Definition Necrotising external otitis is a serious ear infection that can destroy the skin of the ear canal and progress to involve the bones of the skull.
What is going on in the body? The infection begins in the external ear canal. The bacteria causing the infection often invade through the skin lining the ear canal and then into the ear canal itself. Left untreated, it can spread rapidly into the skull bones and damage them.
A skull bone called the temporal bone, which is most commonly affected by severe infections, is in contact with several important structures. These include the nerves that control the face muscles and the main blood vessels that lead to and from the brain. Infection of these and other structures can cause permanent damage or even death.
What are the signs and symptoms of the infection? The first signs of infection are:
pain in the opening to the ear canal and ear flap
drainage of pus from the ear canal
low-grade fever
As the infection spreads into the bone, symptoms can include:
severe pain
thickening and swelling of the skin covering the temporal bone
high fever
a lot of swelling and infected material in the external canal
swelling of the skin around the ear
If the infection affects the nerves for movement of the face, facial paralysis or weakness may occur. Should the infection spread to the inner ear, hearing loss and dizziness may result. The infection can even spread to the brain, which may lead to meningitis. This is an infection of the membrane covering the brain and spinal cord. The brain material itself may also become infected.
What are the causes and risks of the infection? This disease often occurs in people who have problems with their immune system. This includes people with diabetes, AIDS, and cancer. People who take medications to suppress the immune system are also at an increased risk of getting this infection.
The primary risks of this condition are permanent damage to important structures near the ear, and even death.
What can be done to prevent the infection? The best way to prevent this condition is with early treatment for any outer ear infection. This can keep it from spreading. People with diabetes should maintain good control of their blood sugar to reduce the risk of this infection.
How is the infection diagnosed? A doctor can often diagnose this condition by examining the ear and taking a medical history. Other tests that may need to be done include:
blood tests.
special x-ray tests, such as a CAT scan.
cultures of the ear canal. This involves sending a swab from the ear canal to a laboratory to see which bacteria are causing the infection.
What are the long-term effects of the infection? Usually, there are no long-term effects. However, if left untreated or if the person does not respond to therapy, long-term effects may occur. The infection may permanently damage the ear, skull, nearby nerves and blood vessels, and even the brain. Death is possible with severe infections.
What are the risks to others? This condition generally poses no risk to others.
What are the treatments for the infection? When the infection is found early enough, only antibiotics are needed. The underlying immune system problem needs to be corrected quickly if possible. Hyperbaric oxygen therapy, or giving oxygen at a high pressure, often helps to get rid of the infection. If antibiotics and hyperbaric oxygen therapy do not work, then surgery is needed.
What are the side effects of the treatments? All medications have possible side effects. Antibiotics may cause allergic reactions or stomach upset. Specific side effects depend on the drugs used.
There are usually no side effects with hyperbaric oxygen therapy. However, special tubes may need to be placed into the eardrums during this procedure.
There is always some risk with surgery. In this case, surgery could result in facial paralysis, dizziness, hearing loss and taste disturbance.
What happens after treatment for the infection? If treatment is successful, the infection is stopped and the symptoms resolve. The tissue can then heal.
How is the infection monitored? If an outer ear infection gets worse and the symptoms do not go away, medical attention is needed. Repeat examinations of the ear may be done until the condition has resolved. Blood and x-ray tests may be used for monitoring in some cases.
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
