What is the sequence of events that result in otitis media with effusion?

Otitis media is also referred to as serous (secretory) otitis media. This condition is characterized by the accumulation of fluid in the middle ear cavity. The Eustachian tube (also called the auditory tube or pharyngotympanic tube) ceases to function normally. Because the Eustachian tube is responsible for aerating the middle ear, the middle ear space becomes anaerobic as tissues absorb the available oxygen. At the same time, dysfunction of the Eustachian tube may impede the equalization of pressure between the middle ear space and the environment.

In either case, a relatively negative pressure may develop in the middle ear tissues, which is called transudation. In addition, this negative air pressure can also cause drainage of mucus from the middle ear tissue. This state, termed middle ear effusion, interferes with sound transmission, which in turn, reduces the movement of the tympanic membrane.