Definition of Mastoiditis:

Mastoiditis is an infection of the mastoid bone of the skull. The mastoid is located just behind the outside ear.

Causes, incidence, and risk factors:

Mastoiditis is usually caused by a middle ear infection (acute otitis media). The infection may spread from the ear to the mastoid bone of the skull. The mastoid bone fills with infected materials and its honeycomb-like structure may deteriorate.

Mastoiditis usually affects children. Before antibiotics, mastoiditis was one of the leading causes of death in children. Now it is a relatively uncommon and much less dangerous condition.