Comparison of eardrum mobility in acute otitis media and otitis media with effusion models.

Objective: To investigate the eardrum mobility difference between acute otitis media (AOM) and experimental otitis media with effusion (OME). Thirty-three Hartley guinea pigs were included in this study. The AOM and OME were created by transbullar injection of Streptococcus pneumoniae and lipopolysaccharide into the middle ear, respectively.

Methods: Three days after inoculation, the morphologic changes of the middle ear were assessed with otoscopy and histologic sections. Vibrations of the tympanic membrane (TM) at umbo in response to pure tone sound were measured using laser Doppler vibrometry.

Results: The purulent effusion, ossicular adhesion, and thickened TM and middle ear mucosa were observed in the AOM ears, and the OME ears had serous effusion and less thickened TM and mucosa in the middle ear. The displacement of TM in AOM was lower than that in OME ears, especially at 0.2 to 4 kHz.

Conclusions: The TM mobility difference between the AOM and OME ears were mainly caused by the middle ear ossicular structure changes during the bacterial infection in AOM.