by Warren P. Silberstein, M.D.
To understand middle ear infections you need to know a little anatomy.
The middle ear (shown in yellow) is essentially a closed space except for the Eustachian tube (shown in red) that allows air in and out of the middle ear. The middle ear is like an amplification chamber. There are 3 little bones (shown in white) attached to each other in the middle ear. The first bone is attached to the drum and the last bone is attached to the inner ear. When a sound wave vibrates the ear drum (also known as tympanic membrane - shown in blue), the little bones vibrate, transmitting the sounds to the inner ear where little "hairs" vibrate and translate the vibrations into a nerve impulse to send to the brain. In order for the middle ear to function properly, it must be filled with air and the air pressure must be the same on both sides of the drum. The Eustachian tube controls the air pressure by allowing air into the middle ear. Getting air out of the middle ear is never a problem because the middle ear is surrounded by porous bone which absorbs the air like a sponge. So what it boils down to, is that for the middle ear to function properly, the Eustachian tube must allow air into the middle ear whenever necessary to equilibrate (make equal) the pressure on both sides of the drum.
Understanding Eustachian tube function is the key to understanding most middle ear problems. The Eustachian tube is a narrow muscular tube that can allow air into the middle ear, but it isn't wide open allowing air in freely. That's why it takes time for your ear to adjust to pressure changes when you go up in a fast elevator or go underground into a tunnel. Swallowing and yawning help to open the Eustachian tube. When your ears feel stuffed you can try yawning or swallowing to allow air in. It makes your ears pop.
In the picture you can see where one end of the Eustachian tube is. The other end is in the nasopharynx, the place behind the nose where the nose and throat join. That's the very same place where you get inflamed tissues and mucus when you have a cold. As a result, the Eustachian tube gets congested when you have a cold and doesn't allow air into the middle ear freely. This results is the stuffed ears and popping most people experience with colds. The adenoids, which are lymphoid tissue just like the tonsils, are also in the nasopharynx. Large adenoids can press on the Eustachian tubes interfering with their proper function. And adenoids tend to get larger when they become inflamed during upper respiratory infections.
Since one end of the Eustachian tube is in the nasopharynx, and swallowing opens the Eustachian tube, one thing to keep in mind is that infants who drink milk flat on their backs are at higher risk for developing middle ear infections because milk may get into the entrance of the Eustachian tube and cause it to become inflamed.
For little children a congested Eustachian tube is a big problem. A child's Eustachian tube is smaller than an adult's, and, because of differences in facial shape and structure, a child's Eustachian tube is much more prone to obstruction than an adult's. When the Eustachian tube doesn't allow air into the middle ear for a long time, since the porous bone surrounding the middle ear absorbs air from the middle ear, a vacuum develops. If the vacuum persists long enough, the pressure of the vacuum sucks fluid into the middle ear from the surrounding blood supply. This is known as serous (not serious) otitis media or middle ear effusion, but most parents know it as "there's still fluid in the middle ear!"
Persistent middle ear fluid is a problem in its own right. When the middle ear is filled with fluid instead of air it doesn't function to amplify sound. Sound waves don't travel as well through fluid as air and the fluid prevents the ear drum from vibrating freely. As a result, children with middle ear fluid don't hear well. Older children may turn up the volume of the TV and say "what?" a lot. Younger children who are in the process of learning to speak may have significant problems and delays in developing language.
Middle ear fluid is a great place for germs to grow. It is possible to have middle ear fluid for a long time without developing an ear infection, but once bacteria get into the middle ear fluid, they begin to grow. This results in inflammation in the middle ear. Pus forms in the middle ear. If the pressure builds up quickly the drum is stretched causing severe pain. In extreme cases the drum may rupture with leakage of pus and blood. Antibiotics are the usual treatment to kill the germs that caused the infection, but antibiotics don't do anything to change the conditions that led to the ear infection in the first place. Middle ear fluid and Eustachian tube obstruction may remain after an ear infection has been successfully treated. Some ear infections may not resolve on just one course of antibiotics. In addition, the inflammation in the middle ear caused by the ear infection results in the other end of the Eustachian tube becoming narrowed or even obstructed. It can take 6 to 8 weeks for complete healing of the middle ear and the Eustachian tube leaving the affected child more prone to another ear infection. If the poor child has another cold on top of that it becomes very likely that he will have another ear infection. For some children it becomes a vicious cycle of persistent middle ear fluid and one ear infection after another. But take heart. The situation is not hopeless.
The usual approach to treatment can be divided into two categories: medical and surgical. Children who have recurrent ear infections or persistent middle ear fluid should be followed closely by their pediatricians to determine which intervention is appropriate.
If a child returns to the pediatrician for follow up and still has an infection or develops an infection quickly after treatment, usually the pediatrician will switch antibiotics to avoid the possibility of resistant germs. To avoid resistant germs developing in the environment, however, treatment for the first ear infection shouldn't be started with the newest antibiotic. Unfortunately, Amoxicillin, which is an excellent choice for initial treatment, has gotten a reputation for not working well because, if it's the first drug used, it's always the one that didn't work when a child needs additional treatment. But as explained above, middle ear infections may not resolve because antibiotics don't change the conditions that resulted in the infection in the first place. For a more complete discussion of antibiotics see my article Antibiotics. Are They Wonder Drugs?.
Once a child's ear infection has cleared, if it has required multiple courses of antibiotics or there is persistent middle ear fluid, the pediatrician may wish to try the child on a prolonged course of antibiotics given only once daily. These antibiotics don't do anything to clear the middle ear fluid, but if they prevent reinfection of the ear, the cycle of fluid and reinfection can be broken. The usual course of prophylactic antibiotics is once daily for one or more months. The disadvantages to this method include the need for prolonged medication with potential side effects and a potential adverse effect on the number of antibiotic resistant organisms in the environment.
Other medications have been used unsuccessfully in the battle against middle ear infections. Since congestion can lead to middle ear fluid it makes sense to give children decongestants if they are stuffy, but once middle ear fluid has developed, decongestants don't do anything to reduce the fluid. The FDA has classified decongestants as ineffective in the treatment of middle ear infections. Since the middle ear becomes inflamed by the infection, steroids have been tried for their potent anti-inflammatory effect, but they have also proven ineffective in the battle against ear infections.
For children who have failed at medical therapy or don't tolerate medical therapy because of side effects, surgical management may be the best option to prevent recurrent middle ear infections. If a child has large adenoids, removal of the adenoids may be sufficient to solve the problem. The placement of ventilation tubes through the drum allows air into the middle ear through the tube, bypassing the malfunctioning Eustachian tube. The disadvantages to surgical treatment include the need for general anesthesia, possible bleeding after adenoidectomy, and the fact that with tubes a child cannot immerse his head in water without water tight ear plugs. Since surgery is a big step parents should also be aware that it doesn't carry a 100% guarantee of avoiding future ear infections. Sometimes the tubes come out early and sometimes when the tubes come out the ear drum doesn't heal and requires additional surgery. In spite of these realistic precautions, it is fair to say that many parents whose children have had recurrent ear infections have been delighted to finally have a healthy child after the surgery.
No discussion would be complete without a little controversy and a look at what's new. Because of recent trends in antibiotic resistance pediatricians are looking at the possibility of not treating all ear infections with antibiotics. Not all ear infections are caused by bacteria. Sometimes the infection is caused by a virus, and viruses don't respond to antibiotics. The decision regarding use of antibiotics would have to be made on the basis of fever, the appearance of the ear drum, and the past history of ear infections since children with chronic ear problems are not the best candidates for no treatment. The benefit to this approach is that it will hopefully safeguard antibiotics for when they are really needed. The disadvantage is that the incidence of secondary complications such as mastoiditis (infection in the bones behind the ear) and meningitis will increase.
You may have noticed that I refer to ear infections as middle ear infections. An inflammation or infection of the outer ear is entirely different. Swimmer's ear is a common example of otitis externa (outer ear infection). Since the ear canal is inflamed, swimmer's ear is very painful to touch, whereas middle ear infections are generally not tender to touch. Swimmer's ear is treated with antibiotic/anti-inflammatory drops.
Finally, What do you do when you child wakes up in the middle of the night screaming with an earache? A screaming child needs help, but don't panic! It's not an emergency. If you have a reasonable idea what's going on with your child and he's not too sick, your goal is to treat the pain. Antibiotics don't relieve pain so it isn't urgent to start them. If your doctor has prescribed anesthetic drops you may safely use them as long as the ear isn't draining. Alcohol acts as a local anesthetic and in a pinch you could even try vodka in the ear. Since Ibuprofen (Motrin, Advil) for children is now available without a prescription and is very effective for pain and fever it's worth keeping in the house. The dose is 1/2 teaspoon (2.5 ml.) which is 50 mg. of Ibuprofen per 11 pounds of body weight. A single dose should not exceed 4 teaspoons. The dose can be repeated every 6 to 8 hours with a maximum of 4 doses in 24 hours. If you make it through the night and you child has no pain in the morning you should still see your pediatrician because even if the pain is gone there may be an infection that requires treatment.
If you'd like to read another article about ear infections try the one at KidsHealth.org.
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