Eustachian tube function and retraction of the tympanic membrane

The medial displacement of the tympanic membrane or the retracted tympanic membrane is a common clinical finding. Also, retractions are looked upon as the precursor of middle ear cholesteatoma. In current otologic literature there seems to be some dispute whether the retractions of the tympanic membrane are caused by negative intratympanic air pressure or by shrinkage of middle ear adhesions pulling the tympanic membrane or part of it medially. In this study only ears with posterior/superior retractions of the tympanic membrane were investigated. Tympanometry revealed that only 33% of the ears did have middle ear pressure within +/- 100 mm H2O. After insertion of a polyethylene tube through the tympanic membrane, the eustachian tube function was tested using the air pressure equalization technique. None of the ears could change the negative air pressure upon swallowing. Planometric measurements on the x-ray of the mastoid air cell system of the present material deviate from those of a normal material, indicating a significantly smaller air volume in the present material. It may be concluded that dysfunction of the eustachian tube and a small air volume of the mastoid are characteristic features of an ear with posterior/superior retraction of the tympanic membrane.