Alternative names
Osteomyelitis of the skull; Malignant otitis externa

Definition

Malignant otitis externa is a disorder involving inflammation and damage of the bones and cartilage of the base of the skull. It is caused by the spread of infection from an external ear infection (otitis externa).

 
• Malignant = harmful and invasive  
• otitis = ear infection and inflammation  
• externa = outer

Causes, incidence, and risk factors
Otitis externa, also called swimmer’s ear, is an ear infection that occurs in the outer ear. Malignant otitis externa is an uncommon complication of both acute otitis externa and chronic otitis externa. Diabetics and people whose immune systems are compromised from diseases or medications are particularly susceptible to malignant otitis externa.

The infection of external otitis, often caused by difficult-to-treat bacteria such as Pseudomonas, spreads from the floor of the ear canal to the adjacent tissues and into the bones of the base of the skull. The bones may be damaged or destroyed from the resulting infection and inflammation. The infection may further spread and affect the cranial nerves, the brain, or other parts of the body.

Symptoms

 
• drainage from the ear       o yellow, yellow-green, pus, foul smelling       o persistent  
• hearing loss  
• ear pain       o may worsen on head movement       o may be located deep within the ear  
• 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 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 to be performed. The purpose of the culture is to look for bacteria or fungus, usually the bacteria Pseudomonas.

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

 
• CT scan of the head  
• X-rays of the skull  
• MRI scan of the head  
• Radionuclide scan

Treatment
The goal of treatment is to cure the infection. Treatment is often prolonged, lasting several months, because of the difficulty of treating the bacteria and the difficulties reaching an infection that is within bone tissue.

Antibiotics effective against the microorganism are given for prolonged periods. They may be given intravenously, or sometimes by mouth. Antibiotics should be continued until scans or other tests show a reduction in inflammation.

Occasionally, surgical debridement of the skull is needed to allow drainage and to reduce deterioration of the bone.

Expectations (prognosis)
Malignant otitis externa usually responds to prolonged treatment but may return in the future.

Complications

 
• damage to the cranial nerves, skull, or brain  
• spread of infection to the brain or other parts of the body  
• malignant otitis externa returning in the future, even after treatment

Calling your health care provider

Call for an appointment with your health care provider if:

 
• symptoms of malignant otitis externa develop  
• symptoms persist despite treatment  
• new symptoms develop

Go to the emergency room or call the local emergency number (such as 911) if Convulsions, decreased consciousness, severe confusion, or similar symptoms develop.

Prevention

To prevent an external ear infection, dry the ear thoroughly after exposure to moisture. Avoid swimming in polluted water and protect the ear canal with cotton or lamb’s wool while applying hair spray or hair dye (if susceptible to external ear infections).

Treat acute otitis externa completely and do not stop treatment sooner than recommended by your health care provider. Following your doctor’s plan completely will reduce the risk of it becoming malignant otitis externa.

After swimming, 1 or 2 drops of a mixture of 50% alcohol and 50% vinegar in each ear will help to dry the ear and prevent infection.

Medical Encyclopedia

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.