The symptoms of OME are due at least in part to both inflammation of the middle ear mucosa and/or to eustachian tube (ET) obstruction (dysfunction) with failure to ventilate the middle ear. This is caused by allergic reactions, and local inflammation associated with persistence of pathogenic bacteria or bacterial components.[83] Friedman[40] used a double-blind protocol to show that intranasal pollen challenge of allergic individuals produced allergic rhinitis followed by ET obstruction. Placebo patients did not obstruct. He demonstrated that allergic reactions in the nose and nasopharynx inhibit even transient dilations of the eustachian tube during swallowing. Double-blind protocols also show that provocative intranasal challenges with allergens or histamine produce severe functional obstruction of the eustachian tube.[120],[34],[1],[10]
Fireman and Bluestone demonstrated that exposure of the nose to antigen leads to ET obstruction and is dose dependent. This type of dose dependent mucosal edema is acutely produced only by inflammatory mediators such as bradykinin, histamine, leukotrienes, or granular proteins from the eosinophil.[98],[142] which are the result of an allergic reaction in the middle ear itself.
The bottom of the eustachian tube can also be obstgructed by adenoids sitting in the back of the nose. Adenoidectomy must also be considered as a treatment for OME.