Multi‐scale finite element modeling of Eustachian tube function: influence of mucosal adhesion

Abstract

The inability to open the collapsible Eustachian tube (ET) leads to the development of chronic Otitis Media (OM). Although mucosal inflammation during OM leads to increased mucin gene expression and elevated adhesion forces within the ET lumen, it is not known how changes in mucosal adhesion alter the biomechanical mechanisms of ET function. In this study, we developed a novel multi-scale finite element model of ET function in adults that utilizes adhesion spring elements to simulate changes in mucosal adhesion. Models were created for six adult subjects and dynamic patterns in muscle contraction were used to simulate the wave-like opening of the ET that occurs during swallowing. Results indicate that ET opening is highly sensitive to the level of mucosal adhesion and that exceeding a critical value of adhesion leads to rapid ET dysfunction. Parameter variation studies and sensitivity analysis indicate that increased mucosal adhesion alters the relative importance of several tissue biomechanical properties. For example, increases in mucosal adhesion reduced the sensitivity of ET function to tensor veli palatini muscle forces but did not alter the insensitivity of ET function to levator veli palatini muscle forces. Interestingly, although changes in cartilage stiffness did not significantly influence ET opening under low adhesion conditions, ET opening was highly sensitive to changes in cartilage stiffness under high adhesion conditions. Therefore, our multi-scale computational models indicate that changes in mucosal adhesion as would occur during inflammatory OM alter the biomechanical mechanisms of ET function.

Multi-scale modeling of an upper respiratory airway: Effect of mucosal adhesion on Eustachian tube function in young children

“…Although we previously quantified the amount of ET opening via the number of ruptured springs 18 , in young children the % spring rupture did not accurately represent ET function.…”

“…Similar hyperelastic constitutive models have been used to model both ET mechanics and other soft-biological tissues 5,18,22 . The PMT was modeled as a Maxwell viscoelastic material defined as.…”

“…Following our previous study 18 , mucosal adhesion was simulated by incorporating nonlinear, rupturable spring elements that connected nodes on the medial and lateral surfaces of lumen (see Figure 2A and orange elements in 2C). Springs were specified using a linear force-displacement relationship with spring constant K a and rupture distance x r .…”

“…In addition, infection of the ET-ME system results in the overexpression of muco-adhesive glycoproteins and the secretion of viscous mucus fluid into the lumen [14][15][16][17] which may further exacerbate ETD by increasing luminal adhesion forces. Previously, our laboratory incorporated mucosal adhesion dynamics into 3D finite element models of the adult ET 18 . Although those computational models indicate that increased mucosal adhesion can significantly alter the biomechanics of ET function in normal adults, they did not account for the pathologic anatomy found in young children and did not simulate airflow dynamics during ET opening.…”

Functional Aspects of the Eustachian Tube by Means of 3D-Modeling

“…In addition, optical coherence tomography might present new possibilities for three dimensional imaging . Also, three-dimensional modeling 28,29 and simulations such as finite element methods 7,30,31 have been applied. Furthermore, other endoluminal diagnostics 32,33 and therapies of the ET such as balloon dilatation [34][35][36] and stenting 37,38 A detailed three-dimensional microanatomy study was conducted in the present study to better understand these functional aspects.…”