Mastoiditis is an infection that affects the mastoid bone.

The mastoid bone is a part of the skull behind the ear which has small air cells or sinuses that connect to the middle ear. Mastoiditis is an infection that affects the mastoid bone. The infection typically starts first in the middle ear and spreads into the mastoid. Infection in the mastoid may destroy the thin bone of the air cells. Progressive infection trapped in the mastoid, mastoiditis, may cause serious complications.

Early symptoms of mastoiditis include ear pain and pressure, drainage of pus from the ear, and hearing loss. As acute mastoiditis worsens, the pus becomes creamy, pain waxes and wanes through the day, and swelling behind the ear may appear. Fever is variable, commonly worse as the pain and pressure increase.

Meningitis, brain spinal-fluid infection, or brain abscess may complicate unmanaged mastoiditis. Since the facial nerve runs through the mastoid, facial paralysis sometimes occurs on the affected side. Permanently impaired hearing, eardrum membrane perforation, and cholesteatoma may also develop as a result of chronic mastoiditis. After an ear examination by the physician, a CAT scan reveals whether the mastoid infection is likely to respond to antibiotics alone or antibiotics plus surgery.

When possible, an audiogram documents the degree of associated hearing loss. The evaluation may happen in the emergency room or the physician’s office depending on how acutely ill the person is. Less severe acute mastoiditis typically resolves with oral antibiotics. More severe acute mastoiditis, especially if associated with complications, may require intravenous antibiotics.

When the air cell bony walls have been destroyed by progressive infection, when swelling behind the ear develops, or other serious complications arise, surgery is usually necessary. Persisting infection that fails to respond to antibiotics may require surgery, as well. Surgery to clean out mastoid infection is called a mastoidectomy. When an eardrum (tympanic membrane) hole is also present, it may be repaired simultaneously with a tympanoplasty.

In the developed world, other serious complications of mastoiditis are rare. Life threatening problems include obstruction of a major vein from the brain, the sigmoid sinus. Sigmoid sinus occlusion causes severe fevers and headache, commonly in association with meningitis.

Mastoid infection may spread into the neck causing marked swelling on the side of the neck along with fever and exquisite tenderness. Infection in the neck left untreated can impair breathing and spread into the chest. In areas of the world where tuberculosis is common, tuberculous mastoiditis may occur as well. Rarely, tumors and disorders of the blood cell system or immune system may also look like mastoiditis.