Pathogenesis of experimental otitis media with effusion caused by a combination of eustachian tube dysfunction and immunosuppression.

Inflammatory factors appear to play an important role in the development of otitis media with effusion (OME). However, otitis media experimentally induced by endotoxin injection or secondary immunoresponse was not persistent. In order to produce refractory OME, two pathologic conditions were necessarily combined: tubal ventilatory dysfunction and suppression of the immunologic defense mechanism by immunosuppressive drugs. In the presence of these two pathologic conditions, all cases that evidenced negative middle ear pressure due to tubal dysfunction developed OME. In the control group with either tubal dysfunction or immunosuppression alone, only 1 of 20 ears developed OME. Transtubal infection due to negative middle ear pressure caused by tubal ventilatory dysfunction may be one of the most important etiologic factors in OME.