The middle ear is the space behind the eardrum. It is roughly the size of an aspirin tablet, and it transmits sound from the air to the inner ear, where sounds are converted into nerve impulses. Efficient middle ear function is vital to good hearing.

Illustration from University of Washington Medical Center Otolaryngology-Head and Neck Clinic

Their web page about otitis media

contains a lot of well-written information, but some of the concepts are outdated.

Normally the middle ear is filled with air. In most children, at one time or another, the air will be replaced by fluid. Usually that occurs when the eustachian tube--the tube that connects the middle ear to the nasopharynx, the space behind the nose--fails to allow air up to the middle ear to replace the air that is constantly being absorbed there. A child's eustachian tube is inefficient because it isn't fully developed, and it may not equalize the pressure, especially if there is swelling due to a cold. As the air is absorbed and the pressure goes down, fluid is sucked into the middle ear space. Eventually the cells of the middle ear may begin to actively secrete fluid. (There is some controversy about the exact mechanism; treatments based on this explanation do work.)

Fluid can also remain in the middle ear following an infection. Once the bacteria are killed, the middle ear is left filled with sterile fluid. An adult with a normally functioning eustachian tube should be rid of the fluid in about a week, but it can take a child much longer to eliminate the fluid. If the fluid is still present at eight weeks, there is still some chance that it will clear. After twelve weeks, it's probably going to stay. Sometimes the fluid becomes infected again and again. This shouldn't be surprising; a clean, dry middle ear is relatively resistant to infection, but fluid provides an excellent culture medium for bacteria. Unfortunately, each infection seems to "reset" the fluid and makes it less likely to clear up.

An infection of the middle ear usually causes pain and fever, although with very young children it is often difficult to tell what is bothering them. Fluid may well cause no symptoms, and that's why school systems routinely test their students' hearing.

EFFECTS OF FLUID

Why is fluid such a problem? As you would expect, it interferes with hearing. The eardrum is supposed to have air on both sides. If one side is "underwater," naturally that will limit the eardrum's ability to vibrate. Even a mild hearing loss can interfere with a young child's speech development, and the resulting speech problems may be permanent. Even a mild hearing loss can make it difficult for an older child to do well in school.

Given enough time, the fluid can eventually damage the eardrum and the delicate bones of the middle ear. Persistent fluid and negative pressure can produce a cholesteatoma, a destructive, chronically infected cyst of the ear. These complications take quite some time to develop; as far as I know, nobody knows exactly how long.

MEDICAL TREATMENT

Often the only treatment required for fluid is time; many children will develop fluid, but most will clear it on their own. The American Academy of Otolaryngology-Head and Neck Surgery, the American Academy of Pediatrics, and the American Academy of Family Practice recently (2004) published a position paper which analyzes information from 172 different journal articles. Their conclusions about medication are "based on systematic review of randomized, controlled trials and preponderance of harm over benefit." That is, they've looked at well-designed clinical studies and found that medication for fluid is more likely to harm than to help. This is important, so here's the recommendation in the committee's own words:

Antihistamines and decongestants are ineffective for OME

[otitis media with effusion, or fluid] and are not recommended

for treatment. Antimicrobials and corticosteroids do not have long-term

efficacy and are not recommended for routine management.

The role of allergy treatment is uncertain. Some researchers feel that allergy is often an important part of the problem; others feel that allergy has little or nothing to do with middle ear fluid. Allergy treatment probably can't get rid of established fluid, but it may reduce future problems in children who have had trouble with fluid.

SURGICAL TREATMENT

If medication fails, the next step is myringotomy with tubes--making a tiny incision in the eardrum and inserting a tiny plastic tube to keep the incision open. The idea is not so much to remove fluid as to allow air into the middle ear. Since the eustachian tube isn't supplying air the way it should, the ventilating tube fulfills its function.

FOLLOW-UP

With tubes, surgery isn't the end of the treatment, it's closer to the beginning. I'm responsible for my patients' ears, and I want to see my patients about every three months so I know what's happening with their ears and their tubes. And if there's a problem, call me. There is good evidence that children with tubes can swim without problems.

RISKS OF SURGERY

Like any operation, myringotomy with tubes does have potential complications. Young children require general anesthesia for the surgery, but because the operation is short the risk is low. The most common complication of tubes is drainage; a very large percentage of children with tubes will drain at least once. Usually this is easy to treat with drops, but about once a year I have to remove tubes because they just won't stop draining. Statistics vary quite a bit from one study to another, but supposedly tubes can cause a persistent perforation of the eardrum (which isn't nearly as bad as it sounds) in one case out of 200 and a cholesteatoma in one out of 600. I think that these are both overestimates, especially the second, but even if they're correct then the tubes are less likely to damage the ears than the fluid is. Tubes do tend to cause scarring, which rarely causes any problems long-term.

After the tubes come out--usually after about three to eighteen months--as many as 30 percent of patients will develop problems again and require tubes again. This doesn't mean that there was something wrong with the operation, it means that the ear continues to require artificial ventilation.

Sometimes the tubes just don't come out. There's a fair amount of disagreement over how long is too long, but I start getting concerned at about eighteen months, and I do sometimes have to remove tubes in the operating room.

OTHER TREATMENTS

Adenoidectomy probably helps in the management of middle ear fluid and can usefully be performed along with myringotomy and tubes in selected cases.

Almost all otolaryngologists agree that tonsillectomy is not helpful in the management of fluid. Patients who have tonsil problems severe enough to warrant surgery can have tonsillectomy at the same time as myringotomy and tubes.

Gastroesophageal reflux is probably a factor in some cases of middle ear fluid. Stomach proteins have actually been found in the middle ear! As far as I know, nobody is trying to treat fluid by treating reflux, although treating reflux probably helps in some cases of sinusitis and asthma. .

WHAT ABOUT LASER SURGERY?

Back when I wrote the first version of this material in 2001, if you had searched the web for information about otitis media you would have found many references to a procedure called Oto-LAM. The Sharplan company is now called Lumenis, and it's still making the necessary equipment. Laser myringotomy sounds like a great idea; it provides ventilation of the middle ear for two or three weeks, and it can be performed as an office procedure without a general anesthetic. Here's what they don't tell you at the Sharplan/Lumenis site: 1) It takes about an hour to make each eardrum numb. If the ears are infected, it takes two hours each. 2) Sharplan's visions of happy patients cheerfully holding still for the procedure are not quite accurate. In one study, 93% of patients under age 2 had to be forcibly restrained, 100% of patients from age 2 to age 4 had to be forcibly restrained, and 33% of patients over age 4 had to be restrained. In other words, it was probably not an enjoyable experience for the patients or their parents. 3) In 47% of patients, the fluid returned within two months.

As far as I know, nobody in the Detroit metropolitan area has the equipment for Oto-LAM and the nearest available facilities are in Chicago and Buffalo. If you think that Oto-Lam would be the best choice for your child, I can put you in touch with doctors who perform this procedure and I'll be happy to provide the necessary follow-up.