Alternative Names acute otitis externa, external canal infection
Definition Inflammation or infection of the tissues of the canal that extends from the outer ear to the eardrum.
What is going on in the body? Acute otitis (oh-tie-tis) externa (ik-stir-nah) is an inflammation or infection of the outer ear, called the auricle (or-i-kal), and the external canal. The outer ear is shaped to concentrate and collect sound and direct it down toward the eardrum through the external canal. The outer ear canal contains oil, sweat and ear wax, or cerumen (sah-rew-mun) glands. Ear wax helps maintain a fairly acidic environment in the ear canal. People with diabetics who are prone to ear canal infections have an increase in the alkaline level of their ear wax, which is thought to be a cause of ear canal infections.
Otitis externa also can occur if a hair follicle (a sac in the skin from which a hair grows) in the ear canal becomes infected. This is termed folliculitis (fah-lik-yah-lie-tis). If the infected hair follicle is unable to drain, an abscess, or a pus-filled hole surrounded by swollen tissue, can form.
What are the signs and symptoms of the infection? Most people have discoloured ear drainage and intense pain. Sometimes, when a person's ear canal is full of dirt or swollen, they also cannot hear well. These symptoms are similar to those of acute otitis media but acute otitis media typically affects children younger than 6 years of age, whereas otitis externa usually does not begin until late childhood.
Acute otitis externa is very tender and painful around the opening of the ear canal and around the outer portion of the ear when touched. Sometimes the tissue in front of and below the ear can also become painful, tender and swollen. This occurs as the infection in the ear canal moves through small holes in the cartilage of the outer ear canal and then into the surrounding soft tissue.
Acute otitis externa involves extensive swelling of the outer ear canal with infected material. There also may be ear wax and shredded skin from the ear canal in the ear canal itself.
If there is an infected hair follicle, usually the only portion of the ear canal that is affected is the follicle itself. The skin around the follicle may be swollen, red, and tender. The entire ear canal is not infected.
What are the causes and risks of the infection? Acute otitis externa can be caused by:
water left in the ear, which is why it is also called swimmer's ear. The dampness plus ear wax and shed skin is a perfect breeding ground for infection.
using cotton tipped swabs
lower levels of acidity in the ear wax
very narrow openings into the ear canal or benign (non-cancerous) bone growths in the ear canal called osteomas(os-tee-oh-mas) that do not allow water to drain out effectively, thus promoting infection.
chronic irritation of the ear canal, or chronic otitis externa.
Exostoses, which are very common today since our young people have started surfing in cold water wearing wet suits. Again the narrow opening does not allow water to drain and promotes infection.
Fungal infections may also occur in the ear canal, although they are less painful. These do not respond to antibiotics and will need topical antifungals. The infected material from a fungal infection is a mix of dark grey, white and yellow pus that may have mould on its surface.
It is not know what causes the infection of hair follicles in the ear canal.
There are two main risks of acute otitis externa. These are that:
infection can spread to the facial tissues in people with reduced immunity, such as people with diabetes
infection can spread into the bone of the ear canal and the temporal bone, which is 1 of 2 bones that make up the lower part of the head There is a special risk for people with diabetes. Delayed or inappropriate treatment puts them at risk for malignant otitis externa (aggressive bacterial infection affecting the temporal bone and skull base).
What can be done to prevent the infection? Since water is the most common cause of infections, it is important to get it all water out of the outer ear canal after bathing or swimming. This can be done by dropping a mixture of peroxide and rubbing alcohol into each ear. This peroxide/alcohol mixture should not be used if there is a hole in the eardrum. Sometimes rubbing alcohol alone may work. White table vinegar can also be helpful when applied in drops because it restores an acid environment to the ear canal.
How is the infection diagnosed? Otitis externa is diagnosed by examining the outer ear canal. Cultures can be helpful if the infection is not responding to treatments.
What are the long-term effects of the infection? Frequent outer ear infections or outer ear infections that have not been completely treated can cause the skin of the ear canal to thicken. This makes the ear canal narrower. Sometimes major scarring occurs. Ear canal skin that is replaced by scar tissue can prevent sound from effectively reaching the eardrum.
What are the treatments for the infection? Otitis externa is usually treated with antibiotic- and steroid-containing ear drops such as hydrocortisone/neomycin/polymixin B. It is also very important to have the ear wax and shed skin removed. If the infection spreads into the soft tissues around the ear, oral antibiotics may be needed. If the ear canal is particularly swollen, placement of a wick to draw the ear drops in is helpful. Treatment for infected hair follicles would be very similar. Other treatments include corticosteroids and acetic acid, or vinegar therapies.
What are the side effects of the treatments? Side effects may be caused by the medication that is used. One of the most common topical antibiotic solutions contains neomycin. Some people have a neomycin skin sensitivity, which causes a reaction in the ear canal very similar to poison ivy. If the person continues to have a lot of swelling of the ear canal and itching, then the antibiotic containing neomycin needs to be stopped and other treatments that do not contain neomycin started.
What happens after treatment for the infection? Successful treatment completely heals the ear canal or hair follicles.
How is the infection monitored? The infection is mostly monitored by the severity of symptoms. If a person begins to notice early swelling, ear canal tenderness, and pain, white table vinegar irrigations or drops may keep symptoms from getting worse. If the symptoms intensify, then medical attention needs to be sought. Any spread of the infection into the soft tissues around the ear or other unusual symptoms, such as dizziness or facial weakness, are medical emergencies and require immediate attention.
Author: Mark Loury, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
