【作者】 沈双；

【导师】 刘迎曦； 孙秀珍；

【作者基本信息】 大连理工大学 ， 工程力学， 2013， 博士

【摘要】 人内耳前庭系统在维持身体平衡中起着先导作用。但是由于内耳埋藏位置深,结构复杂而精细,导致前庭常见疾病的病因和发病机制尚需明确,前庭功能检查定侧和定位上的诊断还缺乏有效手段,前庭疾病的治疗多限于对症。前庭系统功能异常和病理变化以及过度的外界环境激励是诱发眩晕的重要原因,严重影响了人们的生活质量。对于飞行员等特殊职业人员眩晕是导致飞行事故的重要因素。生物力学因素在内耳前庭系统行使平衡功能的过程中起着重要作用,其中前庭半规管感受头位有角运动依赖于管中内淋巴液的流动和嵴顶形变之问的相互作用和一个机电传导过程。将力学的基本原理与方法应用于人内耳前庭系统结构与平衡机制的相关性研究,可为探讨眩晕病症与内耳结构的相关性,提高前庭功能检查定侧、定位诊断敏感性,寻找有效治疗方法等提供定量依据。本文主要工作包括：1、通过对豚鼠内耳结构的研究,获得豚鼠内耳结构三维重建的有效方法。在此基础上,根据一例正常人内耳前庭半规管结构的数据,对其几何结构进行三维重建。采用有限元法对该半规管内淋巴液——嵴顶耦合系统进行了模态分析,得到系统的基频为13.46Hz,远高于人日常自然活动频率以及临床旋转试验和冷热试验的检查频率。2、进行了体位变化激励下人双耳前庭半规管平衡机制的数值分析。结果表明,头绕对称轴水平正弦转动或左右正弦滚转时,左右耳对称半规管的力学响应幅值相等,相位相差3.14rad,使得对称半规管的刺激强弱相反：头前后正弦翻转时,双耳对称半规管的力学响应幅值和相位均相等,使得对称半规管的刺激强弱相同。由此推断任意头位变化,通过前庭眼反射,双耳前庭半规管中的力学响应将诱发双眼向相同的方向等幅度转动,维持视网膜成像的稳定。3、对健康人双耳前庭半规管在人自然活动频率范围头水平转动进行了频率特性分析,寻找前庭半规管振动的特异性。研究发现水平半规管嵴顶椭圆囊侧表面的振动幅值对转动加速度较敏感,而管侧表面对转动速度较敏感,嵴顶振动的相位只与外载荷频率相关。随着外界载荷频率增大,水平半规管嵴顶两侧的振动幅值和相位差均增大。根据这一特异性,可以通过临床旋转试验定位评估水平半规管功能。4、进行了环境温度激励下人双耳前庭半规管平衡机制的数值分析。结果表明在外耳道口持续灌注冷热水或气,水平半规管被激励约20s后,前半规管才被稳定激励；约40s后,后半规管被稳定激励。推测临床Hallpike冷热试法对前后半规管功能的评估不可靠。为了通过冷热试法可靠地评定前后半规管的功能,需要延长在外耳道口灌注冷热水或气的时间,这个规律适用于任何头位冷热试验评定前庭半规管功能。5、探讨了椭圆囊内淋巴阀在人内耳前庭半规管平衡机制中的作用,对尚未明确的椭圆囊内淋巴阀的功能进行了探索。椭圆囊内淋巴阀张开后,任意头位变化,会使得内耳膜迷路上部和下部的内淋巴液体积不等量交换。如果体位变化激励越大,椭圆囊内淋巴阀的开口面积越大,通过开口交换的内淋巴液的体积将越多,对嵴顶变形运动的影响会越大,从而影响半规管的平衡机制。本文研究结果表明,椭圆囊内淋巴阀在前庭半规管行使平衡功能的过程中起着重要作用,如果其功能异常,可能增加梅尼埃病和良性阵发性位置性眩晕等前庭疾病的发生几率。更多还原

【Abstract】 The vestibular system in the inner ear plays a lead role in maintaining human balance function. However, the pathogenesis of common vestibular diseases has been fully unclear, the lateralization and localization diagnosis of lesion still lacks reliable clinical technology, and the treatment of vestibular disease is often based on the symptom. The reason is mainly due to the fact that the inner ear been deep buried in the temporal bone with fine complicated anatomy. It has been found that vestibular lesion and excessive environmental stimulation are the main factors leading to vestibular disorders with symptoms such as vertigo and dizziness, which seriously affect our daily life and cause aircraft accident. As we all know, biomechanics predominate in the process of maintaining equilibrium function of human vestibular system. It is reported that the ability of sensing angular movement for the vestibular semicircular canals mainly depends on the interaction between the endolymph flow and cupular deflection and mechano-electrical transduction processes. As a result, the basic theories and methods of mechanics have been developed to study the relativity between the anatomy of human inner ear vestibular system and its balance mechanism. In this study it will probe into the relationship between vestibular disorders and inner ear anatomy, promote lateralization and localization diagnoses of lesion, and provide quantitative basis for effective treatment of vestibular lesions. The main contents in this study are as follows:Firstly, we successfully obtained an effective method for reconstructing the three-dimensional geometry of guinea pig inner ear. Under this method, the inner ear geometry of a healthy human was reconstructed. The natural frequency and vibration mode for the endolymph-cupula system of this human inner ear was further obtained using finite element method. Based on our analysis, the first natural frequency is about13.46Hz, which is much higher than the maximum frequency of human daily activity and the examination frequency of clinical rotation test and caloric test.Secondly, we have numerically analyzed the balance mechanism of bilateral vestibular semicircular canals when a healthy human is subejected to postural changes. During head horizontal sinusoidal rotation or left-and-right rotation, the cupular vibration amplitude equals to each other between bilateral symmetrical semicircular canal with a phase difference of3.14rad, while both the cupular vibration amplitude and the phase are identical during head forth-and-back rotation. At the same time, corresponding afferent responses as well as the eye movement through vestibular ocular reflex will be induced. In this way, we are able to stabilize the visual image on the retina. Thirdly, in order to probe into the vibration characteristic of vestibular semicircular canals during head horizontal rotation, a frequency characteristic analysis for the right horizontal semicircular canal was made in the frequency range of human daily life. It was found that the vibration for the utricular side surface of the cupula is more sensitive to angular acceleration than head angular velocity, but that for the canal side surface is just opposite. Namely, the vibration of the canal side surface is more sensitive to angular velocity than angular acceleration. Furthermore, the difference of both vibration amplitude and phase across the two sides of the cupula will increase with the stimulus frequency. This phenomenon can be closely related to the localization diagnosis of horizontal semicircular canal lesion through clinical rotation test.Fourthly, the balance mechanism of bilateral vestibular semicircular canals was numerically analyzed when a healthy human is subejected to environmental temperature changes. Base on this analysis, anterior semicircular canal was found not considerably stimulated until20seconds after the horizontal semicircular canal did, while it was40seconds later when the posterior semicircular canal was considerably stimulated. It can be inferred that most clinical caloric tests, such as Hallpike test, were not suitable for effectively evaluating two vertical semicircular canals without enough irrigation, and it is applicable to any caloric test with different head position.Finally, a numerical model was developed in order to study the role of the utriculo-endolymphatic valve for the rotation-sensing capabilities of semicircular canals. Based on this model, we have found an unequal exchange of endolymph volume between the two parts of membranous labyrinth caused by head rotation. Both the bigger the stimulation and the larger the valve opening, the more endolymph volume would pass through. As a result, the larger effect would act on the cupular vibration as well as the balance mechanism. Naturally, the utriculo-endolymph valve plays an important role in modulating semicircular canals function. It will probably bring out Menier’s disease and benign paroxysmal positional vertigo with valve abnormality.更多还原