Browsing by Author "Parente, Marco"
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- An alternative 3D numerical method to study the biomechanical behaviour of the human inner ear semicircular canalPublication . Santos, Carla F; Belinha, Jorge; Gentil, Fernanda; Parente, Marco; Jorge, Renato NThe vestibular system is the part of the inner ear responsible for balance. Vertigo and dizziness are generally caused by vestibular disorders and are very common symptoms in people over 60 years old. One of the most efficient treatments at the moment is vestibular rehabilitation, permitting to improve the symptoms. However, this rehabilitation therapy is a highly empirical process, which needs to be enhanced and better understood.
- Análise dinâmica do comportamento mecânico do ouvido médio com prótese totalPublication . Gentil, Fernanda; Marques, Marco; Garbe, Carolina; Santos, Carla; Parente, Marco; Martins, Pedro; Jorge, RenatoO presente trabalho tem como objetivo analisar e caracterizar o comportamento do ouvido médio quando uma prótese total substitui os elementos da cadeia ossicular de forma a solucionar problemas de surdez de transmissão. com base num modelo geométrico da cadeia ossicular saudável, a partir de imagens de TAC, foi criado um modelo onde uma prótese total foi incluída, assim como todos os objetos inerentes a esta adição. Foi assim efetuado o estudo dinâmico de vibrações forçadas para um modelo utilizando o método de elementos finitos. Foram obtidos os deslocamentos ao nível do umbo e da platina do estribo, para diferentes níveis de pressão sonora aplicada sobre a membrana timpânica, quando presente uma cartilagem na interface membrana-prótese de diferentes diâmetros e espessuras. Os resultados obtidos foram comparados com o modelo da cadeia tímpano-ossicular normal. A utilização deste modelo tem como objetivo conseguir definir a técnica que promove, da melhor maneira possível, a performance de uma prótese total no ouvido médio. Com este estudo pode-se afirmar que a reabilitação do ouvido médio com próstese do tipo TORP apresentará melhores resultados quando são utilizadas cartilagens de 4mm de diâmetro, com espessuras entre os 0.3mm e os 0.4mm.
- Analysis of eardrum pathologies using the finite element methodPublication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Ferreira, António; Jorge, Renato Natal; Santos, Carla; Paço, JoãoThis work investigates the effect of eardrum perforations and myringosclerosis in the mechanical behavior of the tympano-ossicular chain. A 3D model for the tympano-ossicular chain was created and different numerical simulations were made, using the finite element method. For the eardrum perforations, three different calibers of perforated eardrums were simulated. For the micro perforation (0.6 mm of diameter) no differences were observed between the perforated and normal eardrum. For the numerical simulation of the eardrum with the largest perforation caliber, small displacements were obtained in the stapes footplate, when compared with the model representative of normal ossicular-chain, at low frequencies, which is related with major hearing loss in this frequency range. For the numerical simulations of myringosclerosis, the larger differences in the displacement field between the normal and modified model were obtained in the umbo. When observing the results in the stapes footplate, there were no significant differences between the two models, which is in accordance to the clinical data. When simulating an eardrum perforation along with myringosclerosis, there is a decrease in the displacements, both from the umbo and the central part of the stapes footplate, often associated with a pronounced hearing loss. It could be concluded that the reduced displacement of the stapes footplate may be related to a greater hearing loss.
- Biomechanical study of the vestibular system of the inner ear using a numerical methodPublication . Santos, Carla F.; Belinha, Jorge; Gentil, Fernanda; Parente, Marco; Areias, Bruno; Jorge, Renato NatalThe inner ear has two main parts, the cochlea, dedicated to hearing, and the vestibular system, dedicated to balance. Dizziness and vertigo are the main symptoms related to vestibular disorders, which commonly affects older people. In order to eliminate these symptoms a vestibular rehabilitation is performed; this consists in a range of movements of the head, known as maneuvers, performed by a clinical professional. This procedure does not always work as expected. The aim of this work is to contribute to a better understanding on how the vestibular system works. This knowledge will help in the development of new techniques that will facilitate a more efficient rehabilitation. In order to achieve that goal, a three-dimensional numerical model of the vestibular system, containing the fluids which promote the body balance, was constructed. The vestibular components will be discretized using the finite element method and the fluid flow will be analyzed using the Smoothed Particle Hydrodynamics The results obtained with the numerical model of the semicircular canal built to study the rehabilitation process are presented and compared with other authors. The solution achieved is similar with literature.
- Biomechanics of the vestibular system: a numerical simulationPublication . Santos, Carla F.; Belinha, Jorge; Gentil, Fernanda; Parente, Marco; Jorge, Renato M. NatalThe vestibular system is located in the posterior portion of the inner ear. It is a key component to our sense of balance and movement. Any changes in this system can cause effects or symptoms such as dizziness, blurred vision, imbalance, and nausea, which are vertiginous syndrome indicators. Vertigo is reported as one of the most common symptoms in the world. It is considered the third most frequent complaint in medicine, transmitting a sense of inadequacy and insecurity. The aim of this work is to contribute to a better understanding of how the vestibular system works. This knowledge will help in the development of new techniques that will facilitate a more effective rehabilitation. Vestibular rehabilitation consists of a set of exercises, known as maneuvers, which can reduce and even eliminate symptoms of dizziness and imbalance associated with a vestibular disorder. In this work, a three-dimensional computational model of the vestibular system, containing the fluids promoting the body balance, will be presented. The smoothed-particle hydrodynamics (SPH) method will be used to simulate the fluid behavior. The results provide a better comprehension of the biomechanics of the vestibular system, which contribute to recover from any system disorders.
- Comparison of otoacoustic emissions in patients with tinnitus having normal hearing versus mild hearing lossPublication . Gentil, Fernanda; Meireles, Susana; Roza, Thuane; Santos, Carla; Parente, Marco; Almeida, Eurico; Natal, RenatoTinnitus is an auditory sensation whose source comes from external stimulus to the body. All studies that can help people with this disorder are very imperative. This study investigates the cochlear function in patients with tinnitus, using Distortion Products Otoacoustic Emissions (DPOAE). Ears where the subjects referred to feel the tinnitus were considered for the study group while other ears without this sensation of tinnitus acted as a control group. Fifty subjects suffering from unilateral or bilateral tinnitus with normal hearing sensitivity or mild hearing loss were recruited. Where comparing the control and study group, the highest percentage of cases of DPOAE detected was in the control group, although these differences were not statistically significant. When the analyzed frequency is the same as the tinnitus frequency, the prevalence of detected DPOAE is in tinnitus ears (50.0 %). In ears where tinnitus was not perceived (73.5 %) a p value of 0.024 (< 0.05) was found, which means that the undetected DPOAE could be influenced by tinnitus. Based on the results, tinnitus might not be caused by changes in the outer hair cells but seems to be affected by that.
- A computational framework to simulate the endolymph flow due to vestibular rehabilitation maneuvers assessed from accelerometer dataPublication . Santos, Carla F.; Belinha, Jorge; Gentil, Fernanda; Parente, Marco; Areias, Bruno; Jorge, Renato NatalVertiginous symptoms are one of the most common symptoms in the world, therefore investing in new ways and therapies to avoid the sense of insecurity during the vertigo episodes is of great interest. The classical maneuvers used during vestibular rehabilitation consist in moving the head in specific ways, but it is not fully understood why those steps solve the problem. To better understand this mechanism, a three-dimensional computational model of the semicircular ducts of the inner ear was built using the finite element method, with the simulation of the fluid flow being obtained using particle methods. To simulate the exact movements performed during rehabilitation, data from an accelerometer were used as input for the boundary conditions in the model. It is shown that the developed model responds to the input data as expected, and the results successfully show the fluid flow of the endolymph behaving coherently as a function of accelerometer data. Numerical results at specific time steps are compared with the corresponding head movement, and both particle velocity and position follow the pattern that would be expected, confirming that the model is working as expected. The vestibular model built is an important starting point to simulate the classical maneuvers of the vestibular rehabilitation allowing to understand what happens in the endolymph during the rehabilitation process, which ultimately may be used to improve the maneuvers and the quality of life of patients suffering from vertigo.
- Computational simulation of the cupula behavior in vestibular pathologies of the inner earPublication . Santos, Carla; Gentil, Fernanda; Parente, Marco; Areias, Bruno; Belinha, Jorge; Natal Jorge, RenatoVertigo is reported as one of the most common symptoms in the world, commonly related with vestibular disorders. It is considered the third most frequent complaint in medicine, transmitting a sense of inadequacy and insecurity, mainly in elders. The aim of this work is to contribute to a better understanding on how the vestibular system works, mainly during vestibular rehabilitation process. This knowledge will help in the development of new techniques that will facilitate a more efficient rehabilitation. Vestibular rehabilitation consists in a set of exercises, known as maneuvers, that can reduce and even eliminate the symptoms of dizziness and imbalance associated with a vestibular disorder.
- Computational simulation of the vestibular system using a meshless particle methodPublication . Santos, C.F.; Parente, Marco; Belinha, J.; Natal Jorge, R.M.; Gentil, FernandaVestibular rehabilitation is the most used therapy in cases of unbalance diagnosis. The vertigo symptoms are commonly related with inner ear diseases, affecting 20%-30% of the world population (von Brevern & Neuhauser, 2011). Its prevalence is higher in elders. In this work, a three-dimensional model of the semi-circular canal of the vestibular system, containing the fluids that pro-mote body balance, will be used. The Smoothed-Particle Hydrodynamics (SPH) method, a meshless particle method, will be the discrete numerical technique used to simulate the fluid behaviour. In the SPH the discretization is represented by particles with constant mass (G.R. Liu & Liu, 2003). The obtained results allow to understand the behaviour of the vestibular structures during the rehabilitation manoeuvres.
- Cupula response to otoconia debris in the semicircular canalPublication . Santos, Carla F.; Belinha, J.; Gentil, Fernanda; Parente, Marco; Jorge, Renato NatalThe vertigo symptoms are commonly related with inner ear diseases and it affects 20%-30% of the world population, and its prevalence increases with age. In this work, a three-dimensional computational model of the semicircular canal of the vestibular system, containing the fluids which promote the body balance, was used. The smoothed-particle hydrodynamics method was the computational process used to simulate the fluid behaviour, in which the elements are represented by particles and have constant mass. The other vestibular components were discretized using the finite element method. The movement performed to endolymph/cupula interaction analysis was reproduced in the simulation through the acquisition of the displacement field based on image analysis. The results obtained with the frames of the video recorded during the process is the appropriate method to simulate the real moves, due to the analysis of the region of interest located near the inner ear. The data obtained from the video acquisition were the input in the simulation with the semicircular model. The principal stress cupular response allowed to understand the interaction of the vestibular structures during a vertigo episode, and the influence of the otoconia in the cupula displacement. This model is the first step to improve the vestibular rehabilitation and the quality of life of patients suffering from vertigo.