ABSTRACT
Current clinical practice is often unable to identify the causes of conductive hearing loss in the middle ear with sufficient certainty without exploratory surgery. Besides the large uncertainties due to interindividual variances, only partially understood cause-effect principles are a major reason for the hesitant use of objective methods such as wideband tympanometry in diagnosis, despite their high sensitivity to pathological changes. For a better understanding of objective metrics of the middle ear, this study presents a model that can be used to reproduce characteristic changes in metrics of the middle ear by altering local physical model parameters linked to the anatomical causes of a pathology. A finite-element model is, therefore, fitted with an adaptive parameter identification algorithm to results of a temporal bone study with stepwise and systematically prepared pathologies. The fitted model is able to reproduce well the measured quantities reflectance, impedance, umbo and stapes transfer function for normal ears and ears with otosclerosis, malleus fixation, and disarticulation. In addition to a good representation of the characteristic influences of the pathologies in the measured quantities, a clear assignment of identified model parameters and pathologies consistent with previous studies is achieved. The identification results highlight the importance of the local stiffness and damping values in the middle ear for correct mapping of pathological characteristics and address the challenges of limited measurement data and wide parameter ranges from the literature. The great sensitivity of the model with respect to pathologies indicates a high potential for application in model-based diagnosis.
Subject(s)
Acoustic Impedance Tests , Ear, Middle , Acoustic Impedance Tests/adverse effects , Acoustic Impedance Tests/methods , Algorithms , Ear, Middle/pathology , Hearing Loss, Conductive/diagnosis , Hearing Loss, Conductive/etiology , HumansABSTRACT
Introduction: The resonant frequency is the probe frequency in which susceptance is 0 due to the neutralization of the forces of mass and stiffness components that control the middle ear. This frequency can be evaluated by multifrequency tympanometry, and the normality value for adults ranges 800-1,200 Hz. Studies about resonant frequency in children are scarce. Aim: Identify the variation of the resonant frequency in infants between the first days after birth and the third month of life. Method: Prospective study. Thirty newborns were evaluated at 2 different times: at the neonatal phase up to 12 days of life, and between 72 and 84 days of life. In the first evaluation, we carried out otoacoustic emissions and identified the resonant frequency, and identified the resonant frequency again in the second evaluation. Results: In the first evaluation, we determined a mean resonance value of 250 Hz for both ears, while that in the second evaluation was 385 Hz. In both assessments, we found no significant differences between the ears. There was a significant difference between the first and second evaluation. Conclusion: The middle ear resonant frequency in infants is lower in the first days of life due to the influence of the mass component. The present study demonstrated that the resonance frequency increased in the first months of life...
Subject(s)
Humans , Male , Female , Infant, Newborn , Child , Adolescent , Ear, Middle , Hearing Tests , Otoacoustic Emissions, Spontaneous , Hearing Loss/prevention & control , Risk Factors , Acoustic Impedance Tests/adverse effectsABSTRACT
We studied 109 children with otitis media with effusion of 2 months' duration or longer that was unresponsive to medical management. Eighty-six subjects who had neither "significant" hearing loss nor defined symptoms were randomly assigned to receive myringotomy, myringotomy with tympanostomy tube insertion, or no surgery, and 23 subjects with significant hearing loss, defined symptoms, or both were randomly assigned to receive either myringotomy or myringotomy with tube insertion. Myringotomy with tube insertion provided more disease-free time and better hearing than either myringotomy alone or no surgery; however, some subjects who underwent myringotomy with tube insertion developed otorrhea or persistent perforation of the tympanic membrane. Myringotomy offered no advantage over no surgery regarding percent of time with middle-ear effusion, number of acute otitis media episodes, and number of subsequent surgical procedures. These results may not properly be extrapolated to less severely affected children.
Subject(s)
Middle Ear Ventilation , Otitis Media with Effusion/surgery , Tympanic Membrane/surgery , Acoustic Impedance Tests/adverse effects , Acoustic Impedance Tests/methods , Audiometry, Pure-Tone , Child , Child, Preschool , Chronic Disease , Ear Diseases/etiology , Follow-Up Studies , Hearing Loss/epidemiology , Humans , Infant , Middle Ear Ventilation/adverse effects , Otitis Media with Effusion/physiopathology , Random Allocation , RecurrenceABSTRACT
We report on two patients with sudden hearing loss occurring immediately after registration of an acoustically elicited acoustic reflex with pure tones of 500, 1000, 2000, and 4000 cps and 125 dB HL. Aetiology and patho-physiology of this form of acute acoustic trauma are discussed. An obvious destruction of middle ear structures or the membrane of the round and oval window can be excluded. Assuming pre-existing disposition, e.g. distortion of microcirculation in the cochlea, the acoustic stimulus is merely the trigger for the imminent sudden hearing loss. Therefore, we suggest to limit the stimulus power to 105 dB HL. In every case one should keep in mind the possible danger of this examination and perform a benefit-risk calculation in every patient.
