Tympanogram is also used to measure the improvement of middle ear function following interventions for Eustachian tube dysfunction. ![]() Tympanogram is another test related to middle ear function that measures tympanic membrane compliance, with an abnormal tympanogram finding indicating increased pressure within the middle ear. Another imaging study that shows promising results in diagnosing Eustachian tube dysfunction is scintigraphy, which uses radiolabeled albumin tracers introduced through the tympanic membrane to visualize the patency of drainage from the middle ear. Studies using CT imaging show a reduced cross-sectional area of the osseous portion of the Eustachian tube in patients with documented dysfunction. Cases of unilateral dysfunction demonstrated normal opening on the unaffected side and failure to open on the affected side. One study, using real-time MRI, was able to visualize the Eustachian tube opening with the Valsalva maneuver in patients with documented dysfunction. In addition, various imaging studies can aid clinical examination in diagnosing dysfunction. Ideally, a full clinical assessment should include the use of an otoscope, Rinne and Weber tuning forks or pure tone audiometry, and nasopharyngoscopy. Diagnosis is based on a clinical exam and symptoms specific to Eustachian tube dysfunction. The diagnosis of Eustachian tube dysfunction is poorly defined, with no existing comprehensive guidelines. This process is enhanced as the tube matures and becomes more oblique in angle, allowing gravity to play a role in the drainage process. Īlso of importance in the proper function of the Eustachian tube is the mucociliary clearance of middle ear secretions to the nasopharynx. It is these surfactants that aid in reducing the surface tension of the ET lumen and thus reduce the work required to dilate the tube. Of note, tubal dilation is facilitated by the presence of surfactants, surface tension-reducing substances found in the mucus of the ET. Intermittent brief tubal dilation of the ET occurs multiple times per day, occurring approximately 1.4 times/minute and remaining open for approximately 0.4 seconds. Two additional muscles associated with the Eustachian tube that have not been shown to play a significant role in the opening of the lumen include the tensor tympani and salpingopharyngeus muscles. This mechanism also clarifies why exaggerated Eustachian tube dysfunction will result in hearing deficits if a gas exchange deficit occurs in the middle ear, causing the tympanic membrane to tauten. This explains why dilation of the Eustachian tube allows air at atmospheric pressure to equilibrate with the lower partial pressures of gas in the middle ear that develop. Carbon dioxide and oxygen readily pass through the venous capillary membranes, creating a net pressure vacuum in relation to atmospheric pressure. The pressure discrepancy between the middle ear and the atmosphere is due to the diffusion of atmospheric gases across venous capillary cell membranes in the middle ear. Simultaneous contractions of these muscles during swallowing or yawning allow air to pass through the ET to equilibrate pressure in the middle ear with the atmosphere. ![]() ![]() Contraction of the levator veli palatini results in elevation of the soft palate and medial rotation of the cartilaginous lamina. The tensor veli palatini contracts the anterolateral wall to cause dilation and opening of the distal Eustachian tube. ![]() While the Eustachian tube is closed at rest, it relies on its interaction with two muscles to help facilitate its opening the tensor veli palatini and the levator veli palatini.
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