The ear is divided into three parts; an external ear, a middle ear and an inner ear. Each part performs an important function in the process of hearing.
The external ear consists of an auricle and ear canal. These structures gather the sound and direct it towards the eardrum membrane.
The middle ear chamber lies between the external and inner ear. This chamber is connected to the back of the throat by the eustachian tube which serves as a pressure equalizing valve. The middle ear consists of an eardrum membrane and three small ear bones (ossicles); malleus (hammer), incus (anvil) and stapes (stirrup). These structures transmit sound vibrations to the inner ear. In so doing they act as a transformer, converting sound vibrations in the external ear canal into fluid waves in the inner ear. A disturbance of the eustachian tube, eardrum membrane or the ear bones may result in a conductive hearing impairment. This type of impairment is usually correctable medically or surgically.
The inner ear chamber contains the microscopic hearing nerve endings bathed in fluid. Inner ear fluid waves stimulate the delicate nerve endings which in turn transmit sound energy to the brain where it is interpreted. A disturbance in the inner ear fluid or nerve endings may result in a sensorineural (nerve) hearing impairment. This type of impairment is not correctable.
Serous otitis media is the term we use to describe a collection of fluid in the middle ear. This may be acute or chronic.
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 until the eustachian tube again begins to function normally, at which time the fluid is absorbed or drains down the tube into the throat.
Chronic serous otitis media may result from long standing eustachian tube blockage, or from thickening of the fluids so that it cannot be absorbed or drained down the tube. This chronic condition is usually associated with hearing impairment. There may be recurrent ear pain, especially when the individual catches a cold. Fortunately serous otitis media may persist for many years without producing any permanent damage to the middle ear mechanism. The 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.
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 blockage of the tube by adenoids.
The size and shape of the eustachian tube is different in children than in adults. This accounts for the fact that serous otitis media is more common in very young children. Some children inherit small eustachian tubes from their parents; this accounts in part for the familial tendency to middle ear infection. As the child matures, the eustachian tube usually assumes a more adult shape.
The eustachian tube is a narrow, one and a half inch long channel connecting the middle ear with the nasopharynx, the upper throat area just above the palate, in back of the nose.
The eustachian tube functions as a pressure equalizing valve for the middle ear which is normally filled with air. When functioning properly the eustachian tube opens for a fraction of a second periodically (about once every three minutes) in response to swallowing or yawning. In so doing it allows air into the middle ear to replace air that has been absorbed by the middle ear lining (mucous membrane) or to equalize pressure changes occurring on altitude changes. Anything that interferes with this periodic opening and closing of the eustachian tube may result in hearing impairment or other ear symptoms.
Obstruction or blockage of the eustachian tube results in a negative middle ear pressure, with retraction (sucking in) or the eardrum membrane. In the adult this is usually accompanied by some ear discomfort, a fullness or pressure feeling and may result in a mild hearing impairment and head noise (tinnitus). There may be no symptoms in children. If the obstruction is prolonged, fluid may be drawn from the mucous membrane of the middle ear, creating a condition we call serous otitis media (fluid in the middle ear). This occurs frequently in children in connection with an upper respiratory infection and accounts for the hearing impairment associated with this condition.
On occasions just the opposite from blockage occurs; the tube remains open for prolonged periods. This is called abnormal patency of the eustachian tube. This condition is less common than serous otitis media and occurs primarily in adults. Because the tube is constantly open the patient may hear himself breathe and hears his voice reverberate. Fullness and a blocked feeling are not uncommon. Abnormal patency of the eustachian tube is annoying but does not produce hearing impairment.
Serous otitis media is more common in the child with a cleft palate. This is due to the fact that the muscles that move the palate also open the eustachian tube. These muscles are deficient or abnormal in the cleft palate child.
The lining membrane (mucous membrane) of the middle ear and eustachian tube is connected with, and is the same as, the membrane of the nose, sinuses and throat. Infection of these areas results in mucous membrane swelling which in turn may result in eustachian tube obstruction.
Allergic reactions in the nose and throat result in mucous membrane swelling, and this swelling may also affect the eustachian tube. This reaction may be acute, as in a hay fever type reaction, or may be chronic, as in many varieties of "chronic sinusitis".
The adenoids are located in the nasopharynx, in the area around and between the eustachian tube openings. When enlarged, the adenoids may block the eustachian tube opening.
Treatment of acute serous otitis media is medical, and is directed towards treatment of the upper respiratory infection or allergy attacks. This may include antibiotics, antihistaminics (anti-allergy drugs), decongestants (drugs to decrease mucous membrane swelling) and nasal sprays.
In the presence of an upper respiratory infection, such as a cold, tonsillitis or sinusitis, fluid in the middle ear may become infected. This results in what is commonly called an abscessed ear or an infected ear.
The infected fluid (pus) in the middle ear may cause severe pain. If examination reveals that there is considerable ear pressure a myringotomy (incision of the eardrum membrane) may be necessary to relieve the abscess, and the pain. In many cases antibiotic treatment will suffice.
Should myringotomy be necessary the ear may drain pus and blood for up to a week. The drum membrane then heals and the hearing usually returns to normal within three to four weeks.
Antibiotic treatment, with or without myringotomy, usually results in normal middle ear function within three to four weeks. During the healing period there are varying degrees of ear pressure, popping, clicking and fluctuation of hearing, occasionally with shooting pains in the ear.
Resolution of the acute infection occasionally leaves the patient with uninfected fluid in the middle ear. This is called chronic serous otitis media.
Treatment of chronic serous otitis media may be either medical or surgical.
As the acute upper respiratory infection subsides it may leave the patient with a chronic sinus infection. Pus from the sinuses and nose drains over the eustachian tube opening in the nasopharynx resulting in persistent eustachian tube blockage. Antibiotic treatment may be indicated.
General health factors are particularly important in regard to the child's resistance to infection. A deficiency in some of the blood proteins may predispose to recurrent infections and prolonged colds. Periodic injections of gamma globulin may be indicated.
Allergy is often a major factor in the development of persistence of serous otitis media. Mild cases can be treated with antihistaminic drugs. More persistent cases may require allergic evaluation and treatment, including injection treatment.
In connection with medical treatment we may recommend eustachian tube inflation, the blowing of air through the nose into the obstructed eustachian tube and middle ear to help relieve the congestion and reestablish middle ear ventilation. This is done by the Valsalva maneuver or by Politzerization.
The Valsalva maneuver is accomplished by forcibly blowing air into the middle ear while holding the nose, often called "popping the ear". This should not be done, however, if there is a cold and nasal discharge.
Politzerization is accomplished by blowing air with a special syringe (middle ear inflator) into one nostril while blocking the other, and at the same time swallowing. This forces the air into the eustachian tube and middle ear. This likewise should not be performed when a cold is present.
The primary objective of surgical treatment of chronic serous otitis media is to reestablish ventilation of the middle ear, keeping the hearing at a normal level and preventing recurrent infection that might damage the eardrum membrane and middle ear bones. This involves myringotomy with insertion of a ventilation tube and, at times, adenoidectomy.
Myringotomy (an incision in the eardrum membrane) is performed to remove middle ear fluid. A hollow plastic tube (ventilation tube) is inserted to prevent the incision from healing and to insure middle ear ventilation. The ventilation tube temporarily takes the place of the eustachian tube in equalizing middle ear pressure. This plastic tube usually remains in place for three to nine months during which time the eustachian tube blockage should subside. When the tube dislodges, the eardrum heals; the eustachian tube then resumes its normal pressure equalizing function.
In rare cases the drum membrane does not heal following dislodgement of the tube. The perforation may be repaired at a later date if this occurs.
In adults, myringotomy and insertion of a ventilation tube is usually performed in the clinic under local anesthesia. In children general anesthesia is required. The adenoids can be removed if enlarged.
More often than not when the ventilation tube dislodges there is no further middle ear ventilation problem. Should serous otitis media recur, reinsertion of a tube may be necessary. In some difficult cases it is necessary to insert a more permanent type of tube, the "mesh" ventilation tube. This tube is more difficult to insert but frequently will remain in place until removed. In children, removal may require an anesthetic. At times a permanent drum membrane perforation (hole in the eardrum) develops when the tube is dislodged or removed. If this perforation persists it can be repaired at a later date when the eustachian tube blockage has subsided.
When a ventilation tube is in place the patient may carry on normal activities, with the exception that he must not allow water to enter the ear canal. Your doctor may recommend an ear plug for use when showering, washing the hair or swimming.