This can result in formation of a perilymphatic fistula, leading to loss of inner ear fluid with consequent hearing loss and vertigo. In addition, inner ear barotrauma may occur due to rupture of the round and oval membranes separating the middle and inner ear. Large pressure differences between the middle ear and the surrounding water can lead to the same injuries as with flying. This can lead to bruising of or bleeding into the tympanic membrane, formation of fluid exudates in the middle ear, and occasionally TM rupture.ĭiving - While pressure changes due to flying are less than one atmosphere, pressure changes with diving can be several atmospheres, resulting in more severe injuries. When this does not occur (usually due to a non-functioning Eustachian tube), the tympanic membrane (TM) is forced medially and stretched. The opposite occurs on descent air pressure has to increase in the middle ear to balance the increase in atmospheric pressure. Normally this change is gradual and is equilibrated by swallowing or absorption of air by the middle ear mucosa. Outside barometric pressure decreases as the plane ascends. Commercial aircraft have pressurized cabins, with the pressure generally equal to that at 7000 to 10,000 feet, not sea level. In addition, slower equilibration may occur with absorption of the gases by the middle ear mucosa.įlying - The most frequently encountered cause of ear barotrauma is flying. Generally, buildup of pressure inside the middle ear will resolve, as air can usually force its way out of the middle ear via the Eustachian tube. Concomitant infection in the nose or nasopharynx may spread to the middle ear with this maneuver. When the pressure difference is great, air can be forced through the Eustachian tube into the middle ear to equalize pressure. In some situations, positive pressure can be generated in the nose and nasopharynx (Valsalva maneuver) to try to overcome the Eustachian tube barrier. (See "Eustachian tube dysfunction", section on 'Pathophysiology of Eustachian tube dysfunction'.) Increased tissue mass in the nasopharynx, enlarged adenoids, and nasopharyngeal tumors also may obstruct adequate middle ear ventilation. This swelling can impede normal Eustachian tube function and lead to difficulties in equalizing middle ear pressure, thereby predisposing to ear barotrauma. Swelling of the mucosa in the nasopharynx or within the Eustachian tube may occur with infection (eg, upper respiratory infection or acute otitis media) or edema (eg, due to allergies or acid reflux). The Eustachian tube also needs to be closed most of the time to prevent TM motion with respiration.Įustachian tube dysfunction - Dysfunction of the Eustachian tube can occur for a variety of reasons. This ensures that the Eustachian tube is only open when it is protected against reflux from the oral cavity by elevation of the soft palate to close off the nasopharynx. These muscles elevate and tense the palate and simultaneously open the Eustachian tube. The Eustachian tube opens momentarily during swallowing or yawning due to actions of the levator veli palati and the tensor veli palati muscles. The anterior half is made of soft tissue that is mucosa-lined it is normally collapsed.The posterior half leading from the ear is a bony tube lined with mucosa that does not change shape.The Eustachian tube extends from the middle ear to the nasopharynx and is made up of two parts ( figure 1): When the Eustachian tube does not function adequately, pressure differences develop between the middle ear and the outside environment, resulting in ear barotrauma. This happens normally when one swallows or yawns, during which time airflow can occur. During normal physiologic function, air in the middle ear is absorbed slowly by the lining mucous membranes and is continually replaced by the opening of the Eustachian tube. Pressure within the middle ear has to match that of the environment for the TM to vibrate normally. PATHOGENESIS - The middle ear is an air-filled space, separated from the external environment by the tympanic membrane (TM) laterally and the Eustachian tube anteromedially ( figure 1). Other issues related to Eustachian tube dysfunction are discussed in detail elsewhere. This topic will focus on the clinical manifestations, diagnosis, and treatment of ear barotrauma. INTRODUCTION - Ear barotrauma occurs when the tympanic membrane (TM) is distorted due to pressure differences between the middle ear and the outside environment, leading to discomfort, hearing loss, and injury.
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