[Eustachian tube and middle ear mechanics]

Abstract

Even the most sophisticated prostheses for reconstruction of the ossicular chain do not work in the presence of Eustachian tube dysfunction. This review gives an update on the mechanisms of middle ear pressure regulation and middle ear ventilation, as well as methods for measuring the opening and closing function of the Eustachian tube. So far, in most tube function tests pressures are applied far beyond the physiological range in order to open the tube or force it to open. New methods like sonotubometry with perfect sequences (PSEQ) or the application of pressure in the nasopharynx with the Estève technique seem very promising. However, these measurements only provide snapshots of tube function. Presently, new tests are being developed for long-term measurements even in cases with perforated tympanic membranes. Attempts to improve impaired tube function have recently included laser surgery and balloon tuboplasty, yielding positive long-term results requiring verification in larger controlled studies. Eustachian tube dysfunction does not only mean blockage but can also include abnormal patencies of the Eustachian tube, for which new approaches are discussed here. In the case of suspected tube dysfunction, cartilage should be used to avoid early tympanic retraction or recurrent perforation; external ventilation using ventilation tubes should be considered.