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:

1. Jamal A et al. Etiology, Diagnosis, Complications, and Management of Acute Otitis Media in Children. Cureus. 2022 Aug 15;14(8)
2. Danishyar A. Acute Otitis Media. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan. 2023 Apr 15.