Browsing by Author "Parente, M. P. L."
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- A numerical study of fenestral otosclerosisPublication . Areias, B.; Parente, M. P. L.; Gentil, Fernanda; Natal Jorge, R. M.There are three basic types of hearing loss: conductive, sensorineural and mixed. Otosclerosis is a pathology which can originate any of these types of hearing loss. Otosclerosis is a bone dysplasia, present only in the temporal bone, and consists of single or multiple absorption areas followed by healing with bone neoformation. The clinical result of this pathology is a conductive deafness when a stapes footplate fixation occurs at the oval window or a sensorineural deafness when it affects the otic capsule involving the cochlear endosteum. Otosclerosis is categorised into two types, fenestral (stapedial type) and retrofenestral (cochlear type). Cochlear otosclerosis represents a continuation of the fenestral otosclerotic process and rarely occurs without fenestral involvement. The numerical model used in this work was build based on the geometrical information obtained from “The visible ear” project. A cryosectioning procedure was applied to the temporal bone of an 85 years old woman, without hearing pathologies, to obtain anatomical data. Afterwards, the different tissues were hand-segmented and a 3D model was constructed. The aim of this study is to contribute to the understanding of the alterations introduced by the fenestral otosclerosis in the human ear and its consequences on the earing capability, using a numerical analysis. The umbo and stapes displacements with the presence of fenestral otosclerosis were carried out for a stimulation of 80 dB SPL applied on the tympanic membrane. The stimulus was applied at frequencies ranging between 100 and 10 kHz. The main conclusion of this work is that the fenestral otosclerosis affects the motion of the stapes footplate, without changing significantly the umbo response.
- Stress analysis of the tympanic membrane through imagePublication . Garbe, Carolina; Parente, M. P. L.; Martins, Pedro Alexandre Lopes de Sousa; Jorge, Renato Natal; Gentil, Fernanda; Paço, JoãoTo 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.
- 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.