应用微波技术行后半规管阻塞术的实验研究

目的 :探讨应用微波技术行后半规管阻塞术的可行性。方法 :应用微波技术对 2 0只豚鼠行后半规管阻塞术 ,观察术前、术后豚鼠眼震电图 (ENG) ,听性脑干反应 (ABR)及形态学的变化。结果 :术后第 1天豚鼠正弦摆动刺激时术侧眼震反应减弱 ;术后第 3天双侧眼震恢复对称 ;术后 30 d冰水实验结果显示两耳能引出对称性眼震 ;术后 ABR阈值无明显改变 ;术后 6 0 d病理切片证实后半规管完全阻塞而耳蜗 Corti器和壶腹嵴正常。结论 :应用微波技术行后半规管阻塞术是对后半规管阻塞术的一种有意义的改进方法。     

三个半规管阻塞动物模型的建立

目的 旨在建立豚鼠单侧三个半规管阻塞的动物模型。方法 利用２０只豚鼠行单侧三个半规管阻塞,观察手术前后眼震电图、听性脑干反应（ａｕｄｉｔｏｒｙ ｂｒａｉｎｓｔｅｍ ｒｅｓｐｏｎｓｅｓ,ＡＢＲ）、畸变产物耳声发射（ｄｉｓｔｏｒｔｉｏｎ ｐｒｏｄｕｃｔ ｏｔｏａｃｏｕｓｔｉｃ ｅｍｉｓｓｉｏｎ,ＤＰＯＡＥ）及形态学的变化,非手术耳作对照。结果 豚鼠术后１ｄ出现自发性眼震,正弦摆动刺激单侧眼震反应消失,     

三个半规管阻塞动物模型的建立

目的　旨在建立豚鼠单侧三个半规管阻塞的动物模型。方法　利用 2 0只豚鼠行单侧三个半规管阻塞 ,观察手术前后眼震电图、听性脑干反应 (auditorybrainstemresponses,ABR)、畸变产物耳声发射 (distortionproductotoacousticemissions,DPOAE)及形态学的变化 ,非手术耳作为对照。结果　豚鼠术后 1d出现自发性眼震 ,正弦摆动刺激单侧眼震反应消失 ,侧别与术侧一致 ,术后 30d左相与右相眼震反应对称。术前微量冰水灌注 ,两耳均能引出眼震 ,术后 30d做冰水实验结果为术耳未能引出眼震 ,非术耳出现正常的眼震反应。术后ABR阈值有轻度升高 ,DPOAE反应幅度无明显改变。 8只动物病理切片证实三个半规管完全阻塞而耳蜗Corti器和壶腹嵴结构正常。结论　表明三个半规管阻塞动物模型成功 ,提示三个半规管阻塞术可望成为治疗难治性外周性眩晕的安全有效、操作相对容易的手术方法。     

豚鼠半规管阻塞术中听性脑干反应的变化

目的：观察正常豚鼠行三个半规管阻塞术中ABR反应阈值的动态变化。方法：健康白色纯种豚鼠10只，分别于术前、打开听泡、开放与阻塞各个半规管后测ABR阈值。结果：三个半规管阻塞结束后，ABR阈值平均升高6．82dB。各个半规管开窗前后ABR阈值上升较明显，而阻塞前后ABR阈值变化不明显。结论：半规管阻塞术中的听力下降是一个渐进的过程，引起听力下降的主要原因可能是外淋巴的流失，迷路受刺激并非造成听力下降的主要因素。     

三半规管阻塞与迷路切除术后前庭功能动态变化

目的：比较豚鼠三半规管阻塞与迷路切除术后前庭功能代偿的异同。材料与方法：将15只健康豚鼠分为2组，其中8只豚鼠行右侧三半规管阻塞术（triple semicircular canal occlusion,TCO)，7只豚鼠行右侧迷路切除术（labyruinthectomy,LE)，于术后一个月内观察豚鼠行为学及眼震电图（ENG）的动态变化，结果：发现术后第1天两组均出现自发性眼震，正弦摆动刺激术侧时未引出衣发性眼震，头向右侧偏斜并沿地面垂直轴向术侧旋转；LE组却出现番滚现象，术后第3，5，10，15，30天正弦摆动眼震试验，两组豚鼠术侧眼震均随时间的推移逐渐恢复，TCO组于15天左右向眼震基本恢复对称，而LE组至术后30天仅摆动幅度120，150度，180度左右向眼震基本对称，摆动幅度为60度，90度双向眼震反应差异仍有显著意义（P＜0．05），。另外，LE组有3只豚鼠仍存在头偏，结论：TCO组要比LE组动物恢复快，建立代偿和失平衡时间短。     

三半规管阻塞与迷路切除术后前庭功能动态变化

目的 :比较豚鼠三半规管阻塞与迷路切除术后前庭功能代偿的异同。材料与方法 :将 15只健康豚鼠分为 2组 ,其中 8只豚鼠行右侧三半规管阻塞术 (triple semicircular canal occlusion,TCO) ,7只豚鼠行右侧迷路切除术(labyrinthectomy,L E) ,于术后一个月内观察豚鼠行为学及眼震电图 (ENG)的动态变化。结果 :发现术后第 1天两组均出现自发性眼震 ,正弦摆动刺激术侧时未引出诱发性眼震 ,头向右侧偏斜并沿地面垂直轴向术侧旋转 ;L E组却出现翻滚现象。术后第 3、5、10、15、30天正弦摆动眼震试验 ,两组豚鼠术侧眼震均随时间的推移逐渐恢复 ,TCO组于 15天左右向眼震基本恢复对称 ,而 L E组至术后 30天仅摆动幅度 12 0°、15 0°、180°左右向眼震基本对称 ,摆动幅度为 6 0°、90°双向眼震反应差异仍有显著性意义 (P <0 .0 5 ) ;另外 ,L E组有 3只豚鼠仍存在头偏。结论 :TCO组要比 L E组动物恢复快 ,建立代偿和失平衡时间短     

豚鼠外淋巴间隙阻断术对前庭和耳蜗的影响

对１８只白色豚鼠施行单侧外半规管外淋巴间隙阻断术。术前、后观察ＡＢＲ、旋转试验，并作火棉胶连续切片光镜检查。结果提示：手术前、后ＡＢＲ阈值经统计学处理差异无显著性，而眼震持续时间差异有显著性（术后缩短），初步表明本手术可致豚鼠前庭功能降低而未明显损伤耳蜗功能。     

后半规和阻塞术对内耳功能与形态影响的实验观察

本实验对１５只豚鼠行后半规管阻塞术，术前，术后测定ＣＡＰ阈值和ＥＮＧ。并作常规火棉胶连续切片及透射电镜观察内耳形态变化。结果显示；ＣＡＰ阈值手术前，后无显著性差异；眼震持续时间，术后１周明显缩短，术后８周接近术前。术后１周，光镜下见耳蜗度圈前庭膜向蜗管内膨隆，其余结构无明显异常；     

豚鼠外淋巴间隙阻断术对前庭和耳蜗的影响

对１８只白色豚鼠施行单侧外半规管外淋巴间隙阻断术。术前、后观察ＡＢＲ、旋转试验，并作火棉胶连续切片光镜检查。结果提示：手术前、后ＡＢＲ阈值经统计学处理差异无显著性，而限震持续时间差异有显著性（术后缩短），初步表明本手术可致豚鼠前庭功能降低而未明显损伤耳蜗功能。     

单侧半规管阻塞对豚鼠前庭内侧核谷氨酸变化的影响

目的　探讨单侧外半规管阻塞造成的急性眩晕动物模型,前庭内侧核谷氨酸神经递质的变化规律。方法  在行为学验证基础上,利用活体微透析技术结合高效液相 色谱（high performance liquid chromatography,HPLC）-荧光检测方法,研究清醒状态下豚鼠前庭内侧核谷氨酸水平的变化。结果　半规管阻塞术后第1天动物出现头偏、头震及强迫环形运动等表现,上述症状于术后第4天逐渐消失。术后第1天实验组豚鼠前庭内侧核谷氨酸浓度较对照组显著提高,差异有统计学意义（t =7.4637,P <0.001）。术后第4天实验组豚鼠前庭内侧核谷氨酸浓度降低,与基线水平相比无显著差异（t =0.2447,P >0.05）。结论　豚鼠前庭内侧核谷氨酸水平显著性升高,可能与单侧半规管阻塞造成动物急性眩晕有关。     

Effects of acute infrasound exposure on vestibular and auditory functions and the ultrastructural changes of inner ear in the guinea pig]

OBJECTIVE: To define the effects of acute infrasound exposure on vestibular and auditory functions and the ultrastructural changes of inner ear in guinea pigs. METHODS: The animals involved in the study were exposed to 8 Hz infrasound at 135dB SPL for 90 minutes in a reverberant chamber. The sinusoidal pendular test (SPT), auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) were respectively detected pre-exposure and at 0(within 2 hrs), 2 and 5 day after exposure. The ultrastructures of the inner ear were observed by scanning electron microscopy. RESULTS: The slow-phase velocity and the frequency of the vestibular nystagmus elicited by sinusoidal pendular test (SPT) declined slightly following infrasound exposure, but the changes were not significant (P > 0.05). No differences in the ABR thresholds, the latencies and the interval peak latencies of I, III, V waves were found between the normal and the experimental groups, and among experimental groups. The amplitudes of DPOAE at any frequency declined remarkably in all experimental groups. The ultrastructures of the inner ear were damaged to different extent. CONCLUSION: Infrasound could transiently depress the excitability of the vestibular end-organs, decrease the function of OHC in the organ of Corti and cause damage to the inner ear of guinea pigs.     

急性次声波暴露后豚鼠位听功能及内耳超微结构的变化

目的观察次声波对豚鼠位听功能和内耳超微结构的影响。方法将豚鼠置于频率8Hz、声压级135dBSPL的次声声场中连续暴露90min。应用正弦摆动试验(sinusoidalpendulartest,SPT)、听性脑干反应（auditorybrainstemresponse,ABR）和畸变产物耳声发射(distortionproductionotoacousticemission,DPOAE)评价次声波暴露前后豚鼠前庭功能和听功能的变化,扫描电镜观察豚鼠内耳各结构表面超微形态的变化。结果次声波暴露后不同时间正弦摆动诱发的豚鼠前庭性眼震的最大慢相速度(slow-phasevelocity,SPV)和频率较次声暴露前轻微降低,但无显著性意义(P>0.05)。次声波暴露后各组动物ABR阈值较正常时略有升高,亦无统计学差异(P>0.05),各组动物ABR各波潜伏期和波间期与次声暴露前比较差异均无显著性(P>0.05);DPOAE的幅度值在各个频率段均有明显的降低(P<0.01)。扫描电镜下见各实验组动物内耳半规管壶腹嵴两囊斑及Corti器感觉毛细胞纤毛缺失、散乱、倒伏及融合,表皮板等结构均有不同程度的损伤。结论次声波对豚鼠前庭末梢感受器兴奋性可能有一过性的轻微抑制作用,但SPT无有意义改变。次声波可引起豚鼠内耳毛细胞超微结构的损伤,可导致豚鼠耳蜗外毛细胞功能明显减退,这种功能减退尚不足以引起听力的明显改变。     

Results of trapezoid rotation test in guinea pigs with unilateral endolymphatic hydrops

Obliteration of the right endolymphatic sac was performed by Kimura's method in 57 guinea pigs with normal hearing and vestibular function. However, 43 animals exhibited postoperative cerebellopontile disturbance and labyrinthitis detected by gait test, ABR test and histological examination. The remaining 14 guinea pigs were evaluated periodically by the trapezoid rotation test. Two weeks after the operation, 11 of these 14 guinea pigs exhibited prolonged right beating nystagmus based on the labyrinthine preponderance of impaired side (Lpi). In addition, endolymphatic hydrops was histological detected in the labyrinth on the operation side. A positive relation was observed between the degree of endolymphatic hydrops and the degree of Lpi. Lpi at 4 weeks after the operation was markedly lower than that at 2 weeks (P = 0.05). Therefore, the degree of Lpi was thought to be influenced by the rate of hydrops development. These results corresponded with the clinical findings that the degree of Lpi increases prior to vertiginous episodes in Meniere's patients.     

庆大霉素对豚鼠前庭功能影响的动态研究

为研究庆大霉素破坏前庭感觉上皮所致的生理功能障碍，观察庆大霉素对前庭功能影响的动态变化过程，应用正弦摆动试验和旋转试验进行动态观察。分别对白色和杂色豚鼠按每日125mg／kg体重皮下注射硫酸庆大霉素连续12天。结果示：用药7天豚鼠的前庭功能无明显改变，用药后10天出现明显的前庭功能受损，停药后5天受损程度最明显，停药14天前庭功能稍有恢复，但仍明显低下，直到停药后3个月，未见前庭功能明显改善；且杂色豚鼠前庭功能损害程度较白色豚鼠为轻。此研究为氨基式类抗生索性内耳损伤的防护和治疗提供了实验依据。     

Disappearance of click-evoked potentials on the neck of the guinea pig by pharmacological and surgical destruction of the peripheral vestibular afferent system

In order to establish an animal model of acoustically evoked vestibulo-collic reflex, the so-called vestibular evoked myogenic potential in humans, potentials evoked by loud clicks on the neck of the guinea pig were recorded using subjects whose peripheral vestibular endorgans or vestibular afferents had been damaged. Four normal control guinea pigs, four guinea pigs that received an intramuscular injection of gentamicin for 20 days (90 mg/kg/day) and five guinea pigs whose vestibular nerves were surgically sectioned were used in this study. Under general anesthesia with an intraperitoneal injection of pentobarbital sodium (40 mg/kg), auditory brainstem responses (ABRs) were recorded. Then, potentials evoked by loud clicks on the pre-vertebral muscle at the level of the third cervical vertebral bone were recorded using silver ball electrodes. As a result, a distinctive negative peak (NP) with a latency of 6-8 ms was recorded in all animals in the control group. NP was not observed in the gentamicin-administered group while ABR was preserved. After sectioning the vestibular nerve, NP was abolished while ABR was preserved. From these results, NP could be of vestibular origin. These results are in agreement with a previous report of NP using subjects whose cochlea had been damaged pharmacologically.     

Vestibular responses of normal and hydropic ears of the guinea pig to middle ear pressure application

The pressure in the middle ears of normal and hydropic guinea pig ears was increased, and nystagmographic recordings were compared. Two-month unilateral hydropic guinea pigs and normal control guinea pigs underwent pressure treatments in which pressure was introduced into the middle ear. Significantly lower pressure was needed to elicit nystagmus in hydropic ears (mean 1.00 psi or 70.3 cm H2O) compared with normal control ears (mean 1.27 psi or 89.3 cm H2O). All of the normal control guinea pigs showed fast phase nystagmus toward the pressure-applied side, while hydropic guinea pigs showed nystagmus toward the normal ear. The duration of nystagmus was slightly longer in hydropic animals than in normal control animals. The slow phase velocity was slightly higher in the hydropic guinea pigs. Histologic examination revealed that the vestibular sensory cells remained normal and that changes in the organ of Corti were similar between the hydropic ears with and without pressure treatment at equal survival times.     

Inner ear changes with intracochlear gentamicin administration in Guinea pigs

OBJECTIVES/HYPOTHESIS: Transtympanic administration of gentamicin is reported to be a useful treatment for vertigo in such conditions as Meniere's disease, and determining appropriate clinical dosage of gentamicin is difficult. The authors examined the relation between gentamicin dosages and inner ear function in guinea pigs. STUDY DESIGN: This study is a basic science project designed to examine cochlear and vestibular function in animal models. METHODS: Various concentrations of gentamicin solution were infused into the right inner ear of guinea pigs by osmotic pumps. Caloric nystagmus as a marker of vestibular function and the change in auditory brainstem response (ABR) threshold as a marker of cochlear function were observed. RESULTS: After 14 days of treatment, high gentamicin concentrations of 40 mg/mL caused canal paralysis and a rapid shift in ABR threshold. Animals exposed to low gentamicin concentrations of 4 mg/mL showed no obvious change in either vestibular or cochlear function. Animals exposed to moderate gentamicin concentrations of 12 mg/mL showed a moderate shift in ABR threshold and caloric malfunction. Histopathological examination revealed that after 14 days of treatment with 40 mg/mL gentamicin, severe cytoplasmic damage occurred in both vestibular and cochlear end organs. In animals treated with 12 mg/mL gentamicin, hair cells remained in the cochlear third turn and ampulla of the lateral semicircular canal. CONCLUSION: The authors established an animal model that showed the moderate damage of inner ear with moderate-dose gentamicin. The study results indicated that the appropriate administration of gentamicin could establish a stable effect on the inner ear. It may be important to select the protocol that delivers a stable dosage of gentamicin to treat patients with Meniere's disease safely and effectively.