Comparison of otoacoustic emissions in patients with tinnitus having normal hearing versus mild hearing loss.

INTRODUCTION: Tinnitus 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. OBJECTIVE: This study investigates the cochlear function in patients with tinnitus, using Distortion Products Otoacoustic Emissions (DPOAE). MATERIAL AND METHODS: 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. RESULTS AND CONCLUSIONS: 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.

Numerical study of Hough technique in surgery of otosclerosis, using the finite element method.

PURPOSE: Otosclerosis is a metabolic bone disease of the otic capsule that can cause the stapes fixation, resulting in conductive hearing loss or, in a profound sensorineural deafness threshold. Surgery is one of the possible treatments for the otosclerosis. To repair small focus of otosclerosis in the anterior crus of the stapes, in 1960, Hough suggested the implementation of a technique in which part of the anterior crus is fractured and the stapes turned. As a result, the posterior crus of the stapes is the only connection with the inner ear. In this work, the outcome of Hough's surgical technique was simulated. METHODS: Based on computerized images, a finite element model of middle ear ossicles and tympanic membrane was created, as well as a model where the stapes has changed. The discretization of the tridimensional solid model was made using the ABAQUS software. The mechanical properties used were taken from the literature and adequate boundary conditions were applied. RESULTS: The results obtained with the Hough technique simulation were compared with a representative model of the normal ear, taking into account the displacements obtained on the central part of the stapes footplate and the maximum principal stress in the stapes crus. CONCLUSIONS: The results obtained are closer to the normal ear model, therefore Hough technique stands out as a good option to correct small focus of otosclerosis.

The biomechanical effects of stapes replacement by prostheses on the tympano-ossicular chain.

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.