Browsing by Author "Areias, Bruno"
Now showing 1 - 10 of 17
Results Per Page
Sort Options
- 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.
- 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.
- 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.
- Effects of the fibers distribution in the human eardrum: A biomechanical studyPublication . Gentil, Fernanda; Parente, Marco; Martins, Pedro; Garbe, Carolina; Santos, Carla; Areias, Bruno; Branco, Carla; Paço, João; Jorge, Renato NatalThe 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.
- Facial nerve:a clinical and anatomical reviewPublication . Gentil, Fernanda; Campos, J.C. Reis; Parente, Marco; Santos, C.F.; Areias, Bruno; Jorge, R.M. NatalThe information that pass through the facial nerve allows the expression of our smile, joy or sadness, the “facial expression”. The face is the mark of our individuality. The facial nerve is responsible for innervation of the face muscles, like the previous two-thirds of the tongue and secretion of salivary and tears glands. The aim of this work is to remember the anatomy and physiology of the facial nerve, pathology and possible treatments of facial paralysis.
- A finite element model to predict the consequencesof endolymphatic hydrops in the basilar membranePublication . Areias, Bruno; Parente, Marco P. L.; Gentil, Fernanda; Caroça, Cristina; Paço, João; Jorge, Renato M. NatalMénière's disease is an inner ear disorder, associated with episodes of vertigo,fluctuant hearing loss, tinnitus, and aural fullness. Ménière's disease is associ-ated with endolymphatic hydrops. Clinical evidences show that this disease isoften incapacitating, negatively affecting the patients' everyday life. The patho-genesis of Ménière's disease is still not fully understood and remains unclear.Previous numerical studies available in the literature related with endolym-phatic hydrops, are very scarce. The present work applies the finite elementmethod to investigate the consequences of endolymphatic hydrops in the nor-mal hearing, associated with the Ménière's disease. The obtained results forthe steady state dynamics analysis are in accordance with clinical evidences.The results show that the basilar membrane is not affected in the same inten-sity along its length and that the lower frequencies are more affected by theendolymphatic hydrops. From a clinical point of view, this work shows therelationship between the increasing of the endolymphatic pressure andthe development of hearing loss.
- Finite element modelling of sound transmission from outer to inner earPublication . Areias, Bruno; Santos, Carla; Natal Jorge, Renato M; Gentil, Fernanda; Parente, Marco P. L.The ear is one of the most complex organs in the human body. Sound is a sequence of pressure waves, which propagates through a compressible media such as air. The pinna concentrates the sound waves into the external auditory meatus. In this canal, the sound is conducted to the tympanic membrane. The tympanic membrane transforms the pressure variations into mechanical displacements, which are then transmitted to the ossicles. The vibration of the stapes footplate creates pressure waves in the fluid inside the cochlea; these pressure waves stimulate the hair cells, generating electrical signals which are sent to the brain through the cochlear nerve, where they are decoded. In this work, a three-dimensional finite element model of the human ear is developed. The model incorporates the tympanic membrane, ossicular bones, part of temporal bone (external auditory meatus and tympanic cavity), middle ear ligaments and tendons, cochlear fluid, skin, ear cartilage, jaw and the air in external auditory meatus and tympanic cavity. Using the finite element method, the magnitude and the phase angle of the umbo and stapes footplate displacement are calculated. Two slightly different models are used: one model takes into consideration the presence of air in the external auditory meatus while the other does not. The middle ear sound transfer function is determined for a stimulus of 60 dB SPL, applied to the outer surface of the air in the external auditory meatus. The obtained results are compared with previously published data in the literature. This study highlights the importance of external auditory meatus in the sound transmission. The pressure gain is calculated for the external auditory meatus.
- 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.
- How the computational methods can contribute to better knowledge of the earPublication . Gentil, Fernanda; Parente, Marco; Santos, Carla; Areias, Bruno; Belinha, Jorge; Jorge, Renato NatalThe biomechanical behavior of the human ear can be studied using mathematical approaches, such as the finite element method. This methodology allows to perform simulations to evaluate the influence of sound transmission through all way of the ear, since the sound is selected by the outer ear to the inner ear. The finite element method is currently the preferred method for the numerical solution of partial differential equations, and it is used in several fields of the biological sciences. Due to its large applicability and efficiency, there are several works where this methodology is applied in different specialties, to analyze loads, strains or displacements, as in the case of the biomechanical study of the ear. From CT images, three-dimensional accurate computational models are created. The technique employs a set of calculations of numerical analysis for solutions of kinematic (displacements and rotations) and mechanical aspects (strength, stress, pressure, deformation). The use of these computer models enables the motion analysis of all ossicular chain points at any moment.