How does otitis media (AOM) develop?

Updated: Sep 25, 2019
  • Author: John D Donaldson, MD, FRCSC, FACS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

The infection is usually of viral origin, but allergic and other inflammatory conditions involving the eustachian tube may create a similar outcome. Inflammation in the nasopharynx extends to the medial end of the eustachian tube, creating stasis and inflammation, which, in turn, alter the pressure within the middle ear. These changes may be either negative (most common) or positive, relative to ambient pressure.

Stasis also permits pathogenic bacteria to colonize the normally sterile middle ear space through direct extension from the nasopharynx by reflux, aspiration, or active insufflation.

The response is the establishment of an acute inflammatory reaction characterized by typical vasodilatation, exudation, leukocyte invasion, phagocytosis, and local immunologic responses within the middle ear cleft, which yields the clinical pattern of AOM.


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