Change of ear mechanics in otitis media with effusion.

摘要

Otitis media with effusion (OME) is an inflammatory disease of the middle ear characterized by the presence of fluid in the middle ear cavity. OME is one of the most frequent diseases in children and causes most of conductive hearing loss. In this dissertation, the changes of mechanical movement of middle ear and cochlea in OME model created in human temporal bone and guinea pig were reported through the experimental measurements and modeling. The OME was simulated in temporal bones by injecting fluid and air pressure in the middle ear cavity. The animal OME model was created in guinea pigs by inoculating the middle ear with LPS and the OME model was evaluated with otoscopy, tympanometry, histology and post-experiment check of middle ear fluid. The displacements of the tympanic membrane and round window membrane in the middle ear and the displacement of basilar membrane in cochlea were measured using a laser Doppler vibrometer. The cochlear mechanics was also evaluated with measurements of auditory brainstem response (ABR) by correlation analysis with the basilar membrane movement. A 3-dimensional (3D) finite element model of guinea pig middle ear was created for future mechanics analysis in OME.;The results show that the middle ear effusion reduced the middle ear movement over the auditory frequencies and mainly at high frequencies. The middle ear pressure reduced the tympanic membrane movement mainly at low frequencies. The fluid and pressure effects on the tympanic membrane movement in fluid-pressure combination are not additive. The movement of basilar membrane was reduced in the ears with OME and the cochlear gain was reduced with the variation of middle ear transfer function. The ABR measurements show the variation of ABR was highly related to the change of cochlear mechanics, which indicates ABR could be a potential tool to evaluate cochlear mechanics in OME.;The major contribution of this project is to provide useful experimental data of sound transmission measured from the suitable OME model created in human temporal bones and guinea pig ears with biomedical engineering approaches. The conclusion of this study is that the middle ear and cochlear mechanics was affected by OME and change of middle ear and cochlear movement is frequency dependent and varied with survival times of OME. Results of this study will bring new insight of detection of OME with biomedical engineering techniques.