3～4月龄及5～6月龄婴儿听性脑干反应的正常值分析

目的观察正常婴儿听性脑干反应(ABR)潜伏期及阈值正常值范围,为早期干预治疗提供依据。方法应用美国ICS CHARTR诱发电位仪对40例(80耳)听力正常的婴儿和20例听力正常成人进行ABR检测,根据年龄分为A组(3~4月龄)、B组(5~6月龄)、对照组。建立不同月龄婴儿ABR正常值范围,讨论性别、耳别、月龄对测试结果的影响及阈值测定的临床应用。结果80dB nHL短声刺激下,A组A easeBR波Ⅰ、Ⅲ、Ⅴ潜伏期的正常值范围分别是:(1.52±0.19)m s、(4.20±0.20)m s、(6.34±0.26)m s;B组ABR波Ⅰ、Ⅲ、Ⅴ潜伏期的正常值范围分别是:(1.50±0.09)m s、(4.05±0.16)m s、(6.16±0.25)m s;对照组ABR波Ⅰ、Ⅲ、Ⅴ潜伏期的正常值范围分别是:(1.43±0.10)m s、(3.63±0.15)m s、(5.50±0.16)m s。随着月龄的增长,婴儿各波的潜伏期(PL)和波间期(IPL)均缩短;但6月龄时仍未达成人水平。A、B两组各波的潜伏期及波间期与对照组比较差异均有统计学意义(P0.05);A组与B组比较Ⅲ、Ⅴ波潜伏期及Ⅰ-Ⅲ、Ⅰ-Ⅴ波间期差异具有统计学意义(P0.05)。女婴潜伏期和波间期短于男婴(A组内Ⅰ-Ⅲ波间期除外),A组内男女间Ⅴ波潜伏期差异具有统计学意义(P0.05);B组内男女Ⅲ、Ⅴ波潜伏期及Ⅰ-Ⅴ波间期差异有统计学意义(P0.05);各组内左右耳差异无统计学意义(P0.05)。各月龄组及正常成人ABR反应阈差异无统计学意义。结论建立不同月龄婴儿ABR潜伏期及阈值正常值标准,为听损伤的早期诊断和随访监测提供可靠依据。     

声诱发短潜伏期负电位豚鼠的内耳铺片研究

目的 在耳毒性损伤的豚鼠模型上诱发声诱发短潜伏期负电位( acoustically evoked short latency negative response,ASNR),通过内耳铺片观察ASNR豚鼠的基底膜球囊、椭圆囊及半规管壶腹的组织形态学特点,验证豚鼠ASNR的责任终器.方法 将45只健康豚鼠按随机数字表法分为2组,健康对照组15只(30耳),药物致聋组30只(60耳).致聋组给药(硫酸卡那霉素+利尿酸)致聋7～10d后,行听觉脑干反应(ABR)测试,根据ASNR引出情况进一步分为ASNR组和非ASNR组.三组豚鼠断头取颞骨,解剖显微镜下取出基底膜、球囊斑、椭圆囊斑和壶腹嵴,通过显微镜观察毛细胞数目和形态变化.结果 致聋组有27只动物(54耳)完成测试,其中45耳达到重度感音神经性聋,19耳引出ASNR(35.2％),阈值为110～125 dBSPL,平均阈值(121.7±4.5)dBSPL,潜伏期1.80～2.08 ns,平均潜伏期(1.93±0.07)ms.铺片观察显示,基底膜、球囊、随圆囊、壶腹嵴毛细胞密度按正常对照组、ASNR组、非ASNR组依次减低,毛细胞损伤程度依次加重.ASNR组球囊微纹区、周边区毛细胞密度与对照组差异无统计学意义(P值均＞0.05);其他各组的相应比较,差异均有统计学意义(P值均＜0.05).结论 豚鼠ASNR的责任终器是球囊,而不依赖于耳蜗、椭圆囊及半规管功能.     

金纳多减轻顺铂耳毒性的超氧化物歧化酶检测及扫描电镜观察

目的 观察银杏叶提取物一金纳多(Extract ofGinkgo Biloba Leaves Injection,EGB)对抗顺铂(Cisplatin,CDDP)耳毒性的作用。方法 将24只豚鼠随机分为CDDP组、EGB CDDP组及对照组,采用听性脑干反应(auditory brainstem response,ABR)、血清超氧化物歧化酶(superoxide dismutase,SOD)活性和丙二醛(MDA)含量、光镜及扫描电镜技术,观察用药前后各指标的变化。结果CDDP组动物ABR阈值较其它两组明显升高(P<0.01),其余两组间差异亦有显著性(0.010.05)。血清MDA含量以CDDP组升高最显著(P<0.01),EGB CDDP组较对照组略有升高,没有显著性差异(P>0.05)。耳蜗扫描电镜显示EGV CDDP组较CDDP组毛细胞受损程度明显减轻。结论EGB可有效减轻CDDP的耳毒性作用。     

分泌性中耳炎患儿听性脑干反应的应用及特征

目的 通过比较分泌性中耳炎(otitis media with effusion, OME)患儿鼓膜置管术前、后听性脑干反应(auditory brainstem response, ABR)的变化,探讨ABR测试在儿童分泌性中耳炎诊治中的临床应用价值.方法 对50例(100耳)分泌性中耳炎患儿行鼓膜置管术前进行ABR测试,其中有30例(60耳) 术后再次行ABR测试,并与50例(100耳)正常对照组儿童进行比较;另外将该30例(60耳)患儿根据鼓室分泌物黏稠度分两组,分泌物黏稠组16例(32耳),分泌物稀薄组14例(28耳),将两组ABR波Ⅴ阈值结果进行比较.结果 50例(100耳)分泌性中耳炎患儿术前ABR波Ⅴ阈值及波Ⅰ潜伏期均正常者占13%,漏诊率为13%;波Ⅴ阈值正常占41%,轻度异常52%,中度异常7%;波Ⅰ潜伏期正常19%,72%波Ⅰ潜伏期延长,9%出现波Ⅰ缺失.术前OME组患儿的ABR波Ⅰ、Ⅲ、Ⅴ各波潜伏期比正常儿童延长,阈值升高,差异有显著统计学意义(P＜0.01).Ⅰ-Ⅲ、Ⅰ-Ⅴ波间期缩短,与正常组比较差异有显著统计学意义(P＜0.01).术后ABR波Ⅴ阈值及波Ⅰ潜伏期均正常者占46.7%;波Ⅴ阈值正常占70.5%,轻度异常29.5%;波Ⅰ引出率100%,潜伏期正常占50.2%;OME组中术前、术后ABR各波潜伏期、波Ⅴ阈值比较差异有显著统计学意义(P＜0.01),各波波间期比较无差异,术后听力有明显改善,但与正常组比较部分患儿波Ⅴ阈值仍高,波Ⅰ、Ⅲ潜伏期仍延长,Ⅰ-Ⅲ、Ⅰ-Ⅴ波间期缩短(P＜0.05);分泌物黏稠组波Ⅴ阈值较稀薄组高.结论 单用ABR作为诊断OME的依据是有欠缺的,但大部分患儿可以通过该检查进行听力损失的评估,以了解鼓膜置管术后的听力状况及恢复程度.     

幼年和成年豚鼠失匹配负波反应的特性

目的探讨豚鼠失匹配负波(mismatch negativity,MMN)的反应特点,观察声刺激频率和强度对不同年龄豚鼠MMN潜伏期和振幅的影响,建立测试动物MMN的方法。方法选择正常幼年和成年豚鼠各10只(20耳),在麻醉状态下行MMN和听觉脑干反应(auditory brainstem response,ABR)测试,分别比较两组豚鼠听觉功能差异。结果频率和强度差异诱发MMN成年鼠的潜伏期明显短于幼鼠,潜伏期差异皆有统计学意义(两者P均<0.05),而振幅差异无统计学意义(P>0.05)。两组豚鼠ABR除Ⅰ～Ⅲ波间期差异有显著性(P=0.04),其余各波潜伏期、波间期和阈值差异均无统计学意义(P>0.05)。结论豚鼠存在与人相似的MMN波形,并随年龄有一个发育、分化和成熟的过程,可作为研究MMN神经生理机制的实验动物。与ABR比较,MMN在检测听觉中枢功能的敏感性上更具有优势。     

NGB基因转染拮抗庆大霉素耳毒性作用的实验研究

目的验证阳离子脂质体介导脑红蛋白(neuroglobin,NGB)基因转染对庆大霉素致豚鼠耳毒性的保护作用。方法将ABR反应阈均不超过40dB SPL的120只健康花色豚鼠随机分为5组,每组24只:Ⅰ组:空白对照组;Ⅱ组:人工外淋巴液对照组(经左耳注入人工外淋巴液);Ⅲ组:人工外淋巴液实验组(经左耳注入人工外淋巴液后肌肉注射庆大霉素);Ⅳ组:空质粒转染组(经左耳注入空质粒pEGFP-C1后肌肉注射庆大霉素);Ⅴ组:NGB基因转染组(经左耳注入pEGFP-NGB后肌肉注射庆大霉素),庆大霉素均经后腿肌肉注射120mg.kg-1.d-1,共给药14天。停止给药后喂养14天,各组均行ABR检测,耳蜗基底膜铺片、免疫组化观察各组豚鼠耳蜗基底膜毛细胞形态学及NGB蛋白表达的变化。结果给药后Ⅰ组ABR反应阈平均为37.22dB SPL(左耳)和36.94dB SPL(右耳),Ⅱ组阈值平均为37.22dB SPL(左耳)和37.50dB SPL(右耳),Ⅲ组阈值平均为119.44dB SPL(左耳)和122.22dB SPL(右耳);Ⅳ组阈值平均为119.72dB SPL(左耳)和120.83dB SPL(右耳);Ⅴ组阈值平均为83.89dB SPL(左耳)和100.56dB SPL(右耳)。Ⅴ组ABR反应阈较Ⅰ组和Ⅱ组显著升高(P<0.05),较Ⅲ组和Ⅳ组显著降低(P<0.05)。Ⅴ组中手术耳ABR反应阈较非手术耳降低(P<0.05)。耳蜗基底膜铺片示Ⅰ组和Ⅱ组内外毛细胞排列整齐,无缺失,Ⅲ组和Ⅳ组内外毛细胞极少量残存,其中ABR阈值大于135dB SPL的豚鼠耳蜗毛细胞几乎消失殆尽,Ⅴ组毛细胞部分缺失,且主要是外毛细胞;免疫组织化学染色示Ⅴ组耳蜗毛细胞NGB蛋白表达量较其余各组均显著增高(P<0.05),其余各组几乎均未见明显阳性表达。结论本研究成功验证了阳离子脂质体介导NGB基因转染对庆大霉素致豚鼠耳毒性具有有效的保护作用。     

卡那霉素联合速尿致聋豚鼠的Math1基因治疗

目的 观察卡那霉素和速尿联合致聋豚鼠耳蜗鼓阶导入Math1基因后的形态学及功能改变,探讨Mathl基因治疗药物中毒性耳聋的可行性.方法 健康成年豚鼠经硫酸卡那霉素(500 mg/kg)和速尿(50 mg/kg)联合致聋,将听性脑干反应(ABR)反应阈＞95 dB SPL的豚鼠按随机数字表法分为空白对照组(不做任何处置,3只),手术对照组(右耳单纯鼓阶钻孔,3只),人工外淋巴液组(右耳鼓阶钻孔导入人工外淋巴液,3只),单纯病毒载体组[右耳鼓阶钻孔导入携带增强型绿色荧光蛋白基因(enhanced green fluorescent protein,EGFP)的重组腺病毒(Ad.EGFP),4只]、Math1基因治疗组[右耳鼓阶钻孔导入携带Math1及EGFP基因的重组腺病毒(Ad.Math1-EGFP),6只].各组动物分别于鼓阶注射前及注射后8周时行ABR测试,结束测试后处死动物,取出耳蜗组织行扫描电镜观察.结果 各组豚鼠不同频率(4、8、16、20 kHz)短纯音ABR阈值在不同检测时间段差异均无统计学意义,组间比较差异亦无统计学意义(P值均＞0.05).除Math1基因治疗组外,其余各组右耳耳蜗各回毛细胞形态和数目与左耳(自身对照)比较无明显差别.4只Math1基因治疗组豚鼠中,有2只右耳耳蜗第三回内、外毛细胞数量明显比左耳多,其中内毛细胞排列形态较外毛细胞整齐.结论 鼓阶显微注射导入Math1基因能使部分卡那霉素和速尿联合致聋豚鼠的耳蜗毛细胞修复或再生,但其听觉功能没有改善.     

1～6岁分泌性中耳炎患儿气、骨导ABR的特征分析

目的探讨气、骨导ABR测试在儿童分泌性中耳炎诊疗中的应用价值。方法回顾性分析151例(246耳)分泌性中耳炎(OME组)和60例(120耳)正常儿童(正常对照组)气、骨导ABR检测结果。结果①OME组气导ABR波V反应阈正常59耳(23.98%),轻度异常96耳(39.02%),中度异常91耳(36.99%);ABR波Ⅰ、Ⅲ、Ⅴ潜伏期正常22耳(8.94%),各波潜伏期延长224耳(91.06%),Ⅰ-Ⅴ波间期无明显改变156耳(63.41%),Ⅰ-Ⅴ波间期缩短90耳(36.59%);波Ⅴ反应阈正常和轻度异常组Ⅰ-Ⅴ波间期无明显改变,中度异常组Ⅰ-Ⅴ波间期缩短,差异有统计学意义(P<0.05)。②OME组骨导ABR波V反应阈及35dB nHL刺激强度下各波潜伏期与对照组比较,反应阈正常195耳(79.27%),异常51耳(20.73%),反应阈异常者波Ⅰ、Ⅲ、Ⅴ潜伏期也较正常组及反应阈正常者明显延长(P<0.05)。结论大多数分泌性中耳炎儿童的气导ABR反应阈轻、中度异常但骨导ABR反应阈正常,少数患儿气导ABR反应阈中度异常且骨导ABR反应阈轻度异常。     

90岁以上老年性聋患者的听性脑干反应

目的分析90岁以上老年性聋患者听性脑干反应(ABR)的特征。方法对14例90岁以上老年性聋患者(平均年龄91.1.4±1.3岁,26耳)进行交替短声ABR测试。听力正常人9例(平均年龄22.7±1.2岁,18耳)作为对照组。观测Ⅰ、Ⅲ、Ⅴ波的峰潜伏期(PeakLatency,PL)和Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ波间期(Inter-PeakLatency,IPL),并分别与对照组总体均数进行比较。结果总体的I波引出率和III波引出率均为76.9%(20/26),V波引出率为84.6%(22/26)。高龄老年性聋组各波PL较对照组延长。Ⅰ-Ⅲ波IPL、Ⅲ-Ⅴ波IPL、Ⅰ-Ⅴ波IPL无组间统计学差异。结论 90岁以上高龄老年性聋患者ABR波形分化较差。     

消炎痛拮抗卡那霉素耳毒作用的实验研究

为研究消炎痛对卡那霉素耳毒性的拮抗作用,本实验用听力正常的健康花斑豚鼠60只,分两组,KF组用卡那霉素450mg/kg ip及速尿60mg/kg iv,观察8天;KFI组用卡那霉素450mg/kgip,速尿60mg/kg iv,半小时后用消炎痛10mg/kg iv,第2-8天继续用消炎痛5mg/kg/d ip。两组动物于用卡那霉素、速尿前及用药后第8天检测ABR,CAP,最后一次检测听功能后,在扫描电镜及光镜下观察耳蜗螺旋器及血管纹。发现KF组ABR(Ⅲ)及CAP(N_1)声反应阈阈值较KFI组明显提高(P<0.05),耳蜗毛细胞出现程度不同的形态学变化,血管纹无水肿。结果提示,消炎痛可减轻卡那霉素的耳毒性。     

豚鼠硫酸卡那霉素急性致聋研究进展

耳聋是最为常见的健康问题之一,据估计全世界约有近十分之一人群有不同程度的听力下降〔1〕。2005年WHO估计双耳中到重度听力损失的有2.78亿。药物性聋是致聋的常见原因之一,3%～4%的发展中国家的成人和儿童以及相当数量发达国家的成人耳聋患者由药物(尤其氨基苷类抗生素)所致〔2〕。氨基苷类抗生素耳毒性的机制至今仍     

Metabolic activity of the central auditory structures following prolonged deafferentation

The goal of this work was to evaluate, using autoradiographic techniques, the effects of variable periods of deafness on resting and evoked metabolic activity in central auditory structures elicited by direct electrical cochlear nucleus (CN) stimulation. Thirty-five pigmented guinea pigs, divided into five groups, underwent acute implantation of bipolar electrodes in the CN. One group was not deafened and served as hearing controls. The other four groups were deafened using an established protocol of sequential kanamycin/ethacrynic acid treatment and were tested at 4 weeks, 9 weeks, 16 weeks, and 15 months after deafening. Threshold currents for eliciting evoked middle latency responses (EMLRs) with direct CN stimulation were not significantly different between hearing and deafened groups. Autoradiographic data showed progressive reduction of the evoked metabolic response with incremental periods of deafferentation. Nevertheless, central auditory structures remained responsive to direct electrical stimulation of the CN. These data indicate that direct CN stimulation remains capable of activating the auditory tract despite prolonged periods of deafness.     

The effect of kanamycin on experimentally induced endolymphatic hydrops

Summary In guinea pigs with endolymphatic hydrops 6 months after operation the DC potential had decreased from +80 mV to +50 mV, while the sodium activity had increased. The twofold increase in Na⁺ activity could explain the increased degree of endolymphatic hydrops. The K⁺ activity and Cl^– activity were unchanged. However, endolymphatic hydrops could be produced in kanamycin-induced deaf guinea pigs after obliteration of the endolymphatic sac and duct. The physiological data on DC potential, K⁺, and Na⁺ activity were similar to those for non-treated animals. When the animals were treated with kanamycin 6 months after the development of endolymphatic hydrops, there was no effect on the morphological and functional changes compared to controls. The data suggest that regulation of the inner ear fluid occurs independent of an intact auditory system. The effect of aminoglycoside treatment in Ménière's disease cannot be explained by an effect on endolymphatic hydrops formation.     

D-methionine (D-met) significantly reduces kanamycin-induced ototoxicity in pigmented guinea pigs

Objective: Test D-methionine (D-met) as an otoprotectant from kanamycin-induced ototoxicity and determine the lowest maximally protective D-met dose. Design: Auditory brainstem responses (ABR) were measured at 4, 8, 14, and 20?kHz at baseline and two, four, and six weeks after kanamycin and D-met administration initiation. ABR threshold shifts assessed auditory function. Following six-week ABR testing, animals were decapitated and cochleae collected for outer hair cell (OHC) quantification. Study sample: Eight groups of 10 male pigmented guinea pigs were administered a subcutaneous kanamycin (250?mg/kg/dose) injection once per day and an intraperitoneal D-met injection (0 (saline), 120, 180, 240, 300, 360, 420, or 480?mg/kg/day) twice per day for 23 days. Results: Significant ABR threshold shift reductions and increased OHC counts (p ≤0.01) were measured at multiple D-met-dosed groups starting at two-week ABR assessments. A 300?mg/kg/day optimal otoprotective D-met dose provided 34–41?dB ABR threshold shift reductions and OHC protection. Lesser, but significant, D-met otoprotection was measured at lower and higher D-met doses. Conclusions: D-met significantly reduced ABR threshold shifts and increased OHC percentages compared to kanamycin-treated controls. Results may be clinically significant particularly for multidrug-resistant tuberculosis patients who frequently suffer from kanamycin-induced hearing loss in developing countries.     

Electrophysiological study of the ototoxicity of kanamycin during development in guinea pigs

In order to test the ototoxicity of antibiotics during development, pregnant guinea pigs were intoxicated with kanamycin at different stages of gestation. Eighty newborn guinea pigs were tested electrophysiologically by recording the cochlear microphonic potential and the compound action potential from the round window in response to tone bursts and filtered clicks of various frequencies. Thirty-one animals presented antibiotic injury and showed electrophysiological changes similar to those previously described in adult mammals after kanamycin intoxication.The results suggest a relationship between the ototoxicity of kanamycin and the onset of the auditory function: cochlear potentials were mostly affected when the intoxication was performed during the last 15 days of gestation.     

Electrophysiological evaluation of chloroform-induced inner ear damage

Local placement of chloroform in either the external or the middle ear has been previously reported to induce a chemical labyrinthectomy. In order to examine the value of this effect as a research tool, we injected chloroform into the middle ears of guinea pigs and rats. Cochlear damage was assessed by electrocochleography (ECochG) and auditory brainstem response (ABR) audiometry. Both species developed complete deafness within a few hours after instillation of the chloroform. The deafness was permanent in the guinea pigs, whereas there was a partial recovery of auditory function in the rats. The survival rate of the auditory nerve fibers was estimated by measuring the ABR evoked by electrical stimulation via the scala tympani (EABR). A normal EABR recruitment pattern suggested that the main chloroform effect was located peripheral to the afferent axons. In conclusion, chloroform must be considered a severely ototoxic agent when applied locally.     

Comparison of vulnerability between avian and mammalian inner ears--electrophysiological and morphological studies]

In order to assess the vulnerability of the inner ear, auditory function and morphology of the inner ear were compared between adult budgerigars and adult guinea pigs. Budgerigars have been considered to have an excellent auditory-vocal system. Two experimental conditions were produced in each species; one by acoustic hyperstimulation (1500 Hz, 120 dBSPL) for 96 hours, the other by administration of kanamycin (200 mg/kg) for 7 weeks. Measurement of auditory evoked potentials (AEP) and observation of hair cells by electron microscopy were performed both immediately and 14 days after exposure. In the acoustic hyperstimulation experiment, AEPs of budgerigars showed less damage and better recovery than those of guinea pigs, probably because of morphological differences between the two species in hair and supporting cells. Electron microscopic observation on the budgerigars showed that a small part of the hair cell area was damaged and that regeneration of hair cells had occurred in this area 14 days after exposure. Such observations in guinea pigs revealed that outer hair cells had been damaged and replaced by supporting cells 14 days after exposure. In the kanamycin administration experiment, AEPs showed the same degree of damage and recovery in both species. This suggests that blood supply and drug transport to the inner ear are almost the same although the structure of the inner ear differs markedly between the two species. Electron microscopic observation did not show an apparent regeneration of hair cells 14 days after administration in the budgerigars. Guinea pigs had a tendency to show progressive damage of both auditory function and inner ear morphology even after the cessation of administration. Regeneration of hair cells in the budgerigar differed under both experimental conditions, suggesting that there is a difference in the mode of auditory disturbance between acoustic hyperstimulation and administration of kanamycin. In conclusion, resistance to acoustic hyperstimulation is higher in the avian inner ear than in the mammalian inner ear, while resistance to administration of kanamycin does not differ significantly between the two species.     

卡那霉素和速尿联合用药后的毛细胞死亡*

目的观察卡那霉素和速尿联合用药后豚鼠耳蜗毛细胞的死亡时程和方式.方法选用健康成年白色红目豚鼠,雌雄不限,随机分成健康对照组和药物致聋后6 h、9 h组(实验组),每组5只.实验组在选取的时间点完成听性脑干反应(ABR)检测后行耳蜗基底膜铺片、PI荧光染色,共聚焦显微镜下观察毛细胞.对照组不做处理.结果实验组半数豚鼠致聋(ABR阈值>95 dB SPL),致聋豚鼠耳蜗可见外毛细胞核固缩和核肿胀,与给药6 h组相比,给药9 h组外毛细胞核肿胀数目增多.检测给药6 h组和9 h组豚鼠末端脱氧核苷酸转移酶介导的dUTP缺口末端标记物(terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling,TUNEL),没有观察到阳性着色细胞.正常对照组所有豚鼠ABR正常,其耳蜗各回毛细胞没有出现毛细胞核固缩或者核肿胀.结论卡那霉素和速尿联合用药后数小时即可导致豚鼠耳蜗毛细胞死亡,毛细胞损害为两种类型,即坏死和凋亡.     

纯中药制剂复聪汤对庆大霉素致聋豚鼠耳蜗毛细胞修复再生的实验研究

目的观察纯中药制剂对庆大霉素致聋动物和耳蜗毛细胞的修复再生作用。方法选用73只健康青年豚鼠,行听力学检查后,53只动物连续肌肉注射庆大霉素(80mg.kg-1.d-1)24～30天致聋(GM组),其间死亡8只,剩余45只随机分成中药治疗组(25只)和致聋后对照组(20只),中药治疗组给予纯中药制剂"复聪汤Ⅰ号"口服液和"复聪汤Ⅱ号"滴耳液治疗,致聋后对照组同法给予生理盐水。另外20只豚鼠作为正常对照组,每天肌肉注射等量生理盐水。在治疗30、60和90天后对GM组两组动物分别行ABR、DPOAE检测,同时,每一时间点处死6只动物,左侧耳蜗行扫描电镜观察,右侧耳蜗铺片行光镜观察和毛细胞计数。结果实验前所有豚鼠的听功能正常;连续注射庆大霉素30天后,GM组豚鼠ABR反应阈值上升到50～80dB SPL,DPOAE幅值降低,光镜和电镜下表现为耳蜗毛细胞纤毛断碎、倒伏、融合和消失,多处毛细胞表皮板肿胀、突起和疱疹样变性,或毛细胞被完全挤出网状板,基底回和第三回耳蜗毛细胞严重消失;中药治疗30天后,80%的耳聋豚鼠的ABR反应阈恢复到30～50dB SPL,DPOAE幅值明显提高;耳蜗铺片和电镜观察显示耳蜗毛细胞数目有一定恢复,组织结构有修复现象,扫描电镜可见再生毛细胞仅出现少量纤毛,而致聋后对照组未发现此种现象;治疗60天后,耳蜗毛细胞数目明显增多,Corti器的毛细胞区有大量的增殖细胞出现,扫描电镜可见成小束的新生纤毛出现在毛细胞缺失部位,同时支持细胞大量增殖;治疗90天后,再生的静纤毛束已基本形成,尤其是耳蜗基底部位的毛细胞明显增多,听功能基本正常。结论纯中药制剂复聪汤对庆大霉素致聋豚鼠耳蜗毛细胞有一定的修复和再生作用。     

Electrophysiological evaluation of chloroform-induced inner ear damage

Summary Local placement of chloroform in either the external or the middle ear has been previously reported to induce a chemical labyrinthectomy. In order to examine the value of this effect as a research tool, we injected chloroform into the middle ears of guinea pigs and rats. Cochlear damage was assessed by electrocochleography (ECochG) and auditory brainstem response (ABR) audiometry. Both species developed complete deafness within a few hours after instillation of the chloroform. The deafness was permanent in the guinea pigs, whereas there was a partial recovery of auditory function in the rats. The survival rate of the auditory nerve fibers was estimated by measuring the ABR evoked by electrical stimulation via the scala tympani (EABR). A normal EABR recruitment pattern suggested that the main chloroform effect was located peripheral to the afferent axons. In conclusion, chloroform must be considered a severely ototoxic agent when applied locally.Dr. Hu Ke is on academic leave from the Department of Otolaryngology, Peking Union Medical College Hospital, Beijing, China.Supported by Pacific Otolaryngology Foundation and Medical Research Council, Canada