Malignant otitis externa

Definition

Malignant otitis externa is a disorder involving inflammation and damage of the bones and cartilage at the base of the skull.

Alternative Names

Osteomyelitis of the skull; Otitis externa - malignant

Causes, incidence, and risk factors

Malignant otitis externa is caused by the spread of an outer ear infection (otitis externa, also called swimmer's ear). It is an uncommon complication of both acute swimmer's ear and chronic swimmer's ear.

Risks for this condition include:

• Chemotherapy
• Diabetes
• Weakened immune system

External otitis is often caused by difficult-to-treat bacteria such as pseudomonas. The infection spreads from the floor of the ear canal to the nearby tissues and into the bones at the base of the skull. The infection and inflammation may damage or destroy the bones. The infection may spread more and affect the cranial nerves, brain, or other parts of the body.

Symptoms

• Drainage from the ear - yellow, yellow-green, foul smelling, persistent
• Ear pain - felt deep inside the ear and may get worse when moving head
• Hearing loss
• Itching of the ear or ear canal
• Fever

Signs and tests

A doctor will look into your ear for signs of an outer ear infection (otitis externa). The head around and behind the ear may be tender to touch. A nervous system (neurological) examination may show that the cranial nerves are affected.

If there is any drainage, the doctor may send it to the lab for a culture. The purpose of the culture is to look for bacteria or fungi, usually the bacteria Pseudomonas.

To look for signs of a bone infection next to the ear canal, the following tests may be performed:

• CT scan of the head
• MRI scan of the head
• Radionuclide scan

Treatment

The goal of treatment is to cure the infection. Treatment often lasts for several months, because it is difficult to treat the bacteria and reach an infection in bone tissue.

Antibiotics that are effective against the microorganism are given for long periods of time. They may be given through a vein (intravenously), or by mouth. Antibiotics should be continued until scans or other tests show that inflammation has gone down.

Occasionally, surgery to remove dead or damaged tissue (surgical debridement) in the skull is needed.

Expectations (prognosis)

Malignant otitis externa usually responds to long-term treatment, but it may return in the future.

Complications

• Damage to the cranial nerves, skull, or brain
• Return of infection, even after treatment
• Spread of infection to the brain or other parts of the body

Calling your health care provider

Call for an appointment with your health care provider if:

• You develop symptoms of malignant otitis externa
• Symptoms continue despite treatment
• You develop new symptoms

Go to the emergency room or call the local emergency number (such as 911) if you have:

• Convulsions
• Decreased consciousness
• Severe confusion

Prevention

To prevent an external ear infection:

• Dry the ear thoroughly after it gets wet.
• Avoid swimming in polluted water.
• Protect the ear canal with cotton or lamb's wool while applying hair spray or hair dye (if you are prone to getting external ear infections).
• After swimming, place 1 or 2 drops of a mixture of 50% alcohol and 50% vinegar in each ear to help dry the ear and prevent infection.

Treat acute otitis externa completely. Do not stop treatment sooner than your health care provider recommends. Following your doctor's plan completely will reduce the risk of malignant otitis externa.