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Using meshless methods to simulate the free vibrations of the cupula under pathological conditions
Published in J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares, Biodental Engineering V, 2019
C.F. Santos, Marco Parente, J. Belinha, R.M. Natal Jorge, Fernanda Gentil
Saccule and utricle are the structures of the vestibular system, placed near the SCC, sensitive to the linear accelerations. Both structures are constituted by a macula layer where some calcium carbonate particles, which have an important role in the balance function are placed. This particles, known as otoconia, could detach from the macula and get lost in the SCC, which could lead to vertigo symptoms. Cupulolithiasis, represented in Figure 1c), is a vestibular condition when the otoconia get attached to the cupula inducing a false sensation of movement, leading to dizziness episodes. There are some rehabilitation manoeuvres that can be performed to solve the described problem. However, such manoeuvres do not always work. The symptoms of vertigo are severe and incapacitating, reducing the quality of life of patients.
Spatial Orientation and Disorientation
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
The loss of inhibitions and the impairment of cognitive function are well-recognized central effects of alcohol. Giddiness and unsteadiness of gait are also typical of excessive alcohol consumption. While this effect on balance may have a central component, the effect on the labyrinth is thought to arise as a consequence of a density disparity within the semicircular canal system. To function correctly as a rotation sensor, it is essential that the cupula within the ampulla of each semicircular canal remains insensitive to gravity. This is achieved by the cupula having exactly the same density as the endolymphatic fluid that surrounds it. Provided this is so, whatever the position of the head, the cupula tends neither to float nor to sink. Were it to do either, it would send a spurious signal to the brain to indicate rotation. It appears that alcohol in the circulation diffuses into the cupula before it reaches the endolymphatic fluid, and because alcohol is less dense than water sets up a density difference between the cupula and the endolymph. As a result, when a head movement brings the cupula into a more horizontal position, the subject becomes aware of a sense of vertigo.
Spatial Orientation
Published in Pamela S. Tsang, Michael A. Vidulich, Principles and Practice of Aviation Psychology, 2002
The labyrinth contains three narrow semicircular canals filled with the sodium-rich endolymph. The canals lie in planes that are mutually orthogonal to within 5 to 10° and respond to angular accelerations containing a component perpendicular to their plane. One end of each of the canals, near the entrance to the utricular sac, is widened to form the ampulla, which is normally completely blocked by a gelatinous wedge, the cupula. The cupula bends slightly, but prevents endolymph from flowing through the ampullary space. The base of the cupula widens into the crista, which contains cilia projecting from hair cells in the underlying neuroepithelium. Bending the hairs in the direction of the kinocilium increases the cell depolarization and increases the frequency of hair cell firing. In this manner, pressure changes in the endolymph, causing the cupula to deflect slightly, are transformed into changes in the firing rate of afferent nerve fibers traveling from the semicircular canals toward the brain.
A comprehensive finite element model for studying Cochlear-Vestibular interaction
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Junfeng Liang, Zhang Ke, Paige V. Welch, Rong Z. Gan, Chenkai Dai
Finite element (FE) simulation is a powerful tool for understanding the mechanics behind this interaction in the inner ear. Numerous FE models have been used to investigate the hydrodynamics in the cochlea either with passive (Zhang and Gan 2011; Edom et al. 2013; De Paolis et al. 2017) or active wave (Elliott and Ni 2018). Meanwhile, the vestibular system is also studied with FE simulation either focus on the hydro-dynamics of the endonym (Shen et al. 2013; Karimi et al. 2017; Santos et al. 2017; Iversen et al. 2018), pressure on cupula (Selva et al. 2010; Zdravkovic et al. 2017; Baumgartner et al. 2018; Yu et al. 2018) or the sensorineural response of cupula (Hayden et al. 2011; Schier et al. 2018; Hedjoudje et al. 2019). Albeit a myriad of simulation studies on cochlear or SCC exists, to date, very few inner FE models include both parts of the inner ear.
Smart platform for the analysis of cupula deformation caused by otoconia presence within SCCs
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Radun Vulović, Milica Nikolić, Nenad Filipović
In this paper, we gave a comparison of the numerical, analytical and FE results for the deformation of cupula during rotation of 120°. We showed that the problem can be solved analytically and that such solution almost perfectly fits with numerical solution. We also proposed the finite element solution of the problem and explained why and in what part it did not fit with the numerical and analytical solutions. Besides, we developed a mobile application for investigating how cupula deforms during head rotation while the endolymph in semicircular canals is being disturbed by the otoconia presence. The aim was to give clinical doctors an opportunity to conduct calculations, in a quick and easy manner, related to cupula deformation during head rotation and then analyse the results in an interactivity manner, i.e. observe solutions during rotating the smart phone about vertical axis, preferably mounted on a head strap with phone holder. It can be said that the most prominent features of this “mobile client - server” approach are the accessibility and efficiency in terms of mobile device usage, and power and scalability in terms of server engagement.