Browsing by Author "Natal, Renato"
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- 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.
- Efeitos biomecânicos da evolução do colesteatoma sobre a corda do tímpanoPublication . Gentil, Fernanda; Mendonça, Leonor; Santos, Carla; Parente, Marco; Areias, Bruno; Natal, RenatoA otite média crónica pode levar ao aparecimento de um tumor benigno do ouvido, chamado colesteatoma. Esta patologia, se não for devidamente tratada, pode ter graves consequências. Uma delas pode resultar em paralisia facial se comprimir um ramo do nervo facial que atravessa o ouvido médio. Neste trabalho foram avaliadas as tensões exercidas do tumor contra o nervo. A maior tensão foi obtida na área de contacto entre o nervo e a bigorna.
- Influence of the insertion speed during a straight electrode array implantation, a numerical studyPublication . Areias, Bruno; Parente, Marco; Gentil, Fernanda; Natal, RenatoApproximately 466 million people worldwide suffer from some type of hearing loss. About ninety-three percent of them are adults, aged over 15 years (World Health Organization 2018). Profound hearing loss in children lead to a deficient development of spoken language, resulting in a negative impact on daily communication. On the other hand, in adults which have acquired the profound hearing loss after having developed spoken language and cognitive abilities are able to use these skills with the help of a cochlear implant, as mentioned by Jorgensen et al. (Jorgensen et al. 2018). Cochlear implant is an electronic device implanted into the cochlea to directly stimulate the auditory nerve. This device is particularly implanted in patients with severe-to-profound hearing loss (Khater and Mohammad 2017). The surgery is safe, but involves some risks, such as infections, device malfunction which can lead to poor hearing outcome (Loundon et al. 2010). Future improvements in cochlear implant surgery will necessarily involve the decrease of the intra-cochlear damage, thus preserving the patient’s residual hearing. The mechanical properties of the electrode array components, the geometrical shape, the processor and the surgical techniques are some of the aspects that can be optimized in order to help the patients to recover their normal hearing capacities. In this work, the influence of the insertion speed during a cochlear implantation was studied. A straight electrode array was initially modelled. Many authors indicate as being the less traumatic type of cochlear implant. The electrode array was meshed with linear hexahedral elements, with reduction integration, whereas the cochlear wall was modelled with 4-node shell elements. Four different insertion speeds: 0.25, 0.5, 1 and 2m/s were investigated. The numerical simulations of the cochlear implantation carried out in Abaqus software showed the same pattern of the insertion force against insertion depth, thus indicating the different phases of the implantation. Results demonstrated that lower insertion speeds, led to a reduction on the contact pressure and insertion force. It is then expected that a lower insertion speed will allow to increase the residual hearing while reducing surgical complications.
- A influência da ativação dos músculos do ouvido médio no seu comportamento biomecânicoPublication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Paço, João; Natal, RenatoA 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.