Otitis media with effusion (OME) refers to fluid in the middle ear space, but without the symptoms of an acute infection. Children with acute otitis media (AOM) have fluid in the middle ear accompanied by signs or symptoms such as ear pain, redness of the eardrum, or fever. Children with AOM act sick, especially at night. Children with OME do not.

The fluid in OME is often thin and watery. "Glue ear" is a common name given to OME with thick, viscous effusion (fluid).

Causes

In the United States, there are over 25 million visits to pediatricians each year related to ear infections, making it the most common diagnosis for children. Almost every acute ear infection is followed by days or weeks of OME. In addition, many people develop OME without first having acute inflammation.

The cause of OME is improper functioning of the eustachian tube, a narrow channel that connects the inside of the ear to the back of the throat, just above the soft palate. This tube is a drainage conduit to prevent the build-up of secretions that are normally made in the middle ear. They drain down the tube and are swallowed. The tube also functions to keep the air space in the middle ear at the same pressure as the air around us. In this way, the eardrum can move freely, and our hearing is most effective.

When all is well, the tube is collapsed most of the time in order to protect the middle ear from the many organisms that live in the nose and mouth. Only upon swallowing does a tiny muscle open it briefly to equalize the pressures and drain the ear secretions. If any bacteria make it into the ear, the drainage mechanism, helped by little hair cells, should flush it out.

When the eustachian tube is partially blocked, fluid accumulates in the middle ear. Bacteria already there are trapped and begin to multiply.

Respiratory infections, irritants (especially cigarette smoke), and allergies can all inflame the lining of the tube, producing swelling and increased secretions. They can also cause enlargement of the adenoid glands near the opening of the tube, blocking flow at the outlet. Sudden increases in air pressure (during descent in an airplane or on a mountain road) can squeeze the floppy tube closed and create a relative vacuum in the ear. Drinking while lying on one's back can close the slit-like tube opening. Although a myriad of factors can lead to a blocked tube, getting water in a baby's ears won't.

The last two decades of the 20th century saw a dramatic rise in OME, largely due to increased pollution and the prevalence of early childhood day care (where children are exposed to many respiratory infections).

OME is most common in winter or early spring, but can occur at any time of year. The highest incidence is in children under 2 years old, but it can occur in people of any age.

Small children get more OME than older children or adults for several reasons: The tube is shorter, more horizontal, and straighter (quick and easy trip for the bacteria). The tube is floppier, with a tinier opening (easier to block). And young children get more colds (it takes time for the immune system to be able to recognize and ward off cold viruses).

It used to be thought that the longer the fluid was present, the thicker it became. Thus, the term "glue ear" became synonymous with chronic OME. It is now thought that the thickness of the fluid relates more with the particular ear than with how long the fluid is present.

Symptoms

The hallmark of OME is the lack of obvious symptoms in those who most commonly have the condition. Older children and adults often complain of muffled hearing or a sense of fullness in the ear. Younger children may turn up the television volume. Most often OME is diagnosed when someone examines the ear for another reason, such as a well-child physical.

Diagnosis

A direct inspection of the ear with an otoscope may show dullness, air bubbles, or fluid behind the eardrum. Pneumatic otoscopy reveals a decrease in the normal mobility of the eardrum. An ENT might use an otomicroscope for improved visualization.

A tympanometer is a more accurate tool for to diagnosing OME. A soft rubber probe is placed in the ear with an airtight seal. Reflected sound from the eardrum is measured as the machine varies the pressure in the ear canal, altering the stiffness of the eardrum. The results of the test suggest the amount and thickness of the fluid present.

An acoustic otoscope or reflectometer is a more portable device that dose not require an airtight seal. It accurately detects the presence of fluid in the middle ear.

An audiometer or some other type of formal hearing test may be important to help decide what treatment is warranted.

Treatment

In otherwise healthy children, the first line treatment for OME is to adjust environmental factors if possible (encourage breast-feeding, avoid cigarette smoke, reconsider group daycare). If allergies are present, avoiding the allergens can be effective (e.g., house dust). Most often the fluid will clear on its own, and suggested treatment might be either to wait and observe, or to try a single round of antibiotics.

If the fluid is still present after 6 weeks, treatment might include further observation, a hearing test, and/or a single trial of antibiotics (if not given earlier). If the fluid is still present at 12 weeks, hearing should be tested. If there is significant hearing loss (> 20 decibels), antibiotics or ear tube placement (grommets) might be appropriate.

If the fluid is still present after 4 to 6 months, tubes are probably indicated even if there is no significant hearing loss. Laser myringotomy is a newer alternative to ear tube surgery.

Sometimes adenoid removal is necessary to restore proper functioning of the eustachian tube.

Otitis media with effusion usually resolves on its own over weeks or months. Treatment may accelerate this process. As long as fluid is present in the middle ear, hearing will be impaired. This can interfere with language development in children. The disorder is usually not a threat to life but may result in serious complications. Glue ear is less likely to clear in a timely fashion than OME with a thinner effusion.

It is normal to have OME (fluid) for several weeks following treatment of an acute ear infection.

Complications

• Temporary hearing loss
• Permanent damage to the ear with partial or complete deafness
• Speech or language delay
• Cholesteatoma
• Tympanosclerosis
• Acute otitis media

Although fluid can go unnoticed, it can cause significant hearing problems in children. Any fluid that lasts longer than 8-12 weeks is cause for concern -- in children, hearing problems may cause speech to develop slowly. Permanent hearing loss is rare, but the risk increases the more ear infections a child has.

Prevention

The goals of prevention are decreasing exposure to common ear pathogens, boosting immunity, and improving the function of the eustachian tube.

To decrease exposure, smaller daycare size, especially in the winter months, can make a big difference. Daycares of six or fewer children result in measurably fewer ear infections. Frequent hand and toy washing is also helpful. Fresh air and air filters decrease exposure to airborne pathogens. Also, avoid the overuse of antibiotics. The overuse of antibiotics breeds increasingly effective disease-causing bacteria.

Breastfeeding for even a few weeks will make a child less prone to ear infections for years. The pneumococcal vaccine can prevent infections from the most common cause of acute ear infection (which leads to OME). The flu vaccine can also help.

To aid proper eustachian tube function, avoid irritants such as cigarette smoke. Avoid drinking while lying flat, and discontinue pacifier use as early as practical. Up to 40% of cases of OME have an allergic component, so identifying and avoiding allergens can be very effective prevention.

For adults and older children, chewing gum can aid eustachian tube function. Some evidence suggests that gum sweetened with xylitol may be even more effective.

References

American Academy of Family Physicians, American Academy of Otolaryngology-Head and Neck Surgery, American Academy of Pediatrics Subcommittee on Otitis Media with Effusion. Otitis media with effusion. Pediatrics. 2004 May;113(5):1412-29.