What is Malignant Otitis Externa (MEO)?

A woman laying in bed with her hand over her ear

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Malignant otitis externa (MEO) is a rare complication of swimmer's ear (otitis externa). It occurs when an outer ear infection spreads to nearby tissue and bone. Despite the name, the term "malignant" does not mean you have cancer. The term "malignant" was originally used by the doctor who discovered MEO due to the serious nature of the disease and its rapid progression.

With the advent of antibiotics, outcomes for malignant otitis externa are much better than they used to be and the name is a bit misleading as to the severity of the disease. This condition is also sometimes referred to as necrotizing (malignant) external otitis.

The most common strain of bacteria responsible for malignant otitis externa is pseudomonas aeruginosa.

Risk Factors for MEO

Malignant otitis externa occurs when swimmer's ear spreads beyond the ear canal and causes a tissue or bone infection of the skull, including the temporal bone. Several factors could cause this to happen including:

  • Untreated swimmer's ear or waiting too long to seek treatment.
  • Infection caused by a resistant type of bacteria.
  • A compromised immune system from AIDS, chemotherapy, diabetes, or other conditions.

Other significant risk factors for acquiring malignant otitis externa include:

  • Living in a warm humid climate
  • Elderly
  • Male
  • Diabetic
  • Often starts out as some kind of trauma (injury) to the external ear canal

Once the infection spreads beyond the external ear canal it typically causes a bone infection at the base of the skull, specifically the temporal bone. Further progression can lead to damage to the cranial nerves and facial nerve paralysis.

Symptoms of MEO

Symptoms of malignant otitis externa will vary between individuals based on circumstances and the progression of the infection. Symptoms may include:

  • Severe ear pain that gets worse at night
  • Pain when the area behind your ear is touched
  • Ear drainage which may contain pus, be yellow or green in color or smell foul
  • Hearing loss
  • A feeling of fullness in the ear
  • Itchy ears
  • Fever (rare)
  • Difficulty swallowing
  • Facial weakness
  • Voice loss
  • Headaches

Diagnosis of MEO

Malignant otitis externa is best diagnosed by a physician who specializes in disorders of the ear, nose, and throat (called an otolaryngologist), although it can be diagnosed by physicians in other specialties.

Your doctor will consider your health history including any risk factors you may have as well as your symptoms. Your doctor will try to examine your ear with an otoscope, however, this may be painful depending on the extent and progression of the infection. They will also examine your head for tenderness.

In addition to the physical exam, certain medical tests can be used to confirm a diagnosis of MEO. Your doctor may order some of the following tests depending on their preference and your individual circumstances.

  • Blood tests including erythrocyte sedimentation rate (ESR), white and red blood cell counts, glucose and creatine levels
  • Culture of ear drainage
  • Radiographic imaging such as a CT scan to look for osteomyelitis (bone infection)
  • Biopsy of the tissue in the external ear canal

Treatment of MEO

A long course (months) of antibiotics is usually necessary to treat malignant otitis externa since bone infections are particularly hard to cure. Your doctor should wait until a culture of your ear drainage can confirm the type of bacteria causing your infection. Cultures will also give your doctor information on which antibiotics will best treat your infection.

You will need to be monitored during this time and continue antibiotics until imaging procedures no longer show inflammation. In severe cases, surgery may be required to remove the damaged bone.

Other things to be aware of:

  • Hyperbaric oxygen therapy is sometimes used in conjunction with antibiotic therapy to facilitate the healing of damaged tissues.
  • If you have diabetes, you will need to maintain tight control of your blood sugar since elevated blood sugar levels aid the growth of bacteria.

Can MEO Be Prevented?

The following tips can help to prevent malignant otitis externa:

  • If you have symptoms of swimmer's ear have it treated appropriately as soon as possible.
  • Avoid cleaning your ears with cotton swabs or sticking any objects into your ear that can cause injury.
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