Ghadiali Samir N, Banks Julie, Swarts J Douglas
Department of Mechanical Engineering and Mechanics, Packard Laboratory, Lehigh University, Bethlehem, PA 18015, USA.
J Appl Physiol (1985). 2004 Aug;97(2):648-54. doi: 10.1152/japplphysiol.01250.2003. Epub 2004 Mar 26.
The inability to open the collapsible Eustachian tube (ET) has been related to the development of chronic otitis media. Although ET dysfunction may be due to anatomic and/or mechanical abnormalities, the precise mechanisms by which these structural properties alter ET opening phenomena have not been investigated. Previous investigations could only speculate on how these structural properties influence the tissue deformation processes responsible for ET opening. We have, therefore, developed a computational technique that can quantify these structure-function relationships. Cross-sectional histological images were obtained from eight normal adult human subjects, who had no history of middle ear disease. A midcartilaginous image from each subject was used to create two-dimensional finite element models of the soft tissue structures of the ET. ET opening phenomena were simulated by applying muscle forces on soft tissue surfaces in the appropriate direction and were quantified by calculating the resistance to flow (R(v)) in the opened lumen. A sensitivity analysis was conducted to determine the relative importance of muscle forces and soft-tissue elastic properties. Muscle contraction resulted in a medial-superior rotation of the medial lamina, stretching deformation in the Ostmann's fatty tissue, and lumen dilation. Variability in baseline R(v) values correlated with tissue size, whereas the functional relationship between R(v) and a given mechanical parameter was consistent in all subjects. ET opening was found to be highly sensitive to the applied muscle forces and relatively insensitive to cartilage elastic properties. These computational models have, therefore, identified how different tissue elements alter ET opening phenomena, which elements should be targeted for treatment, and the optimal mechanical properties of these tissue constructs.
咽鼓管（ET）无法打开与慢性中耳炎的发展有关。尽管ET功能障碍可能是由于解剖和/或机械异常引起的，但这些结构特性改变ET开放现象的确切机制尚未得到研究。以往的研究只能推测这些结构特性如何影响导致ET开放的组织变形过程。因此，我们开发了一种计算技术，可以量化这些结构 - 功能关系。从八名无中耳疾病史的正常成年人类受试者获取了横断面组织学图像。使用每个受试者的软骨中部图像创建ET软组织结构的二维有限元模型。通过在适当方向上对软组织表面施加肌肉力来模拟ET开放现象，并通过计算开放管腔中的流动阻力（R(v)）进行量化。进行了敏感性分析以确定肌肉力和软组织弹性特性的相对重要性。肌肉收缩导致内侧板向上内侧旋转，奥氏脂肪组织出现拉伸变形，以及管腔扩张。基线R(v)值的变异性与组织大小相关，而R(v)与给定机械参数之间的功能关系在所有受试者中是一致的。发现ET开放对施加的肌肉力高度敏感，而对软骨弹性特性相对不敏感。因此，这些计算模型确定了不同组织成分如何改变ET开放现象、哪些成分应作为治疗靶点以及这些组织结构的最佳机械特性。
