Pathology
- in otitis media there is an infection of the whole of the middle ear cleft, i.e. the Eustachian tube, tympanic cavity, attic, mastoid antrum and air cells. (1,2)
- colonization of nasopharynx with S. pneumoniae, H. influenzae, or M. catarrhalis predispose to otitis media
- this results in aspiration of infected inoculum through the eustachian tube into the middle ear space
- aspiration is promoted by following mechanisms
- nasal obstruction that increases the positive pressure in the nasopharyngeal space
- eustachian tube dysfunction that produces a negative pressure in the middle ear space
- the mucous membrane is thus invaded by organisms which cause inflammation, oedema and exudate - pus is a later consequence of bacterial infection.
- the Eustachian tube is closed by oedema and so prevents aeration and drainage
- the drum bulges due to increased pressure from the pus
- perforation of the tympanic membrane results, caused by necrosis. There is continual drainage of the ear until the infection resolves.
Reference:
- Jamal A et al. Etiology, Diagnosis, Complications, and Management of Acute Otitis Media in Children. Cureus. 2022 Aug 15;14(8)
- Danishyar A. Acute Otitis Media. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan. 2023 Apr 15.
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