前庭神经切断术后的前庭代偿观察

目的观察前庭神经切断术后的前庭代偿过程。方法对1998-2005年10例前庭神经切断术后患者．观察自发性眼震和平衡失调的持续时间，并对4例术前、后眼震电图进行对比观察。结果患者术后均出现快相向健侧的水平性眼震，持续4～7天消失，平衡失调恢复时间为一月至一年不等，年龄越大持续时间越长。4例进行眼震电图检查的患者，3例前庭功能均丧失，1例热水试验出现反向眼震。结论前庭代偿是前庭神经切断术后患者康复的必然过程，前庭康复训练可缩短前庭代偿的时间。     

迷路后径路前庭神经切断术治疗难治性梅尼埃病75例

目的 探讨迷路后径路前庭神经切断术治疗难治性梅尼埃病的手术安全性、可靠性、术后疗效。 方法 回顾性分析75例单侧难治性梅尼埃病患者行经迷路后径路前庭神经切断术的临床资料。 结果 75例患者平均病程(53.11±43.87)个月,术前500 Hz、1 000 Hz、2 000 Hz、4 000 Hz平均听阈(63.71±16.85)dB HL。听力分期Ⅱ期2例,Ⅲ期34例,Ⅳ期39例。Ⅱ期2例患者为内淋巴囊减压术后复发患者。术后颅内感染1例(1.3%)、脑脊液漏4例(5.3%)、暂时性面瘫1例(1.3%)、切口感染2例(2.6%)、切口脂肪液化3例(3.9%)。无颅内出血及术后即刻全聋的病例。术后眩晕疗效评定73例患者为A级,2例患者为B级。 结论 经迷路后前庭神经切断术疗效确切,风险与并发症可控,可显著改善患者生活质量。     

前庭代偿的发生机制

前庭代偿是一个中枢过程,其发生机制很复杂。本文从神经生理学、神经化学及神经药理学方面进行综述,供同道参考。     

梅尼埃病的选择性前庭神经切断术

选择性前庭神经切断术被广泛受为治疗顽固眩晕的标准的破坏性手术。本文对该手术入路的演变，手术步骤和效果分析等做了介绍。     

Ⅶ及Ⅷ脑神经复合束与前庭神经切断术的解剖研究

目的 探讨Ⅶ、Ⅷ脑神经复合束的应用解剖与前庭神经切断术径路的关系。方法 选用新鲜或神尔马林固定的带软组织尸耳34只，采取从上向下和暴露内耳道的方式进行解剖学研究。结果 （1）Ⅶ、Ⅷ脑神经复合束在由内耳道底向脑干行经过程中，存在着神经吻合、神经融合及神经旋转的独特现象；（2）耳蜗前庭裂亦存在3类变化。结论 保留听力的前庭神经切断术应尽量选择暴露内耳道的径路进行。     

c-fos癌基因表达及前庭代偿

在机体细胞中多种因素可诱导早期快反应基因(immediate early genes，IEGs)迅速一过性的表达，这种表达是机体对环境变化发生的一个重要过程。本介绍了早期快反应基因、前庭代偿(vestibular compensation)理论及早期快反应基因c-fs表达在前庭代偿机制研究中的应用，讨论了前庭中枢神经系统(central nerve system，CNS)在应答刺激过程中c—fos的表达特征，认为c—fos表达在前庭中枢神经系统间功能联系和定位的研究及前庭代偿机制形成的研究中有一定的应用价值。     

大鼠传出前庭神经元与传入前庭神经核的神经联系

目的阐明传出前庭神经元与传入前庭神经核的神经联系。方法将辣根过氧化物酶注射到大鼠面神经膝内侧传出前庭神经元区，经过48h的逆行轴突运输后用组织化学的方法在脑干中显示被标记的神经元。结果在双侧前庭神经内侧核及外侧核中均发现辣根过氧化物酶阳性标记细胞，以注射示踪剂同侧前庭神经内侧核数量最多。结论传出前庭神经元与前庭神经核间存在神经联系，本试验的结果提示前庭神经系统中可能存在前庭传入-传出反馈调节机制。     

Cannabinoid CB2 receptor expression in the rat brainstem cochlear and vestibular nuclei

Conclusion. This evidence suggests that both CB₁ and CB₂ receptors are important in the control of balance and hearing. Objective. Although the cannabinoid CB₁ receptor has been identified in the brainstem vestibular and cochlear nuclei, the existence of the second cannabinoid receptor subtype, the CB₂ receptor, has been more controversial. The aim of this study was to determine whether or not CB₂ receptors are expressed in the vestibular and cochlear nuclei. Materials and methods. Data were obtained from four young male Wistar rats In analyzing the presence of CB₂ receptors in the vestibular and cochlear nuclei, the immunohistochemical complex was visualized by exposure to diaminobenzidine for 20 min. Positive immunoreactivity to CB₂ was expressed as brown staining in the cytoplasm, nucleus, nuclear membrane and cell membrane. Results. We confirmed the existence of the CB₂ receptor in the vestibular and cochlear nuclei in the brainstem of Wistar rats.     

c-Fos expression in the mouse brainstem after unilateral labyrinthectomy

CONCLUSION: The results indicated that the vestibular, prepositus hypoglossal, and inferior olive nuclei were activated after unilateral labyrinthectomy in mice like in other species. It is expected that the application of the present procedure to appropriate gene-deficient mice will elucidate the mechanism of the process of vestibular compensation. OBJECTIVE: Vestibular compensation is attributed to functional and structural reorganization of neural networks in the central vestibular system, but its precise mechanism is still not clear. c-Fos protein is used as a marker of neuronal activation, because of its very limited expression in the normal state and rapid appearance after external stimulation. Previous reports, investigating c-Fos expression after unilateral labyrinthectomy were made in rats and guinea pigs, but not in the mouse brainstem. MATERIALS AND METHODS: For future application to the gene knockout mouse, we examined c-Fos expression in the mouse after unilateral labyrinthectomy. RESULTS: Twenty-four hours after surgery, significantly increased c-Fos positive cells were observed in the bilateral medial vestibular nucleus (MVe), bilateral spinal vestibular nucleus (SpVe), contralateral prepositus hypoglossal nucleus (PrH), and contralateral inferior olive nucleus (IO).     

CGRP expression in the vestibular periphery after transient blockage of bilateral vestibular input

This study aimed to establish an animal model of reversible bilateral vestibular disorders that is suitable for examining the mechanisms of vestibular plasticity, and to observe the changes in the plasticity of vestibular efferent systems. Tetrodotoxin (TTX) was infused continuously for 7 days into the bilateral perilymph of guinea pig cochlea. We assessed the vestibulo-ocular reflex (VOR) for evaluating the vestibular function. We also investigated the changes in calcitonin gene-related peptide (CGRP) immunoreactivity in vestibular end organs to observe the changes in the plasticity of vestibular systems. The VOR was completely eliminated by TTX administration and returned to the preoperative levels within 120 h after TTX discontinuation. An obvious increase in the number of CGRP-immunoreactive fibers was observed within the neurosensory epithelia of the maculae and cristae. An animal model of reversible bilateral vestibular disorders was established and used for investigating the plasticity of the vestibular nervous system.     

Inner ear lesion alters acoustically induced c-Fos expression in the rat auditory rhomboencephalic brainstem.

The pattern of c-Fos expression was mapped in the adult rat's brain following unilateral cochlear lesions. In normal and cochlear lesioned rats, c-Fos expression was induced with sound stimuli. Acoustic stimulation consisted of pulses of four tones. An additional control group consisted of non-stimulated rats. In the cochlear nuclei (CN), c-Fos activation was scarce in isolated rats and increased strongly following sound stimulation. Following unilateral cochlear lesion, acoustically driven expression was decreased in all CN in both the lesioned and the untreated sides. The ventromedial periolivary nucleus and the rostral periolivary nucleus showed c-Fos activation in isolated conditions and were strongly activated following sound stimulation. The rest of the superior olivary complex showed no c-Fos activation in isolated rats and a weak activation following sound stimulation. Following unilateral cochlear lesions, acoustically driven expression was decreased in some, but not all superior olivary nuclei in both the lesioned and the untreated sides. In the lateral lemniscus complex, c-Fos activation was scarce in isolated rats and increased strongly after stimulation. Following unilateral cochlear lesion, acoustically driven expression decreased bilaterally in all nuclei. We have found that unilateral inner ear lesions lead to bilateral impairment of the capability of acoustic pathway neurons, to being c-Fos-activated following sound stimulation.     

Changes in fos expression in the rat brainstem after bilateral labyrinthectomy

In order to elucidate the role of the vestibulocerebellar neural circuits during two-stage bilateral labyrinthectomy (BL) we examined Fos-like immunoreactive (-LIR) neurons as a marker of neural activation in the rat brainstem after BL and the projections of these neurons into the vestibulocerebellum using retrograde tracing and immunohistochemical techniques. Simultaneous BL did not show any Fos expression in the medial vestibular nucleus (MVe). However, with an interval of > 6 h between the two stages of BL, Fos-LIR neurons were induced in the ipsilateral (ipsi-) MVe of the side operated on second, partially projecting into the ipsi-vestibulocerebellum. A previous study demonstrated that some of the unilateral labyrinthectomy-induced Fos-LIR neurons in the ipsi-MVe projected into the ipsi-vestibulocerebellum and inhibited the contra-MVe neurons, resulting in the restoration of the right-left balance. Taken together with our present data, it is suggested that some of the labyrinthectomy-induced Fos expression in the ipsi-MVe is representative of a switch-on signal for the vestibulo-cerebello-vestibular inhibitory neural circuits, which remain turned off after symmetrical lesions such as simultaneous BL but are turned on after severe asymmetrical lesions in order to restore the balance.     

Recovery of postural control after an acute unilateral vestibular lesion in humans.

Postural control during stance was investigated using the EQUITEST system in 10 patients during recovery after an acute unilateral vestibular lesion and was compared to the time course of recovery of the static and dynamic vestibulo-ocular imbalance. During the acute phase the patients showed a characteristic pattern with normal upright stance as long as at least one accurate sensory input (visual or somatosensory) was provided and severe postural disturbances when they had to rely primarily on vestibular afferences. Both static vestibulo-ocular and vestibulo-spinal balance recovered very fast, showing basically normal results on postural testing within about 2 weeks after the lesion. Thereafter, no pathological pattern was detectable during postural testing even in patients with persistent complete unilateral vestibular lesions. Reflexive postural responses to unexpected rapid displacements of the support surface seemed not to be influenced by vestibular imbalance even in the acute phase of the lesion.     

Olivocochlear neurons in the brainstem of the mouse

The locations of efferent auditory neurons in the white mouse were determined using retrograde transport of HRP from the cochlea. Labeled neurons were localized in the lateral superior olivary nucleus (LSO) and ventral nucleus of the trapezoid body (VNTB). The total number of efferent neurons was determined to be 475; of these 34.5% are medial group efferents and 65.4% are lateral group efferents. The ipsilateral LSO contains 99% of the lateral group neurons and the contralateral VNTB contains 75% of the medial group neurons.