In most instances it is idiopathic. Adhesion formation in the nasopharynx following adenoidectomy or radiotherapy also may predispose to a patulous tube. Other predisposing factors include fatigue, stress, anxiety, exercise, and temporomandibular joint syndrome. Under normal resting conditions, the eustachian tube is closed and only opens with swallowing or autoinflation. In normal individuals, closure of the eustachian tube is maintained by luminal and extraluminal factors, which include intrinsic elasticity of the tube, surface tension of moist luminal surface, and extraluminal tissue pressure.
E affect surfactant production.
Scarring in postnasal space following adenoidectomy may result in traction of the tube in a patent position. Autophony is the most frequent symptom associated with the patulous tube. Vertigo and hearing loss also can occur because patulous eustachian tube allows excessive pressure changes to occur in the middle ear, which are then transmitted to the inner ear through ossicular movement. Some patients may have difficulty eating, as the noise of chewing is transmitted to the ear. Patulous eustachian tube often is misdiagnosed because symptoms mimic those of middle ear effusion.