Tympanic membrane retraction usually occurs when a portion of the tympanic membrane becomes weakened and is pulled inwards by the negative pressure within the middle ear.
Pathology
As the tympanic membrane is pulled inwards (medially), it can become draped over the ossicles, resulting in a variety of symptoms.
Classification
The retraction can be subdivided based on severity 1:
- I: retraction
- II: retraction with incus contact
- III: middle ear atelectasis
- IV: adhesive otitis media
It can also be divided according to which part of the tympanic membrane is retracted 1:
- pars tensa retraction: retraction of the tense portion of the membrane is more common and more frequently associated with ossicular erosions, especially the long process of the incus
- pars flaccida (attic) retraction: retraction of the flaccid portion of the membrane predisposes to acquired cholesteatomas
