗核形态比较

为比较出生后不同时间及成年豚鼠听性脑干反应、耳蜗核结构、各亚核团细胞形态、细胞面积和密度，测试了出生后１２、２４、４８小时和成年豚鼠各５、５、９、２８只的听性脑干反应，部分作脑干切片，光学显微镜观察耳蜗核及各亚核团细胞形态，计算机图像处理系统测试前腹侧核和后腹侧核细胞面积和密度，发现（１）新生豚鼠除ＡＢＲ反应阈较成年豚鼠高平均１０ｄＢ外，波形、各波潜伏期和波间期无显著差异。（２）跟猫、沙土鼠和蝙蝠一样，新生豚鼠和成年豚鼠耳蜗核也可分为三个亚核团：背侧核（ＤＣＮ）、前腹侧核（ＡＶＣＮ）和后腹侧核（ＰＶＣＮ）。（３）豚鼠耳蜗核各亚核团内细胞分型也跟猫相似，ＡＶＣＮ内有大球细胞、小球细胞和球形细胞；ＰＶＣＮ内有章鱼细胞、多极细胞和球形细胞；ＤＣＮ内有颗粒细胞、锥形细胞和巨细胞。（４）成年豚鼠各亚核团平均细胞密度较新生豚鼠明显降低，出生１２小时到成年鼠ＡＶＣＮ和ＰＶＣＮ细胞密度分别减少２５．１３％和２２．１７％。（５）新生豚鼠ＡＶＣＮ细胞平均面积是成年组的８３．３６％，ＰＶＣＮ是成年组的９３．０４％。比较本实验测量的细胞密度和面积的改变和猫出生后到成熟耳蜗核细胞的资料，分析差异较大的可能原因。     

正常豚鼠听性脑干反应与听性稳态反应的对比

目的 比较正常豚鼠听性脑干反应(ABR)和听性稳态反应(ASSR)阈值的差异,为利用豚鼠进行听力学研究提供理论依据.方法 选正常听力豚鼠12只(24耳),在戊巴比妥钠镇静状态下,分别行ABR和ASSR测试.ABR为click刺激声,刺激率为11.1次/s,记录ABR的Ⅱ渡反应阈值.ASSR载波频率(CF)为0.5、1、2、3、4、6 kHz,调制频率(MF)为154 Hz,记录各载频的反应阅值.结果 正常豚鼠ASSR反应阈值高于ABR反应阈值,CF:0.5.4 kHz时.ABR与ASSR阈值间有统计学差异(P<0.01);CF=6 kHz时,两阈值间无统计学差异(P>0.05).结论 正常豚鼠ABR与ASSR阈值间存在较大差值,但ABR与6 kHz的ASSR阈值间无显著差异.故对豚鼠进行听阈评估时,要注意两者间由于ASSR载波频率不同所引起的差异.     

水合氯醛对豚鼠听性脑干反应的影响

目的 探讨水合氯醛麻醉对成年豚鼠听性脑干反应检测的影响.方法 分别在清醒状态(w aking state,W)及水合氯醛(chloral hydrate,CH)麻醉状态下对20只健康成年雄性白色豚鼠进行短声(click)诱发的听性脑干反应(auditory brainstem response,ABR)检测,以引出率最高的波来判断反应阈值,比较两种状态下90 dB peSPL刺激声强下ABR各波的潜伏期、波间期及不同强度下的Ⅱ 、Ⅲ 、Ⅳ波振幅及引出率.结果 20只豚鼠水合氯醛麻醉状态与清醒状态下ABR反应阈分别为25.50±2.76、28.5±3.66 dB peSPL,差异无统计学意义(P>0.05).水合氯醛麻醉状态下ABR各波潜伏期较清醒状态均延长,Ⅲ 、Ⅳ 、Ⅴ波差异有统计学意义(P<0.05),而Ⅰ 、Ⅱ波差异无统计学意义(P>0.05);水合氯醛麻醉状态下Ⅰ-Ⅴ 、Ⅲ-Ⅳ 、Ⅳ-Ⅴ波间期较清醒状态下延长(P<0.05),而Ⅰ-Ⅱ 、Ⅱ-Ⅲ波间期差异无统计学意义(P>0.05);水合氯醛麻醉状态和清醒状态均显示波Ⅱ振幅及引出率最高;水合氯醛麻醉状态波Ⅱ 、Ⅲ振幅在高强度刺激声时较清醒状态高,而波Ⅳ振幅较清醒状态低(P<0.05).结论 水合氯醛麻醉及清醒状态下豚鼠ABR反应阈无明显差异,但水合氯醛麻醉会使豚鼠ABR的波Ⅲ 、Ⅳ 、Ⅴ潜伏期明显延长,并对振幅产生影响;豚鼠ABR波Ⅱ出现率最高,可以Ⅱ波判断反应阈.     

听力筛查异常婴儿听性脑干反应测试随访

目的:对本地区听力筛查异常婴儿ABR测试结果进行分析并总结其特点。方法:对140例新生儿听力筛查异常者在3个月龄左右时进行第1次ABR测试,第1次ABR诊断异常者于6个月龄左右进行第2次ABR测试,并进行统计分析。结果:140例婴儿经第1次ABR诊断,65例正常(46.43%);75例有单耳或双耳听力障碍(53.57%),其中单耳17.14%,双耳36.43%,以轻度听力障碍为最多,占27.14%,极重度听力障碍亦不少见,占14.29%;男、女听力障碍的发病率差异无统计学意义(P>0.05),高危儿与非高危儿发生听力障碍例数经比较差异无统计学意义(P>0.05),重度以上听力损失例数高危儿与非高危儿比较差异有统计学意义(P<0.05)。第2次ABR复诊38例,正常8例,总正常率52.14%(73/140);16例轻度听力障碍中10例转为正常或好转、6例无变化或加重,3例中度听力障碍中1例好转、2例无变化,9例重度听力障碍中3例好转、3例无变化、3例加重,10例极重度听力障碍中9例无变化或加重,1例脑瘫儿极重度听力障碍转归为正常;非高危儿听力好转情况显著高于高危儿(P<0.05)。结论:应全面开展新生儿听力筛查,重点关注高危儿听力损失;重度以下听力障碍具有可变性,对脑瘫等特殊儿童听力情况评估应慎重;应尽快建立健全的追踪、随访和管理体系。     

颈上神经节切除对豚鼠耳蜗血流及听性脑干反应阈的影响

目的研究豚鼠颈交感神经节对耳蜗血流及听觉生理功能的调节作用。方法在正常豚鼠单侧耳蜗螺旋蜗轴动脉局部滴加逆行追踪剂辣根过氧化物酶(horseradishperoxidase,HRP),观察双侧交感颈上神经节、星状神经节内的阳性神经元分布;建立单侧颈上神经节切除模型,观察术后不同时间点双侧耳蜗血流、听性脑干反应的情况;建立单侧颈上神经节切除后噪声性听损伤模型,观察颈上神经节切除对噪声损伤导致的听觉阈移是否有保护作用。结果耳蜗螺旋蜗轴动脉局部给予逆行追踪剂后同侧颈上神经节内可见阳性神经元;单侧颈上神经节切除1周后,术侧耳蜗底回血管纹处血流较对侧升高,听性脑干反应阈值无明显变化;颈上神经节切除对噪声导致的听损伤有一定的保护作用。结论交感颈上神经节切除对豚鼠耳蜗血流及听觉生理功能有一定的影响。     

正常新生儿听性脑干反应测试结果分析

目的　分析新生儿听性脑干反应(auditorybrainstemresponses,ABR)的基本特征,为国内开展新生儿ABR检测及听力筛选提供依据。方法　对80名正常新生儿(160耳)的ABR测试结果进行分析,并与正常听力青年人测试结果进行比较。结果　130dBpeSPL强度短声刺激下,正常新生儿波Ⅰ、波Ⅲ、波Ⅴ的检出率均为100%。波Ⅴ反应阈为61.94±6.87dBpeSPL,显著高于正常听力青年人。新生儿波潜伏期和波间期均较正常听力青年人延长,波间期Ⅲ-Ⅴ/Ⅰ-Ⅲ比值显著低于正常听力青年人。结论　70dBpeSPL短声是较为适宜的新生儿ABR听力筛选的声刺激;性别及左、右耳差异不影响新生儿ABR筛选;新生儿听觉通路存在一个不断完善的成熟过程,但其脑干上、下部的发育并不是完全同步的。     

无听力损失耳呜患者听性脑干反应检测及意义

目的：探讨无听力损失耳鸣患者听性脑干反应（ＡＢＲ）的检测及意义。方法：利用颌部乳突部引导方法启示ＡＢＲ,将无听力损失耳鸣患者的ＡＢＲ与听力正常青年人进行对比观察。结果：耳呜患者１波潜状期延长占５１．６％,３波占２０．９％,５波占１７．９％。结论：虽然此类耳鸣患者未发现听阈提高,已有部分患者发生于耳蜗性损害。     

正常新生豚鼠听性脑干反应的时域和频域特性

本文对正常新生豚鼠听性脑干反应（ＡＢＲ）时域和频域特性进行了研究。结果表明：正常新生豚鼠ＡＢＲ的反应阈为２２±４ｄＢｎＨＬ（０ｄＢｎＨＬ＝１７ｄＢＳＰＬ），约比正常成年豚鼠ＡＢＲ的反应阈高１０ｄＢｎＨＬ；正常新生豚鼠波Ⅲ潜伏期、Ⅰ─Ⅲ波间期均明显长于正常成年豚鼠（Ｐ＜０．０１），而波Ⅰ潜伏期无显著性差异（Ｐ＞０．０５）；潜伏期─强度函数曲线的斜率大于正常成年豚鼠；功率谱表明，与正常成年豚鼠相比较，０～２００Ｈｚ、５１０～９００Ｈｚ频段谱能量有显著性差异（Ｐ＜０．０５、Ｐ＜０．０１）。     

高功率微波辐射后豚鼠听性脑干反应阈值的变化

目的本研究运用同一波段、不同功率的微波对豚鼠照射,观察豚鼠微波辐射前后听力的变化。方法选取听力正常的SPF级雄性Hartley豚鼠,随机分为对照组、30m W/cm~2组100m W/cm~2组,于辐射前、辐射后即刻、3天、7天、14天测定听性脑干反应阈值。结果100 m W/cm~2组辐射后ABR阈值升高,即刻、3天、7天、14天ABR阈移与对照组差异有显著统计学意义(P<0.05);30m W/cm~2组阈移与对照组差异无统计学意义(P>0.05)。结论本实验条件下的结果表明,高功率微波辐射可导致豚鼠ABR阈值升高,但损伤作用与辐射的功率有关。     

The effect of gap-marker spectrum on gap-evoked auditory response from the inferior colliculus and auditory cortex of guinea pigs

The objective of this study is to verify the effects of gap marker spectrum on gap-evoked auditory responses. The gap-evoked potentials were recorded using electrodes implanted in the inferior colliculus (IC) and auditory cortex (AC) of guinea pigs. The gap markers were noise bursts in four frequency bands (500–8?000?Hz, 500–16?000?Hz, 500–32?000?Hz, and 16?000–32?000?Hz), and were tested at three sound levels. The onset response to the post-gap marker was measured to obtain the gap response threshold, and to establish input-output functions for latency and amplitude. Similar to previous behavioural studies, it was found that the gap-response threshold decreased with increasing marker bandwidth. This change was more significant at the cortical level in which the averaged gap-threshold decreased by approximately 2?ms with the bandwidth change. However, the gap threshold in the high frequency region (16?000–32?000?Hz) was comparable to that of the low frequency region (500–16?000?Hz). These results suggest that the total bandwidth of all auditory channels that are recruited determine the temporal resolution measured in gap-evoked potentials.

Sumario

El objetivo de este estudio es verificar los efectos del espectro de marcadores de brecha sobre las respuestas auditivas evocadas por una brecha. Se registraron los potenciales evocados por brecha utilizando electrodos implantados en el colículo inferior (IC) y la corteza auditiva (AC) de cobayos. Los marcadores de brecha fueron bursts de ruido en cuatro bandas de frecuencia (500–8000?Hz, 500–16?000?Hz, 500–32?000?Hz and 16?000–32?000?Hz), y se evaluaron a tres niveles sonoros. Se midió la respuesta de inicio del marcador post-brecha para obtener el umbral de respuesta de brecha, y establecer las funciones de ingreso-salida para latencia y amplitud. Al igual que en estudios conductuales previos, se encontró que el umbral de respuesta de brecha disminuyó con el incremento de los anchos de banda del marcador. Este cambio fue más significativo a nivel cortical en donde el umbral promediado de brecha disminuyó en aproximadamente 2 mseg con el cambio de ancho de banda. Sin embargo, el umbral de brecha en la región de alta frecuencia (16?000–32?000?Hz) fue comparable al umbral de la región de baja frecuencia (500–16?000?Hz). Estos resultados sugieren que el ancho de banda total de todos los canales auditivos reclutados determina la resolución temporal medida en los potenciales evocados por brecha.     

Auditory brain-stem responses in guinea pigs following middle ear implantation of Ceravital

Summary The effects on auditory function caused by implantation of the bioactive glass ceramic Ceravital in the middle ear of guinea pigs was investigated. Auditory brain-stem responses (ABR) were used to measure hearing function. A threshold shift due to a conductive hearing loss was observed immediately post-operatively. This threshold shift increased towards the 20th post-operative day and improved thereafter. Surgical manipulation of the middle ear and biochemical reactions between the Ceravital granules and the middle ear wall may have contributed respectively to the immediate and late temporary ABR threshold shift recorded. However, cochlear function was not affected by middle ear implantation of Ceravital. These results correlate well with morphological studies of Ceravital implanted in the middle ear and give further support to the safe use of Ceravital as an implantation material in middle ear reconstructive surgery. Offprint requests to: D. Zikk, Department of Otorhinolaryngology, Tel Aviv Sourasky Medical Center, Ichilov Hospital, 6 Weizman St., Tel Aviv 64239, Israel     

The effect of noise-induced sloping high-frequency hearing loss on the gap-response in the inferior colliculus and auditory cortex of guinea pigs

Gap detection has been used as an evaluation tool for temporal processing in subjects with sensorineural hearing loss (SNHL). However, the results from other reports are varied making it difficult to clearly define the impact of SNHL on the temporal processing ability of the auditory system. Specifically, we do not know if and how a high-frequency hearing loss impacts, presumably through off-channel interaction, the temporal processing in low-frequency channels where hearing sensitivity is virtually normal. In this experiment, gap-evoked responses in a low-frequency band (0.5–8 kHz) were recorded in the inferior colliculus (IC) and auditory cortex (AC) of guinea pigs through implanted electrodes, before and after a slopping high-frequency hearing loss, which was induced by over-stimulation using a 12-kHz-tone. The results showed that the gap thresholds in the low-frequency region increased gradually and became significantly higher 8 weeks after the induced high-frequency hearing loss. In addition, the response latency was slightly increased in the IC but this was not true for the AC. These results strongly indicate that a high-frequency hearing loss exerted an off-channel impact on temporal processing in the low-frequency region of the auditory system.     

高速率电刺激对豚鼠听神经兴奋性的影响

目的：评估高速率电刺激对豚鼠听神经兴奋性的影响。方法：切开受试豚鼠圆窗膜,标准电极插入鼓阶大约4mm,两个靠近蜗尖的电极作为刺激电极,切开圆窗用压碎的颞肌封住。随机选择一耳为刺激耳,另一耳则为对照耳,均安装上标准电极,刺激电极在整个测试过程中保持不动。在保持刺激强度处在临床正常水平[电刺激诱发听觉脑干电位(EABR)阈值上6dB]情况下,用200(n=14)、400(n=10)、1000(n=11)、2000(n=10)脉冲数／s(PPS)四种不同的电刺激速率急性刺激45只听力正常豚鼠鼓阶内电极2h,记录急性刺激前、后3h内EABR的阈值和Ⅰ波幅值,比较急性刺激前、后EABR的Ⅰ波幅值的变化。结果：急性刺激电流强度固定在临床正常水平(EABR阈上6dB),急性刺激后EABR的Ⅰ波幅值同急性刺激前相比,采用200PPS刺激速率平均约升高20％;400PPS约升高9％;1000PPS约升高7％;2000PPS约升高30％。结论：在刺激电流强度为阈上6dB的情况下,人工耳蜗言语编码策略如果应用1000、2000PPS高速率电刺激不会导致听神经的兴奋性下降。此实验为临床上研制新的人工耳蜗采取高刺激速率语音信号处理方案提供了依据。     

Frequency-dependence of early auditory evoked responses in the guinea pig

Summary Neural auditory responses in the guinea pig, monitored by surface electrodes (brain stem potentials and frequency-following responses) and by electrodes at the round window, were analyzed for evidence of frequency dependence in the range from 500 Hz to 15 kHz. The characteristics of the brain stem potentials and frequency-following responses with stimuli near threshold intensity for frequencies below 2 kHz indicate that this activity derives from the excitation of apical regions of the basilar membrane. The same interpretation applies to the potentials recorded at the round window. Comparison of the responses seen with surface electrodes and those appearing at the round window reveals that the broad potential P_I of the brain stem response to low-frequency stimuli corresponds to the compound action potential, while the frequency-following responses correspond to phase-locked responses in the acoustic nerve.     

Auditory brain-stem response and hearing threshold in cerebellopontine angle tumours

Summary The auditory brain-stem responses (ABR) in 19 patients with confirmed cerebellopontine angle tumours are evaluated in relation to the hearing threshold as obtained by pure-tone audiometry. ABR pathological alterations, in terms of either absence or presence of components, appear to relate to the suprathreshold stimulus intensity and to match the changes which can be observed in subjects with normal hearing, when stimulated at the equivalent suprathreshold intensity. Of the diagnostic indexes considered (I-V interval, IT₅, V), IT₅ and V could be evaluated in the largest patient population. They may be used in combination to enhance their sensitivity in retrocochlear lesion detection.     

外淋巴“枯竭“状态对听神经兴奋性影响

目的 通过记录电刺激诱发听觉脑干电位(EABR)阈值变化搞清楚内耳外淋巴“枯竭”状态对听神经兴奋性影响。方法 在手术显微镜帮助下,小心把标准刺激电极沿蜗轴插入鼓阶约4mm,用压碎的肌肉轻轻封住圆窗口。然后用波宽为50μs/phase、刺激速率为30次/秒电荷平衡双相脉冲电流刺激受试动物鼓阶内的靠近蜗尖的电极对(1/2),记录两次EABR阈值,取均值。然后把明胶海绵做成直径约为1mm,长约为4cm小的圆柱形,把一端放入前庭阶持续吸干外淋巴,直到显微镜下见鼓阶外淋巴消失,模拟外淋巴“枯竭”状,用以上电刺激参数再次记录电极对(1/2)的EABR阈值两次,取均值。比较前后两次EABR阈值的变化(t检验)。结果 耳蜗外淋巴“枯竭”状态时测试到的EABABR阈值0.63±0.11mA较充满外淋巴时0.27±0.08mA明显升高(P<0.001)。结论 EABR阈值升高说明耳蜗鼓阶外淋巴呈现“枯竭”状态时听神经兴奋性明显下降,临床上少数重聋或者全聋患者耳蜗外淋巴呈现“枯竭”状态,推测其电子耳蜗植入临床效果可能较耳蜗鼓阶内外淋巴正常患者差。     

听性稳态反应与听性脑干反应阈值的比较

目的:通过比较同一组聋儿听性脑干反应(ABR)和听性稳态反应(ASSR)的反应阈值,对ASSR的临床应用价值作出评价。方法:分别记录65例年龄在2.5个月~5.5岁聋儿的ABR及ASSR结果并进行比较及相关分析。结果:本组聋儿ABR反应阈值左右耳分别为(85.82±12.39)和(82.70±14.93)dB nHL;ASSR 4个测试频率的反应阈值左耳为(86.91±16.70)(、90.32±16.11)、(91.02±16.58)、(89.80±17.08)dB HL,右耳为(85.15±18.16)(、89.32±17.76)(、90.41±18.87)(、85.15±17.03)dB HL。ASSR 4个测试频率的反应阈值与ABR结果的相关系数分别为左耳0.622、0.721、0.757、0.714和右耳0.613、0.732、0.795、0.739。结论:ASSR与ABR测试结果有显著的相关性,而ASSR所获得的是分频资料,因此这种测试方法有较高的临床应用价值。     

模拟失重条件下飞船内噪声对豚鼠耳蜗形态与功能的影响

目的探讨模拟失重条件下,飞船内稳态噪声对豚鼠耳蜗形态与功能的影响。方法32只豚鼠随机分为单纯失重组16只、失重＋稳态噪声组16只。后肢悬吊法模拟失重,暴露于模拟飞船内在天飞行段的噪声环境,共5天。实验前、实验结束后即刻和实验结束后3天测试脑干诱发电位（ABR）阈值,取耳蜗标本行扫描电镜和透射电镜观察。结果实验组实验结束后即刻ABR阈值较实验前及实验结束后3天均增高（P〈0.01）;实验结束后3天ABR阈值较实验前高（P〈0.05）;实验结束后即刻及实验结束后3天失重＋稳态噪声组ABR阈值均较单纯失重组高（P〈0.01）。扫描电镜观察实验组实验结束后即刻耳蜗内、外毛细胞均受损。实验结束后3天,单纯失重组少数耳蜗各回内、外毛细胞的损伤程度比实验结束即刻加重;失重＋稳态噪声组耳蜗各回内毛细胞损伤较实验结束即刻重,外毛细胞损伤较实验结束即刻轻。实验组各时间段内毛细胞的损伤均重于外毛细胞,自第一回至第四回毛细胞损伤逐渐加重。透射电镜观察实验组耳蜗毛细胞及神经节细胞均可见空泡样改变,线粒体分布减少,细胞核固缩,可见细胞凋亡和细胞坏死两种细胞死亡现象。结论失重及失重＋稳态噪声均可造成豚鼠耳蜗形态和功能损伤,后者造成的损伤更重。失重对耳蜗毛细胞损伤以内毛细胞为重,损伤从底回至顶回逐渐加重。实验结束后3天较实验后即刻的听功能有所恢复但内毛细胞损伤加重。