椎基底动脉供血障碍时耳蜗血流的变化及其调节

为了研究椎基底动脉供血障碍时耳蜗血流的变化及其调节作用，用激光多普勒血流计观察了３１只豚鼠椎基底动脉部分阻断时耳蜗血流及血压变化。其中５只豚鼠观察了罂粟碱及颈上神经节切除对内耳缺血的影响，发现惟基底动脉部分阻断时耳蜗血流明显减少（Ｐ＜０．００１），血压升高（Ｐ＜０．０５）。颈上神经节切除５分钟，耳蜗血流及血压无明显变化文Ｐ＞０．０５）。罂粟碱应用后２０分钟，耳蜗血流明显改善（Ｐ＜０．０００１）。颈上神经节切除后再次给予罂粟碱，耳蜗血流亦有增加，但较单纯应用罂粟碱时低。耳蜗血流与血压两者间无相关性。提示椎基底动脉供血障碍时耳蜗血流减少比较持续而稳定，罂粟碱明显改善豚鼠耳蜗血流说明肌源性调节的作用，而交感神经对内耳血流调节作用微弱。     

尼莫地平对正常和椎基底动脉供血障碍时耳蜗血流的影响

目的 :探讨尼莫地平对耳蜗血流的影响。方法 :用激光多普勒血流计对 2 2只正常及椎基底动脉供血障碍时豚鼠耳蜗血流测量。结果 :低浓度、临床常用浓度、高浓度的尼莫地平对内耳正常供血状态下或是椎基底动脉供血不足内耳缺血状态下的耳蜗血流均无增加作用。结论 :尼莫地平不能增加耳蜗血流反而降低耳蜗血流 ,在治疗内耳微循环障碍性疾患时应慎用。     

一氧化氮和心钠素对耳蜗血流的影响

内耳的血供主要来自基底动脉或小脑前下动脉分支的迷路动脉。迷路动脉分出前庭动脉和蜗总动脉，后者又分为蜗固有动脉及前庭蜗动脉。耳蜗的血流主要来自蜗固有动脉的供应。对耳蜗供血的研究表明，耳蜗存在强大的血流自主调节功能。保证耳蜗局部组织的供血，以保护耳蜗局部组织免受血压急剧变化的冲击，对维持耳蜗局部水电解质平衡有重要作用。蜗固有动脉在蜗轴移行为蜗轴螺旋动脉（spiral modiolar artery，SMA），属于动脉的终末支，对耳蜗血流的调节起主要作用。     

突发性聋伴眩晕与后循环供血不足研究进展

突发性聋是突然发生的、原因不明的感音神经性听力下降，部分患者伴有眩晕、耳鸣等不适症状。内耳的血供主要来自椎基底动脉、小脑前下动脉或小脑后下动脉分出的内听动脉，内听动脉为终末支动脉，后循环供血不足会引起耳蜗缺血，导致听功能和（或）平衡功能障碍，故内耳血供障碍学说作为突发性聋的发病原因之一受到重视。由于听觉前庭损伤可先于后循环缺血的症状或体征发生，因此听觉前庭损伤的早期诊断和适当处理可提供防止梗塞进展到后循环较大区域的窗口期。临床医师应考虑急性听觉前庭损伤可能预示即将发生后循环区域梗死的可能性，尤其是当患者在脑磁共振成像上有基底动脉闭塞性疾病时。     

前庭学

980825椎基底动脉供血障碍对前庭血流的影响/李学佩…//北京医科大学学报一1 997,29(5)一451~453 目的:探索椎基底动脉供血障碍对前庭微循环的影响规律。方法:用自行设计制作的椎基底动脉脑缺血动物模型,通过激光多普勒测定椎基底动脉阻断前后前庭血流变化。结果:阻断前前庭血流为(194.00士45.26)rnV,阻断后为(131.00士43.64)mV,阻断后降至平均基线的67.53%。结论:本文采用的动物模型反映了椎基底动脉伴有颈动脉狭窄、主干及其分支病变时病理生理特点及临床经过。椎基底动脉狭窄引起前庭血流减少,导致眩晕和平衡障碍。表1参7(秦斯)980826鼓…     

基底动脉与眩晕

通过磁共振血管图（ＭＲＡ）观察前庭小脑功能失调的血管基础，明确椎基底动脉（ＶＢＡ）系统部分动脉供血不足与眩晕、步态不稳、失协调和平衡障碍等功能失调的关系。被研究者年龄为６０～９０岁，以眩晕为主诉，但排除心源性疾病、直立性低血压、心理性因素及原发性耳性眩晕如梅尼埃病、前庭神经炎、听神经瘤和位置性眩晕。ＭＲＡ显示被研究者５０％出现血管形态学或动脉灌注不足的病变，如：椎动脉直接从主动脉弓发出、颈内动脉发出三叉动脉和舌下动脉、左椎动脉缺如伴左颈动脉栓塞、基底动脉狭窄、罕见的基底动脉长扩张（ｄｏｌｉｃｈｅ…     

神经生长因子家族及其受体基因表达与内耳组织发育…

本介绍了鼠胚胎内耳发育期及成年后耳蜗和前庭组织ＮＧＦ家族成员及其受体的表达规律，胚胎早期，听囊的耳蜗区域表达ＮＴ－３，前庭区域表达ＢＤＮＦ，胚胎中晚期，ＮＴ－３，ＢＤＮＦ在耳蜗、前庭区域均表达，成年后，ＮＴ－３是螺旋器的主要神经营养因子，ＢＤＮＦ是前庭的主要经营养因子。ＮＴ－３、ＢＤＮＦ与毛细胞的发育、分化相关。     

激光多普勒测量后半规管壶腹嵴血流

建立测定前庭血流的方法学是研究前庭微循环的关键。应用激光多普勒血流计测定１０只豚鼠的后半规管壶腹嵴血流。结果：耳蜗血流为３１８．３９±９１．６６ｍＶ，后半规管壶腹嵴血流为１９４．００±４５．２６ｍＶ，在测定过程中血压稳定在９．９９～１０．２７ｋＰａ。前庭和耳蜗血流分别占内耳血流的３７．８６％和６２．１４％，前庭血流约为耳蜗血流的二分之一。可以认为，后半规管壶腹嵴血流在一定程度上反映前庭血流变化。激光多普勒具有连续、动态、实时、直接观察、且能重复的优点。     

突发性聋与颈静脉球憩室关系初探

为探讨颈静脉憩室（ＪＢＤ）与突发性聋（突聋）的相关性，报告收治突聋１９例中，ＣＴ及磁共振血管造影显示右侧ＪＢＤ３例，共颈静脉孔和乙状窦均明显扩大。其产生内耳功能障碍的机理可能为：①ＪＢＤ压迫与阻塞耳蜗导水管和（或）前庭导水管，甚至内淋巴囊；②ＪＢＤ内的迂回血流对内耳的流体机械力学影响。提示：原因不明的内耳功能障碍病人，应作影像学检查，考虑有无ＪＢＤ的相关影响。     

豚鼠上橄榄外侧核γ—氨基丁酸阳性神经元向耳蜗和和耳…

为探讨豚鼠上橄榄外侧核内γ－氨基丁酸（ＧＡＢＡ）阳性神经元是否同时支配同侧Ｃｏｒｔｉ器和耳蜗核，采用逆行追踪的方法，将Ｆａｓｔ ｂｌｕｅ（ＦＢ）和Ｄｉａｍｉｄｉｎｅ黄（ＤＹ）两种不同性质的荧光素分别注入耳蜗鼓阶及同侧耳蜗核，观察上橄榄外侧核内ＧＡＢＡ阳性神经元的分支投身。结果发现，同侧上橄榄外侧内ＦＢ单标细胞占记细胞的８０．８％；ＤＹ单标细胞占１２．４％；ＦＢ－ＤＹ双细胞占６％；ＧＡＢＡ、ＦＢ、Ｄ     

补阳还五汤减方对豚鼠内耳微循环障碍的影响

目的观察补阳还五汤减方对血瘀豚鼠内耳血流及血液流变性的影响.方法用肾上腺素制备急性血瘀证动物模型,用激光多普勒血流计测量耳蜗和前庭血流(CBF,VBF),并检测血液流变学指标.结果中药组全血粘度、红细胞滤过指数(FI)、红细胞压积(HCT)、血浆纤维蛋白原含量、TXB2与6-Keto-PGF1、比值(T/K)较模型组降低(P＜0.01或P＜0.05),CBF和VBF较模型组增加(P＜0.01).结论补阳还五汤减方能够通过改善血流流变性,恢复TXA2-PGI2动态平衡等途径增加内耳血流,改善急性血瘀证动物模型的内耳微循环.     

Response of cochlear blood flow to prostaglandin E1 applied topically to the round window

CONCLUSIONS: The increase in cochlear blood flow (CBF) after administration of prostaglandin E1 (PGE1) to the round window depends on increased blood flow through the anterior inferior cerebellar artery (AICA). OBJECTIVES: To evaluate the response of CBF to PGE1 applied topically to the round window, and to investigate the origin of blood flow changes after this topical application. MATERIAL AND METHODS: The response of CBF to topically applied PGE1 was measured by placing the tip of a laser Doppler probe on the bony wall of the basal turn of the cochlea after the middle ear mucosa over the cochlea had been removed in guinea pigs and rats. In rats, the CBF response to PGE1 administration was investigated after occlusion of the AICA or stapedial artery. RESULTS: CBF increased following PGE1 administration in both guinea pigs and rats. In rats, CBF increased from 100% to 132%+/-10% (mean+/-SD) after the topical application of 0.5 microl of a 0.014% PGE1 solution. CBF decreased after occlusion of the AICA or stapedial artery but did not increase after PGE1 administration during occlusion of the AICA. The CBF response to PGE1 administration was similar before and after occlusion of the stapedial artery.     

Contribution of stapedial artery to blood flow in the cochlea and its surrounding bone

This study was performed to elucidate the contribution of the stapedial artery (SA)--which has been considered to be independent of the vertebrobasilar system--to blood flow in the ear by observing ear blood flow in Sprague-Dawley rats. A laser-Doppler (LD) probe was positioned on the bony wall of the cochlear basal turn after removal of the middle ear mucosa. The LD output was measured while either or both the SA and the anterior inferior cerebellar artery (AICA) were occluded. The LD output decreased to 70.6+/-2.5% (mean+/-S.D.) of the baseline value following SA occlusion, and to 58.0+/-7.8% following AICA occlusion in 12 animals. The rebound phenomenon of blood flow, which is a type of autoregulation, was only observed after releasing AICA occlusion. Simultaneous occlusion of the SA and AICA decreased the LD output to 27.0+/-5.5% of the baseline value. The role of the contribution of the SA and AICA to the LD output is discussed.     

An animal model for hearing disturbance due to inner ear ischemia: photochemically induced thrombotic occlusion of the rat anterior inferior cerebellar artery

Summary A photochemical reaction between intravenous rose bengal and xenon light was used to induce a selective thrombus in the rat anterior inferior cerebellar artery (RICA). Compound action potentials (CAPs) were recorded by electrocochleography and cochlear blood flow (CBF) was monitored by laser Doppler flow-metry. Photothrombotic occlusion of the AICA caused inner ear ischemia to various degrees with or without alterations of the CAP. With use of this model we investigated the critical range of the CBF for preserving cochlear function, represented by the CAPs induced with 8 kHz half-wave of sinusoid at 100 dB SPL. Results then showed that a CBF range between 26.7% and 42.9% of baseline was somewhat critical for maintenance of cochlear function in an acute phase of ischemia. Pretreatment with heparin significantly delayed thrombotic occlusion of the AICA in a dose-dependent manner. Further use of our model for inner ear ischemia may be useful for studying pathophysiology and pharmacological therapy of cochlear disturbances subsequent to circulatory disorders.     

Response of cochlear blood flow to prostaglandin E1 applied topically to the round window

Conclusions. The increase in cochlear blood flow (CBF) after administration of prostaglandin E₁ (PGE₁) to the round window depends on increased blood flow through the anterior inferior cerebellar artery (AICA). Objectives. To evaluate the response of CBF to PGE₁ applied topically to the round window, and to investigate the origin of blood flow changes after this topical application. Material and methods. The response of CBF to topically applied PGE₁ was measured by placing the tip of a laser Doppler probe on the bony wall of the basal turn of the cochlea after the middle ear mucosa over the cochlea had been removed in guinea pigs and rats. In rats, the CBF response to PGE₁ administration was investigated after occlusion of the AICA or stapedial artery. Results. CBF increased following PGE₁ administration in both guinea pigs and rats. In rats, CBF increased from 100% to 132%±10% (mean±SD) after the topical application of 0.5?µl of a 0.014% PGE₁ solution. CBF decreased after occlusion of the AICA or stapedial artery but did not increase after PGE₁ administration during occlusion of the AICA. The CBF response to PGE₁ administration was similar before and after occlusion of the stapedial artery.     

Cochlear blood flow during occlusion and reperfusion of the anterior inferior cerebellar artery – effect of topical application of dexamethasone to the round window

Conclusion. Topical application of dexamethasone may support autoregulation of cochlear blood flow (CBF), although it had no direct effect on CBF. Objectives. Although intratympanic steroid therapy for patients with inner ear disorders is common, the mechanism by which steroids exert their effect is unclear. We investigated the response of CBF to topical application of dexamethasone onto the round window. Materials and methods. Two concentrations of dexamethasone (3.3 mg/ml and 33 mg/ml dexamethasone in 0.5 µl saline) were applied to the round windows of rats, and CBF responses were measured using a laser Doppler flowmeter. The effects on CBF of a 2 h occlusion of the anterior inferior cerebellar artery (AICA) and subsequent release of the clamp with or without previous dexamethasone application were investigated. Results. No significant change in CBF was observed after topical application of dexamethasone, and it did not affect the decrease in CBF caused by AICA occlusion. However, recovery of CBF after release of the AICA clamp was better in animals treated with dexamethasone than in those that did not receive dexamethasone.     

豚鼠内耳磁微粒栓塞缺血模型初探

OBJECTIVE: To set up an inner ear ischemic model in guinea pig with ferromagnetic embolism. METHODS: A magnet was fitted in the external auditory canal and carbonyl iron filings (1%, 1 ml/kg) was injected into jugular, then the inner ear vessels were obstructed by ferromagnetic spheres. Cochlear blood flow (CBF) and number of red blood cells in the stria vessels were used to detect the model's ischemia of cochleae. The slice of temple bone and basal membrane stained by silver nitrate were used for inner ear's histopathological observations. RESULTS: The iron spheres were amassed in the one and two-day-later's model of inner ear vessels, which resulted in embolism. The number of red blood cells in the stria vessels decreased and then recovered to normal level after 4 days, but the CBF decreased to 50% +/- 10% of basic level immediately and recovered to 99% +/- 41% 4 days later. Scattered lesion of out hair cell cilium could be seen in cochleae in eight-day-later's model, and degenerations in different degree were found in vascular stria. CONCLUSION: The methods of inner ear ischemic model with ferromagnetic embolism could be practical and the decrease of CBF was reversible, so it may be an ideal model for studying some ischemic inner ear diseases and evaluating the effects of therapeutic drugs.     

Local effects of nitric oxide on vestibular blood flow in the Mongolian gerbil

There is a paucity of studies regarding the regulation of vestibular blood flow (VBF), despite the possibility that vascular alterations may contribute to specific vestibulopathies. The current experiments used the Mongolian gerbil as an animal model since it provides easy surgical access to the vestibular end-organs and has been previously used for physiologic studies involving inner ear function. VBF changes were measured in the posterior semicircular canal using laser Doppler flowmetry following round window membrane (RWM) application of the nitric oxide donor 1, 3-propanediamine-N-[4-1-(3-aminopropyl)-2-hydroxy-2-nitrosohydrazino] butyl (spermine NONOate; SPNO) as a vasodilator. The specificity of the responses induced was tested via pretreatment with an NO scavenger, 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazonline-1-oxyl-3 -oxide (carboxy-PTIO; cPTIO). cP-TIO, SPNO, vehicle (control) or cPTIO/SPNO were applied to the RWM, during which blood pressure and VBF were monitored for baseline, treatment, and recovery conditions. Results showed concentration-dependent increases in flow, probably resulting from NO's vasodilatory action on local vasculature. cPTIO pretreatment was found to attenuate SPNO-induced VBF increases. These findings support a role of NO in maintaining the vestibular microcirculation.     

Experimental basis for lidocaine therapy in cochlear disorders.

In order to further our basic understanding of the effects of lidocaine hydrochloride in the inner ear, cochlear potentials and blood flow (CBF) were assessed after intravenous (i.v.), anterior inferior cerebellar artery (AICA), and local round window (RW) lidocaine administrations in guinea pigs and rats. Lidocaine RW applications produced a dose dependent decrease in compound action potentials (CAP) and cochlear microphonics (CM). The sensitivity changes were more pronounced at high frequencies. These findings suggest that lidocaine has specific pharmacological action in the inner ear other than simple anesthesia of the auditory nerve. The basal turn endocochlear potentials (EP) were not altered by topical lidocaine, implicating altered organ of Corti function following local application of lidocaine. RW applications of lidocaine had no effect on CBF or systemic blood pressure (BP). I.v. infusions caused substantial reductions in BP. In the case of systemic infusions the percent changes in CBF were equal to and accountable by the BP changes. The microinfusions (50 mg/ml, 100 nl/min) through AICA produced a 30%, long lasting increase in CBF. However, neither systemic lidocaine nor AICA infusions had an effect on CAP or CM. These findings indicate that systemically given lidocaine may not cross the blood-cochlear barrier and that the cochlear electrophysiological effects due to lidocaine when given locally are partly mediated by direct influence on cochlear hair cell function; they also suggest that lidocaine-induced interference with active ion transport in the lateral wall or an influence on CBF are not contributing factors.