Three-dimensional finite element analysis of Eustachian tube function under normal and pathological conditions

Abstract

A primary etiological factor underlying chronic middle ear disease is an inability to open the collapsible Eustachian tube (ET). However, the structure-function relationships responsible for ET dysfunction in patient populations at risk for developing otitis media (OM) are not known. In this study, three-dimensional (3D) finite element (FE) modeling techniques were used to investigate how changes in biomechanical and anatomical properties influence opening phenomena in three populations: normal adults, young children and infants with cleft palate. Histological data was used to create anatomically accurate models and FE techniques were used to simulate tissue deformation and ET opening. Lumen dilation was quantified using a computational fluid dynamic (CFD) technique and a sensitivity analysis was performed to ascertain the relative importance of the different anatomical and tissue mechanical properties. Results for adults suggest that ET function is highly sensitive to tensor veli palatini muscle (TVPM) forces and to periluminal mucosal tissue (PMT) elasticity. Young children and cleft palate subjects exhibited reduced sensitivity to TVPM forces while changes in PMT stiffness continued to have a significant impact on ET function. These results suggest that reducing PMT stiffness might be an effective way to restore ET function in these populations. Varying TVPM force vector relationships via changes in hamulus location had no effect on ET opening in young children and cleft palate subjects but did alter force transmission to the ET lumen during conditions of elevated adhesion. These models have therefore provided important new insights into the biomechanical mechanisms responsible for ET dysfunction.

A Conceptual Study on Kaphaja Shiroroga with Special Reference to Sinusitis

“…The complications of chronic otitis media can affect both at intra-cranial level (meningitis, brain abscesses, thrombosis, extradural abscess, otologic hydrocephalus, encephalitis), as well as at extra-cranial level (facial nerve paralysis, mastoiditis, subperiosteal abscesses, labyrinthitis) [24]. In children, in particular, acute otitis media is recurrent due to greater horizontalisation with a smaller tube diameter, than in adults, and it becomes easier to reflux from the nasopharynx, or due to a different structure of the tube cartilage [3,9,10].…”

“…The intermittent opening of the pharyngeal ostium in the nasopharynx cause peristaltic-like movements, which are probably due to the visco-elastic nature of the tubular structure of the cartilage [3,8]. Yet, the opening of the ostium happens as a result of intervention strategies by the muscles, although we do not know the exact timing of the intervention and the precise actions of the muscles that interact with the tube.…”

“…This mechanism allows the ET to prevent the reflux of material and nasopharyngeal area pathogens into the middle ear, allowing for a smooth passage of air from the nasopharynx to the middle ear [2,3]. The tympanic membrane, in order to perform its function well, must vibrate properly when sound passes through it.…”

“…Yet, the opening of the ostium happens as a result of intervention strategies by the muscles, although we do not know the exact timing of the intervention and the precise actions of the muscles that interact with the tube. During swallowing or opening the mouth, the ostium of the nasopharyngeal tube opens, balancing the air pressure in the middle ear and clearing it [3,5,8,9].…”

“…The tensor muscle of the soft palate (TVP) dilates the ET lumen, but is also considered a masticatory muscle, as it is active during chewing, swallowing (acting on velopharyngeal movement) and phonation, orienting the tube inwards [2,3,10,11].…”