Aeration in chronic otitis media.

The mastoid air cell system must be looked upon as an air reservoir. The tympanic membrane is an air pressure regulator. The smaller the air volume of the mastoid the more pronounced is the volume displacement of the tympanic membrane. The more inefficient the Eustachian tube function, the more pronounced is the tympanic membrane displacement. The significance of these factors must be considered not only when discussing the etiology of chronic otitis media including cholesteatoma, but also when it comes to selecting procedures in restoring middle ear anatomy and physiology in chronic middle ear surgical disease.