Repository logo

Browsing by Author "Garbe, Carolina"

Now showing 1 - 10 of 10
  • Análise dinâmica do comportamento mecânico do ouvido médio com prótese total
    Publication . Gentil, Fernanda; Marques, Marco; Garbe, Carolina; Santos, Carla; Parente, Marco; Martins, Pedro; Jorge, Renato
    O 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.
    2013-02Conference object Restricted access Show more
  • Analysis of eardrum pathologies using the finite element method
    Publication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Ferreira, António; Jorge, Renato Natal; Santos, Carla; Paço, João
    This 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.
    2014Journal article Open access Show more
  • Effects of the fibers distribution in the human eardrum: A biomechanical study
    Publication . Gentil, Fernanda; Parente, Marco; Martins, Pedro; Garbe, Carolina; Santos, Carla; Areias, Bruno; Branco, Carla; Paço, João; Jorge, Renato Natal
    The eardrum separates the external ear from the middle ear and it is responsible to convert the acoustical energy into mechanical energy. It is divided by pars tensa and pars flaccida. The aim of this work is to analyze the susceptibility of the four quadrants of the pars tensa under negative pressure, to different lamina propria fibers distribution. The development of associated ear pathology, in particular the formation of retraction pockets, is also evaluated. To analyze these effects, a computational biomechanical model of the tympano-ossicular chain was constructed using computerized tomography images and based on the finite element method. Three fibers distributions in the eardrum middle layer were compared: case 1 (eardrum with a circular band of fibers surrounding all quadrants equally), case 2 (eardrum with a circular band of fibers that decreases in thickness in posterior quadrants), case 3 (eardrum without circular fibers in the posterior/superior quadrant). A static analysis was performed by applying approximately 3000Pa in the eardrum. The pars tensa of the eardrum was divided in four quadrants and the displacement of a central point of each quadrant analyzed. The largest displacements of the eardrum were obtained for the eardrum without circular fibers in the posterior/superior quadrant.
    2016Journal article Open access Show more
  • A influência da ativação dos músculos do ouvido médio no seu comportamento biomecânico
    Publication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Paço, João; Natal, Renato
    A cadeia timpano-ossicular do ouvido médio humano é composta por três ossículos, ligamentos, músculos e tendões. Estes músculos (tensor do timpano e estapédico) têm uma ação protetora do ouvido interno, evitando que sons fortes o possam danificar. Neste trabalho é estudado o comportamento destes músculos, procurando a influência correta sobre a biomecânica do ouvido médio. Com base em imagens de tomografia computorizada (TC), foi criado um modelo da membrana timpânica e ossículos. A discretização deste modelo 3D foi feita através do programa ABAQUS. Usando o modelo de Hill, procedeu-se a simulação dos músculos e os resultados foram comparados considerando o seu comportamento passivo e ativo.
    2011-02Conference object Restricted access Show more
  • Myringosclerosis and Otosclerosis - their effects in the stapes footplate
    Publication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Tavares, João Manuel R. S.; Jorge, Renato N.
    The ear connects people to the outside world and contributes to sense of balance. However, a number of disorders can interrupt this perfect state, resulting in hearing impairment. Middle ear pathology, like myringosclerosis or otosclerosis is frequently seen and its early treatment is crucial to prevent others worst situations. The myringosclerosis is a formation of dense connective tissue in the eardrum, not usually associated with hearing loss. Otosclerosis is an abnormal growth of bone near the stapes and can result in conductive and/or sensorineural hearing loss.
    2012-07Conference object Open access Show more
  • Stapedotomy-hough technique to correct otosclerosis
    Publication . Gentil, Fernanda; Parente, Marco; Martins, Pedro; Garbe, Carolina; Almeida, Eurico; Tavares, João Manuel R. S.; Jorge, Renato Natal
    The stapes, the smallest bone in the human body, is the third component in the tympano-ossicular chain of the middle ear.
    2013Conference object Open access Show more
  • Stress analysis of the tympanic membrane through image
    Publication . Garbe, Carolina; Parente, M. P. L.; Martins, Pedro Alexandre Lopes de Sousa; Jorge, Renato Natal; Gentil, Fernanda; Paço, João
    To better understand the ear functioning, a biomechanical study of the tympanic ossicular chain of the middle ear was made. This chain consists of the tympanic membrane (which has 3 layers), three ossicles (malleus, incus and stapes), six ligaments, tendons and respective two muscles. The objective of this study was to analyze the stresses of the tympanic membrane through images, allowing a comparison of the different frequencies used. A geometric model of the tympanic membrane and ossicles was built through images of Computerized Axial Tomography (CAT). The discretization of this model was done using the finite element method, based on the ABAQUS software. The mechanical properties were obtained from previous work. The results were compared in the dynamic analysis of the tympanic ossicular chain for a frequency range between 100 Hz and 10 kHz, for a sound pressure level of 105 dB SPL, applied on the tympanic membrane. We can observe differences for each frequency in the tympanic membrane.
    2018Book part Restricted access Show more
  • 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 Natal
    The 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).
    2012Conference object Open access Show more
  • The biomechanical effects of stapes replacement by prostheses on the tympano-ossicular chain
    Publication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Santos, Carla; Almeida, Eurico; Jorge, Renato Natal
    Hearing 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.
    2014Journal article Unknown Show more
  • The influence of muscles activation on the dynamical behaviour of the tympano-ossicular system of the middle ear
    Publication . Gentil, Fernanda; Parente, Marco; Martins, Pedro; Garbe, Carolina; Paço, João; Ferreira, António J.M.; Tavares, João Manuel R.S.; Jorge, Renato Natal
    The human ear is a complex biomechanical system and is divided into three parts: outer, middle and inner ear. The middle ear is formed by ossicles (malleus, incus and stapes), ligaments, muscles and tendons, which transfers sound vibrations from the eardrum to the inner ear, linking with mastoid and Eustachian tube. In this work, a finite element modelling of the tympano-ossicular system of the middle ear was developed. A dynamic study based on a structural response to harmonic vibrations, for a sound pressure level (SPL) of 110, 120 and 130 dB SPL applied in the eardrum, is presented. The connection between the ossicles is made using a contact formulation. The model includes the different ligaments considering its hyperelastic behaviour. The activation of the muscles is based on the constitutive model proposed by previous work. The harmonic responses of displacement and pressure obtained on the stapes footplate, for a frequency range between 100 Hz and 10 kHz, are obtained simulating the muscle activation. The results are compared considering the passive and active states. The results are discussed and they are in accordance with audiological data published with reference to the effects of the middle ear muscles contraction.
    2013Journal article Unknown Show more