Serous otitis media is a term which is used to describe a collection of fluid in the middle ear. This may be a recent onset (acute) or may be long standing (chronic).
Serous otitis media is the most common cause of hearing loss in children. Fortunately, the hearing loss associated with this condition usually is not permanent. Proper treatment restores the hearing to a normal level and prevents secondary complications, which can give rise to a more serious problem.
In serous otitis media, the external and inner ear and hearing nerve are normal. The problem stems from inadequate function of the Eustachian tube. The tube becomes blocked and does not allow air to fill the middle ear space. Subsequently, fluid (called serous fluid) forms from the middle ear lining and collects in the space (fig. 2). The presence of this serous fluid limits or “dampens” the vibration of the eardrum and causes a mild to moderate hearing impairment. This fluid makes the ear more susceptible to recurrent ear infections in many children. The trapped fluid is an ideal place for bacteria to grow and reproduce rapidly. Therefore, bacteria entering the middle ear space easily cause a purulent infection; the pus produced then exerts pressure on the eardrum with resultant pain (earache).
However, serous otitis media may be present without recurrent ear infections and a mild hearing loss may be the only sign of its presence.
Acute serous otitis media is usually the result of blockage of the eustachian tube from an upper respiratory infection or an attack of nasal allergy. In the presence of bacteria this fluid may become infected leading to an acute suppurative otitis media (infected or abscessed middle ear).
When infection does not develop the fluid remains in the middle ear until the eustachian tube again begins to function properly, at which time the fluid is absorbed or drains down the tube into the back of the throat.
Chronic serous otitis media may result from long standing eustachian tube blockage or from a thickening of the fluids so that it cannot be absorbed or drained down the tube. This chronic condition is usually associated with a hearing impairment. There may be recurrent ear pain, especially when the individual catches a cold. Serous otitis may persist for many years without producing any permanent damage to the middle ear mechanism. Presence of fluid in the middle ear, however, makes it very susceptible to recurrent acute infections. These recurrent infections may result in middle ear damage.
CAUSE OF SEROUS OTITIS MEDIA
Serous otitis media may result from any condition that interferes with the periodic opening and closing of the eustachian tube. The causes may be congenital (present at birth), may be due to infection or allergy, or may be due to mechanical blockage of the tube.