Reproducibility (test–retest) of vestibular evoked myogenic potential

IntroductionThere is still no consensus in the literature as to the best acoustic stimulus for capturing vestibular evoked myogenic potential (VEMP). Low-frequency tone bursts are generally more effective than high-frequency, but recent studies still use clicks. Reproducibility is an important analytical parameter to observe the reliability of responses.ObjectiveTo determine the reproducibility of p13 and n23 latency and amplitude of the VEMP for stimuli with different tone-burst frequencies, and to define the best test frequency.MethodsCross-sectional cohort study. VEMP was captured in 156 ears, on the sternocleidomastoid muscle, using 100 tone-burst stimuli at frequencies of 250, 500, 1000, and 2000 Hz, and sound intensity of 95 dB nHL. Responses were replicated, that is, recorded three times on each side.ResultsNo significant difference was observed for p13 and n23 latencies of the VEMP, captured at three moments with tone-burst stimuli at 250, 500, and 1000 Hz. Only the frequency of 2000 Hz showed a difference between captures of this potential (p < 0.001). p13 and n23 amplitude analysis was also similar in the test–retest for all frequencies analyzed.Conclusionp13 and n23 latencies and amplitudes of VEMP for tone-burst stimuli at frequencies of 250, 500, and 1000 Hz are reproducible.     

庆大霉素前庭损害报警耳聋的实验研究

目的观察庆大霉素对前庭及耳蜗的损害。方法对肌肉注射庆大霉素（250mg·kg－1／d）连续3天和7天的两组豚鼠进行前庭和耳蜗功能与形态的观察。结果发现用药3天仅影响前庭,而用药7天则前庭和耳蜗均受损害,提示庆大霉素早期损害前庭的特点可以报警耳蜗的损害。结论因此,在应用庆大霉素过程中,发现前庭功能改变时,如能及时停药,可以避免耳聋的发生。     

The effects of intense click sounds on velocity storage in optokinetic after-nystagmus

Vestibular evoked myogenic potentials (VEMP) occurring after click stimulation in cervical muscles are thought to be a polysynaptic response of otolith-vestibular nerve origin. In optokinetic after-nystagmus (OKAN) the direction of after-nystagmus changes and slow-phase velocity decreases with head tilt. This phenomenon may be an otolith response to the direction of gravity. We assumed that intense clicks might have some influence on OKAN via the otolith-vestibular nerve. Twelve normal subjects who showed VEMP at 75 dB normal hearing level (nHL) clicks were examined. The OKAN was recorded under four conditions: right monaural, left monaural and binaural stimulation by 75 dB nHL clicks, and absence of click stimulation. Horizontal optokinetic stimulation was applied using stepwise increasing speeds from 30 deg/s to 90 deg/s. Two seconds before the stimulus ended, clicks were sounded. The slow-phase velocity of the recorded electro-nystagmography was manually measured. There was no effect on OKAN with unilateral stimulation but binaural stimulation suppressed it. These results suggest that a velocity storage integrator is influenced by intense clicks via the otolithic area. Received: 17 November 1999 / Accepted: 30 May 2000     

听神经病伴发前庭下神经损害

目的 通过检测13例听神经病患者的前庭诱发的肌源性电位(vestibular evokedmyogenic potentials,VEMPs),了解听神经病患者是否同时伴发前庭下神经损害,探讨前庭下神经损害与听神经病的关系。方法 记录13例听神经病患者VEMPs,观察VEMPs表现形式;分析病程、低频听阈及言语识别率与VEMPs的关系。结果 13例听神经病患者中有7例存在VEMPs异常,占54％。异常的表现形式为VEMPs低振幅和VEMPs不能引出。正常VEMPs与异常VEMPs在低频听力损失、病程和言语识别率3个方面差异无显著性(P>0.05)。结论 部分听神经病患者伴发前庭下神经功能异常,说明两者病变可以同时并存;听神经病患者的病变程度方面与VEMPs无明显直接相关性,说明听神经病与前庭下神经损害两者之间又具有相对独立性。     

γ-氨基丁酸受体γ1亚基在大鼠前庭终器的表达

目的：研究γ-氨基丁酸受体γ1亚基在大鼠前庭终器的表达。方法；运用RT-PCR技术检测大鼠前庭终器编码GABAA受体亚基因表达。以大鼠脑组织RNA为阳性对照。结果：扩增出标志GABAA受体基因表达的PCR产物。结论:GABA受体γ1亚基在大鼠前庭终器有表达，为证明GABA是前庭系统重要神经递质之一提供了支持。     

Eye eccentricity modifies the perception of whole-body rotation

In order to explore the effect of gaze orientation on whole-body rotation perception, ten healthy participants were rotated in the dark while fixating on a visual target located either straight ahead or 15° to the right. A vestibular-memory contingent saccade paradigm was used to estimate the rotation perception. The results attest to the participants’ ability to accurately perceive their rotation, based solely on the intrinsic inputs (somesthetic and mainly vestibular), since the correlation between the imposed body rotation and the saccade amplitude was significant and positive. However, the rotation perception was less accurate and of lesser magnitude when the gaze was deviated in the opposite direction to the rotation than when it was either straight ahead or deviated in the direction of the rotation. This can be interpreted as the perceptual equivalent of Alexander’s law.     

梅尼埃病首发症状的临床分析

目的了解梅尼埃病患者的性别、首发的年龄、症状,并根据首发症状进行临床分类。方法回顾分析准确提供首发症状的145例梅尼埃病患者,按照耳聋和（或）耳鸣（耳蜗症状）、半规管（旋转性眩晕）和耳石器症状（倾到或平衡障碍）进行分类。结果首发症状依次为耳鸣45例、耳蜗加眩晕症状30例、眩晕28例、耳鸣加耳聋27例、听力下降9例、耳石器症状6例。累及耳蜗及前庭系统30例;累及耳蜗81例：累及半规管28例：累及耳石器6例。小于20岁和大于60岁年龄组患者数最少。男性高发年龄较女性高发年龄早10年,男性和女性在30-49岁年龄段发病例数最多。三种类型梅尼埃病临床首发症状与典型症状出现的间隔差异均较大。结论梅尼埃病耳蜗受累明显高于前庭,首发症状耳鸣最常见,其次是听力下降,再次为眩晕,倾倒的出现率最低。对不典型病例的早期诊断酌情选择纯音测听、耳蜗电图、前庭双温试验和前庭诱发的肌源性电位等检查。     

Vestibular hair cells isolated from guinea pig labyrinth

Living sensory cells were isolated from the cristae ampullaris and macula utriculi of the guinea pig. Enzymatic and mechanical dissociation were used to obtain different populations of hair cells, the most predominant being type I cells. Their form varied: cell body of variable roundness, and neck and cilia of different lengths. The observation of many tilted cuticular plates supports the hypothesis of active mechanisms regulating mechanotransduction at the apex of these cells. Cell viability was verified by double fluorescent labeling (FDA-PI), which indicated that under correct conditions about 90% of the sensory cells could be maintained in vitro for several hours after dissociation. The detection of actin in the cuticular plate and cilia shows that the technique has various potential applications in morphological studies, and can contribute to investigations on the physiology of mammalian vestibular cells.     

A morphometric study of the pallid mutant mouse inner ear

Mice homozygous for the mutant gene pallid (pa/pa) often lack otoconia in some or all of their maculae and are used to study the influences of gravity receptor hypostimulation on vestibular-related behaviors. Since the value of this animal model is based on the assumption that the vestibular sensorineural elements are normal, a morphometric analysis was done on the inner ear of these otoconia-deficient mice to see whether sensori-neural structures are also affected by the pallid gene. In pallid mice lacking all otoconia, the sensory epithelia of the utricle, saccule, and semicircular canal cristae were the same size as in their heterozygous (pa/+) controls. Although the superior and inferior divisions of the vestibular ganglion of the pallid mice were smaller than normal, the first-order neurons within these divisions were normal in size, number, and density. However, the superior divisions in both groups had larger neurons than did the inferior divisions. Within the pallid cochlea, first-order auditory neurons within the spiral ganglion were smaller than normal, but the scala media was larger. Since the significant vestibular influences of the pallid gene are limited primarily to the otoconia, behavioral abnormalities reported for these otoconia-deficient mice are apparently due only to gravity receptor hypostimulation.     

偏头痛性眩晕的神经耳科学表现

目的研究偏头痛相关的眩晕（migrainous vertigo，MV）的临床特点，了解听觉与前庭系统受累的情况以及功能障碍的范围和程度，判断偏头痛相关眩晕是中枢性抑或外周性眩晕。方法22例急性（5例）或亚急性（17例）MV检查包括神经一耳科学检查、自发性眼震和位置性眼震记录以及听力学检查。结果22例患者男6例，女16例。15例次有偏头痛，17例次有运动病，15例次有偏头痛或运动病家族史，1例次有视觉先兆，7例次对运动敏感（身体运动或改变头位出现眩晕），4例次畏光，6例次畏声，5例次失眠、情绪影响易引起眩晕发作，2例次与月经期关系密切。眩晕持续数分钟到1天。纯音测听异常9例，均为轻至中度感音神经性聋。高刺激率听性脑干反应双侧异常3例，单侧异常10例。主观垂直视觉检查均正常。前庭诱发的肌源性电位异常14例（13例为患侧低振幅，1例为患侧P13波潜伏期延长）。前庭双温检查异常3例；中枢性异常眼动11例，其中视动性眼震低增益9例，1例扫视过冲，1例摇头试验出现垂直眼震，同时高刺激听性脑干反应异常者10例，1例正常。4例患者有位置性眩晕，但均不符合良性阵发性位置性眩晕的诊断。结论偏头痛性眩晕应作为外周或中枢性眩晕的一种常规鉴别诊断的疾病，可为中枢性或外周性眩晕。