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- Study of the stress of the tensor tympani muscle for different cases of the eardrum.Publication . Garbe, Carolina; Gentil, Fernanda; Parente, Marco; Martins, Pedro; Jorge, Renato NatalThe middle ear contains tree ossicles: malleus, incus and stapes. The movement of the ossiscles can be enhanced by two muscles, the muscle of the stapes (stapedius muscle) and the muscle of the malleus (tensor tympani).
- Numerical simulation of the maneuvers performed in vestibular rehabilitationPublication . Santos, Carla F.; Parente, Marco; Belinha, Jorge; Jorge, Renato Natal; Gentil, FernandaThe 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. Vestibular rehabilitation consists in a set of exercises, known as maneuvers, which can reduce and even eliminate the symptoms of dizziness and imbalance associated with a vestibular disorder. In this work, a three-dimensional model of the vestibular system, containing the fluids which promote the body balance, will be used. One of the aims is to simulate the fluid behaviour and the study of its interaction with the soft tissues of the vestibular structure. This model will allow the simulation of the maneuvers of the vestibular rehabilitation in order to improve its results and the quality of life of patients suffering from vertigo.
- The human otitis media with effusion: a numerical-based studyPublication . Areias, B.; Parente, M. P. L.; Santos, C.; Gentil, Fernanda; Natal Jorge, R. M.Otitis media is a group of inflammatory diseases of the middle ear. Acute otitis media and otitis media with effusion (OME) are its two main types of manifestation. Otitis media is common in children and can result in structural alterations in the middle ear which will lead to hearing losses. This work studies the effects of an OME on the sound transmission from the external auditory meatus to the inner ear. The finite element method was applied on the present biomechanical study. The numerical model used in this work was built based on the geometrical information obtained from The visible ear project. The present work explains the mechanisms by which the presence of fluid in the middle ear affects hearing by calculating the magnitude, phase and reduction of the normalized umbo velocity and also the magnitude and phase of the normalized stapes velocity. A sound pressure level of 90 dB SPL was applied at the tympanic membrane. The harmonic analysis was performed with the auditory frequency varying from 100 Hz to 10 kHz. A decrease in the response of the normalized umbo and stapes velocity as the tympanic cavity was filled with fluid was obtained. The decrease was more accentuated at the umbo.
- Estudo do efeito do atrito no contacto entre os ossículos do ouvido médicoPublication . Gentil, Fernanda; Jorge, Renato M. Natal; Ferreira, António J. Mendes; Parente, Marco P. Lages; Moreira, Miguel; Almeida, Eurico deO sistema auditivo comporta complexos fenómenos, entre eles o biomecânico. O ouvido médio é constituído pelos ossículos, martelo, bigorna e estribo, dos quais derivam ligamentos, músculos e tendões. A energia sonora é captada pelo pavilhão, canal auditivo externo e tímpano, sendo transformada em energia mecânica e transmitida aos ossículos. Neste trabalho efectuou-se a modelação do ouvido médio e respectivos ligamentos pelo Método dos Elementos Finitos, sendo a ligação entre ossículos efectuada por um modelo de contacto. A modelação dos ligamentos foi realizada pela utilização de uma formulação material baseada num modelo hiperelástico. Efectuaram-se estudos relativamente aos campos de deslocamentos, na membrana timpânica e na platina do estribo, assim como, as rotações verificadas na platina do estribo. Analisou-se ainda o campo de tensões induzidas nos ligamentos ao exterior da cadeia ossicular. Os estudos foram realizados para vários coeficientes de atrito entre os ossículos e para diferentes valores de pressão aplicados à membrana timpânica. A análise dos resultados obtidos permitiu concluir que a simulação da ligação entre os ossículos pode ser abordada com base numa formulação de contacto com atrito, podendo ser considerada como uma ligação quase rígida.
- 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.
- Finite element modelling of the surgical procedure for placement of a straight electrode array: Mechanical and clinical consequencesPublication . Areias, Bruno; Parente, Marco P. L.; Gentil, Fernanda; Jorge, Renato M. NatalA cochlear implant is an electronic device implanted into the cochlea to directly stimulate the auditory nerve. Such device is used in patients with severe-to-profound hearing loss. The cochlear implant surgery is safe, but involves some risks, such as infections, device malfunction or damage of the facial nerve and it can result on a poor hearing outcome, due to the destruction of any present residual hearing. Future improvements in cochlear implant surgery will necessarily involve the decrease of the intra-cochlear damage. Several implant related variables, such as materials, geometrical design, processor and surgical techniques can be optimized in order for the patients to partially recover their hearing capacities The straight electrode is a type of cochlear implant that many authors indicate as being the less traumatic. From the finite element analysis conducted in this work, the influence of the insertion speed, the friction coefficient between the cochlear wall and the electrode array, and several configurations of the cochlear implant tip were studied. The numerical simulations of the implantation showed the same pattern of the insertion force against insertion depth, thus indicating the different phases of the insertion. Results demonstrated that lower insertion speeds, friction coefficients and tip stiffness, led to a reduction on the contact pressures and insertion force. It is expected that these improved configurations will allow to preserve the residual hearing while reducing surgical complications.
- The biomechanical effects of stapes replacement by prostheses on the tympano-ossicular chainPublication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Santos, Carla; Almeida, Eurico; Jorge, Renato NatalHearing is a sequence of processes in which the ear translates sound waves into electrical signals, which are then sent to the brain where they are interpreted as sound. The ossicular chain of the middle ear is formed by three ossicles (malleus, incus, and stapes), of which the last and smallest, the stapes, vibrates, thus communicating with the inner ear through the stapes footplate. When abnormal bone formation immobilizes the stapes (otosclerosis), the passage of sound does not correctly occur and hearing can be compromised. In most cases, surgery is an option for its treatment. The stapes is totally or partially replaced by a prosthesis (stapedectomy or stapedotomy, respectively) allowing the passage of sound to the inner ear. This work presents a study on the behavior of different stapes prostheses, considering their biomechanical characteristics. The stapes was replaced by different prostheses, made of dissimilar materials: stainless steel, teflon, and titanium. The umbo and stapes footplate displacements for the models with these prostheses were obtained and compared with the displacements obtained with the model representative of the normal ear. In the models with prostheses, the displacements are found in the hole where the prosthesis is attached.
- 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.
- Desenvolvimento de um sistema de apoio a pacientes com zumbidoPublication . Ramos, Ana Rita Nunes; Ramos, Gina Maria Vilão; Costa, Maria Fernanda GentilO zumbido é um sintoma bastante perturbador, que se revela como uma sensação de “ouvir um som internamente”. Existem várias teorias que tentam justificar o seu aparecimento, embora nem sempre concordantes. Há estudos que relacionam o aparecimento de zumbido com a perda auditiva, exposição ao ruído, stress e perturbação emocional, mas ainda serão necessárias mais estratégias de tratamento para esta população específica. Ao avaliar pacientes com zumbido, percebe-se que as maiores queixas se relacionam com o silêncio da noite, o que, consequentemente, perturba o ciclo circadiano. De forma a colmatar este problema, foi construído um dispositivo inserido numa almofada, passível de ser utilizado durante o adormecimento. A almofada funciona como forma terapêutica, mais concretamente como gerador sonoro. Foi desenvolvido um dispositivo eletrónico que permite reproduzir varias faixas sonoras, e posteriormente inserido numa almofada. Além disso, foram testados alguns materiais para preencher o seu interior, e de todos os que se mostraram mais eficazes foram a esponja e os caroços de cereja. Os estudos foram no sentido de avaliar a melhor solução em termos acústicos, na propagação da onda sonora no meio ambiente, mas também a melhor solução em termos de maior conforto para o paciente. Foram obtidos resultados relativamente à propagação da onda sonora quando testada a almofada com esponja e com os caroços de cereja. Os melhores resultados relacionam-se com a almofada com os caroços de cereja, apresentando uma atenuação da intensidade de 24,1 dB relativamente ao som de referência, enquanto se obteve uma atenuação de 8,8 dB relativamente ao som no interior da almofada de esponja. A almofada criada é um dispositivo de fácil utilização, ecológico e que pode ser aplicado em todos os pacientes com queixas de zumbido noturno.
- 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.