Definition

Malignant otitis externa is a disorder that involves infection and damage of the bones of the ear canal and at the base of the skull.

Alternative Names

Osteomyelitis of the skull; Otitis externa - malignant; Skull-base osteomyelitis; Necrotizing external otitis

Causes

Malignant otitis externa is caused by the spread of an outer ear infection (otitis externa), also called swimmer's ear. It is not common.

Risks for this condition include:

• Chemotherapy
• Diabetes
• Weakened immune system

External otitis is often caused by bacteria that are hard to treat, 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 swelling may damage or destroy the bones. The infection may affect the cranial nerves, brain, or other parts of the body if it continues to spread.

Symptoms

Symptoms include:

• Ongoing drainage from the ear that is yellow or green and smells bad.
• Ear pain deep inside the ear. The pain may get worse when you move your head.
• Hearing loss.
• Itching of the ear or ear canal.
• Fever.
• Trouble swallowing.
• Weakness in the muscles of the face.

Exams and Tests

Your health care provider will look into your ear for signs of an outer ear infection. The head around and behind the ear may be tender to touch. A nervous system (neurological) exam may show that the cranial nerves are affected.

If there is any drainage, the provider may send a sample of it to the lab. The lab will culture the sample to try to find the cause of the infection.

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

• 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.

You will need to take antibiotic medicines for a long period of time. The medicines may be given through a vein (intravenously), or by mouth. Antibiotics should be continued until scans or other tests show the inflammation has gone down.

Dead or infected tissue may need to be removed from the ear canal, using a procedure called debridement. In some cases, surgery may be needed to remove dead or damaged tissue in the skull.

Outlook (Prognosis)

Malignant otitis externa most often responds to long-term treatment, especially if treated early. It may return in the future. Severe cases may be deadly.

Possible Complications

Complications may include:

• 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

When to Contact a Medical Professional

Contact your 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
• Facial weakness, loss of voice, or difficulty swallowing associated with ear pain or drainage

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.
• Maintain good glucose control if you have diabetes.
  

Treat acute otitis externa completely. Do not stop treatment sooner than your provider recommends. Following your provider's plan and finishing treatment will lower your risk of malignant otitis externa.

References

Araos R, D'Agata E. Pseudomonas aeruginosa and other pseudomonas species. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 219.

Matlock AG, Pfaff JA. Otolaryngology. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 58.