Mastoiditis is a bacterial infection of a skull bone located behind the ear known as the mastoid bone, states WebMD. The infection is usually triggered by inflammation from a middle ear infection. Mastoiditis causes the same symptoms in children and adults but affects the latter group less often.
A middle ear infection can cause bacteria to reach mastoid cells, or a skin cyst may prevent healthy fluid drainage from the ear, according to WebMD. The infection may continue to spread from the mastoid bone to surrounding tissue, increasing the risk of complications such as hearing loss and meningitis. In most cases, mastoiditis causes a swollen ear lobe and tenderness or redness behind the ear. The individual may experience fever and irritability or notice drooping, bulging or drainage in the ear.
Doctors initially exam the ear and head for signs of the infection, but they may need more conclusive tests, such as a CT scan or white blood cell count, to make a diagnosis, notes Healthline. Antibiotics are used to treat the infection, and patients may be instructed to take medication on their own for several days until the condition completely clears up. In severe cases, a surgeon may drain the middle ear of infectious fluid and cut out a section of the mastoid bone to enable further drainage.