Mastoiditis is an uncommon bacterial infection of the mastoid bone behind the ear. It is usually seen in children, although adults can sometimes be affected.

The mastoid bone has a honeycomb-like structure – it contains air spaces called mastoid cells, which help maintain the air space in the middle ear (see picture, left).

Mastoiditis can develop when the mastoid cells become infected or inflamed, often as a result of a persistent middle ear infection. This can cause the porous bone to break down.

What are the symptoms?

Mastoiditis typically causes:

• fever, irritability and tiredness
• swelling behind the ear, pushing it forward 
• redness and tenderness or pain behind the ear
• a creamy discharge from the ear 
• headache
• hearing loss

When to call your GP

Call your GP if you or your child:

• have any of the above symptoms of mastoiditis
• have an ear infection that doesn’t clear up with treatment or is followed by new symptoms
• have been diagnosed with mastoiditis and treatment is not clearing it

What are the causes?

Mastoiditis sometimes develops after a middle ear infection. Bacteria from the middle ear can travel into the air cells of the mastoid bone.

Another possible cause of mastoiditis is a cholesteatoma (an abnormal collection of skin cells inside your ear), which may prevent the ear draining properly and lead to infection.

How is it diagnosed?

Your GP will want to examine the inside of your ear with an otoscope (an instrument with a light and magnifying glass), to see if any infection or cholesteatoma is present.

Most ear infections are due to a middle ear infection (otitis media). If your GP suspects you have mastoiditis as a complication of a middle ear infection, they will refer you to hospital to see an ear, nose and throat (ENT) specialist. Here you will have a further examination and tests – usually a blood test and an ear culture (testing the ear discharge for a bacterial infection).

Some children may need a CT scan, which uses X-rays and a computer to create detailed images of the inside of the skull.

How is it treated?

Mastoiditis is treated with antibiotics.

You may need to go to hospital to be treated by an ENT specialist. Antibiotics are given to you via a drip, and you may need surgery to drain the ear and to have the infected mastoid bone removed.

You could be in hospital for a few days for this treatment, until the surgeons are happy the infection is under control.

Surgery

Surgery to drain fluid from the ear is known as a myringotomy.

The doctor will make a small hole in your eardrum to drain the fluid and relieve pressure from deep inside your ear. A small tube may be inserted into the middle ear to provide ventilation and prevent fluid getting inside it. This tube will typically fall out after 6-12 months.

An operation to remove the infected mastoid bone is known as a cortical mastoidectomy – this is only usually needed if the infection is severe.

Caring for your ear after surgery

If you’ve had surgery, you’ll need to stay in hospital for a few days after the operation, and will probably need to take one or two weeks off work. Your doctor will advise you on this.

Take care not to get your operated ear wet. You should be able to wash your hair after a week, providing you do not get water inside your affected ear.

You should be able to go swimming about four to six weeks after the operation, depending on how well it has healed. Your doctor should be able to advise you at your follow-up appointment.

Outlook

With early antibiotic treatment, most people recover quickly with no complications.

However, treatment is not always easy and the condition may come back.

If a severely infected bone is not removed, it can cause hearing loss and life-threatening health complications such as a blood clot, meningitis, or a brain abscess.