Current Clinical Methods, Indications and Interpretation of Eustachian Tube Function Tests

Abstract

Eustachian tube (ET) dysfunction is the most important factor in the pathogenesis of otitis media and related conditions. The importance of the function of the ET in relation to the middle ear-mastoid air cell system is compared to the critical role that laryngeal function has in its relation to the tracheobronchial-pulmonary system. However, because of its obscure location, the ET is not as easily assessed by clinical or laboratory methods as is the larynx, and therefore, its function is not as well understood. Most clinicians do not include ET function testing as part of their evaluation of patients with middle ear (ME) disease. Pneumatic otoscopy, the Toynbee test, tympanometry, the 9-step inflation-deflation tympanometric test, and the patulous tube test can be performed when the tympanic membrane is intact. The modified inflation-deflation test employing the pump-manometer of the electroacoustic impedance bridge can assess the function of the ET when the tympanic membrane is not intact. These tests are helpful in the diagnosis of the presence or absence of abnormal ET function; if a dysfunction is present, these tests help to determine whether or not the tube is obstructed (mechanically or functionally) or abnormally patent, and in some instances, the degree of the malfunction. Even though testing of the function of the ET in the clinical setting has severe limitations at present, and further research is needed, information can be gained which is useful in the diagnosis and management of ME disease. Failing to recognize and assess the function of the ET in relation to the ME and mastoid in selected patients is as irrational as ignoring the function of the larynx in patients with disease of the lower respiratory tract.