Patulous Eustachian Tubes

 

The Normal Function Of Eustachian Tubes

The normal eustachian tube is functionally collapsed at rest, with slight negative pressure present in the middle ear. It opens during swallowing, sneezing, and yawning. The eustachian tube is thought to close through passive reapproximation of the tubal walls by extrinsic forces and recoil of the elastic fibers.

The eustachian tube has three main functions: ventilation, drainage, and protection.

When the eustachian tube is open it allows ventilation of the middle ear and equalization of middle ear and atmospheric pressure.

It also allows the middle ear to clear unwanted secretions.

By staying physiologically obstructed, it protects the middle ear from nasopharyngeal secretions and sound.

Conditions interfering with normal eustachian tube function cover the pathologic spectrum from benign to malignant. Resultant middle ear complications can be the primary condition that the clinician needs to address, may be a sign of something more serious, or may have implications that will affect the outcome of surgical interventions.

Eustachian Tube Dysfunction

Obstructive disorders can be mechanical or functional.

Mechanical obstruction can be intrinsic due to intraluminal factors such as mucosal inflammation due to allergy or infection, or extrinsic obstruction resulting in compromise of the lumen. Extrinsic obstruction can be physiologic such as when the patient is supine, or may be caused by a mass lesion such as a neoplasm or an adenoidal mass.

Functional obstruction results from persistent collapse of the eustachian tube due to increased tubal compliance, an abnormal opening mechanism, or both. Functional obstruction is more common in infants and young children, and in many cases can be related to normal or abnormal developmental factors.

Patulous Eustachian Tubes

Patulous eustachian tubes often present a frustrating problem for patient.The incidence is reported to be between 0.3-6.6% of the general population.

Patients with patulous eustachian tubes complain of aural fullness, humming tinnitus, and autophony. They also may hear their own breath sounds, which is known as tympanophonia. The sound is synchronous with nasal respiration and resolves when the patient is supine or when upper respiratory tract inflammation occurs. The sounds may be aggravated by mastication.

Symptoms are usually absent when the patient is supine or relieved when the patient bends forward with the head between the knees. For this reason, patients should not be examined in a supine position. Physical examination may reveal a tympanic membrane that moves during forced breathing through one nostril, and an amorphic sound may be heard using a diagnostic tube in the patient's ear.

The eustachian tube is usually closed, and closure is maintained by the elasticity of its cartilage, mucosal lining, surrounding muscles and fat. Alteration of any of these anatomic components may cause patulous eustachian tubes.

Conditions associated with patulous eustachian tubes include: radiation therapy, hormonal therapy, pregnancy, nasal decongestants, fatigue, stress, and weight loss.

Patulous eustachian tubes in the most severe form may be patent at all times, whereas a less severe form has been reported, where the tube is anatomically closed at rest, but may open easily during exercises or in association with a decrease in peritubal extracellular fluid