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

• Malignant = harmful and invasive
• Otitis = ear infection and inflammation
• Externa = outer

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

Persons with diabetes and weakened immune systems are particularly susceptible to malignant otitis externa.

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 adjacent tissues and into the bones at the base of the skull. The bones may be damaged or destroyed by the resulting infection and inflammation. The infection may further spread and affect the cranial nerves, the brain, or other parts of the body.

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

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