RESUMO
In order to study the effect of middle ear malformations on energy absorbance, we constructed a mechanical model that can simulate the energy absorbance of the human ear based on our previous human ear finite element model. The validation of this model was confirmed by two sets of experimental data. Based on this model, three common types of middle ear malformations,
Assuntos
Humanos , Ossículos da Orelha , Bigorna , MarteloRESUMO
OBJECTIVES: One of the risks in middle ear surgery is high frequency hearing loss. It is believed that manipulations on the middle ear ossicles with the instruments may cause overstimulation of the inner ear and damage of the hear cells. Controversy arises whether temporary separation of the ossicles has any impact on middle ear transfer function and hearing threshold after surgery. The aim of the study is to evaluate the influence of incudostapedial joint (ISJ) separation on middle ear function in an experimental model. METHODS: With the use of single point laser Doppler vibrometer (LDV) stapes velocity in the intact chain and after ISJ separation was measured in 5 fresh human cadaver temporal bones. RESULTS: In all cases there was a decrease in stapes velocity after ISJ separation. Mead stapes velocity was reduced for 1 dB in 800 Hz to 9 dB in frequencies above 1,000 Hz. The decrease of velocity was greater in higher frequencies. CONCLUSION: Separation of the ISJ does not reduce significantly the middle ear function.
Assuntos
Humanos , Cadáver , Orelha Interna , Orelha Média , Audição , Perda Auditiva , Articulações , Fluxometria por Laser-Doppler , Modelos Teóricos , Estribo , Osso TemporalRESUMO
The mechanism for conducting acoustic energy via middle ear oscicles is still a controversial topic and will remain so until consensus is reached regarding whether it amplifies or reduces sound transmission. 22 paired human temporal bone blocks and 1 left block were studied. Digital measurements were taken of the tympanic membrane, oscicular articulations and the oval window; the results were then correlated. A relationship of non-lineal areas was found amongst the structures being studied, suggesting a sound transmission relationship combining both sound reduction and amplification. A complex relationship of levers could be observed originating in an oscicular and articular asymmetric relationship suggesting an amplifying function in initial sound transmission and also a final reducer destination for such conduction.
El mecanismo para conducir la energía acústica a través de oscículos del oído medio es todavía un tema controvertido y lo seguirá siendo hasta alcanzar un consenso con respecto a si se amplía o reduce la transmisión del sonido. Fueron estudiados 22 pares de bloques de hueso temporal izquierdo y uno derecho hmanos. Mediciones digitales fueron tomadas de la membrana timpánica, articulaciones osciculares y de la ventana oval, siendo estos resultados correlacionados. Una relación de las áreas no-lineal se encontró entre las estructuras, lo que sugiere una relación de transmisión de sonido que incluye tanto la reducción de sonido y amplificación. Una compleja relación de las palancas se pudo observar originando una relación oscicular y articular asimétrica, lo que sugiere una función de amplificación de la transmisión del sonido inicial y también un destino reductor final para su conducción.