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Mastoiditis is an infection of the spaces within the mastoid bone. It is almost always associated with otitis media, an infection of the middle ear. In the most serious cases, the bone itself becomes infected.


The mastoid is a part of the side (temporal bone) of the skull. It can be felt as a bony bump just behind and slightly above the level of the earlobe. The mastoid has been described as resembling a "honeycomb" of tiny partitioned-off airspaces. The mastoid is connected with the middle ear, so that when there is a collection of fluid in the middle ear, there is usually also a slight collection of fluid within the airspaces of the mastoid.
Mastoiditis can range from a simple case of some fluid escaping into the mastoid air cells during a middle ear infection, to a more complex infection which penetrates through to the lining of the mastoid bone, to a very severe and destructive infection of the mastoid bone itself.

Causes and symptoms

Mastoiditis is caused by the same types of bacteria which cause middle ear infections (Streptococcus pneumoniae and Haemophilus influenzae), as well as by a variety of other bacteria (Staphylococcus aureus, Pseuodomonas aeruginosa, Klebsiella, Escherichia coli, Proteus, Prevotella, Fusobacterium, Porphyromonas, and Bacteroides). Mastoiditis may occur due to the progression of an untreated, or undertreated, middle ear infection.
Symptoms of mastoiditis may at first be the same as symptoms of an early middle ear infection. With progression, however, the swollen mastoid may push the outer ear slightly forward and away from the head. The area behind the ear will appear red and swollen, and will be very sore. There may be drainage of pus from the infected ear. In some cases, the skin over the mastoid may develop an opening through which pus drains. Fever is common.


Mastoiditis is usually suspected when a severe middle ear infection is accompanied by redness, swelling, and pain in the mastoid area. A computed tomography scan (CT scan) will show inflammation and fluid within the airspaces of the mastoid, as well as the erosion of the little walls of bone that should separate the air spaces. If there is any fluid draining from the ear or mastoid, this can be collected and processed in a laboratory to allow identification of the causative organism. If there is no fluid available, a tiny needle can be used to obtain a sample of the fluid which has accumulated behind the eardrum.


Identification of the causative organism guides the practitioner's choice of antibiotic. Depending on the severity of the infection, the antibiotic can be given initially through a needle in the vein (intravenously or IV), and then (as the patient improves) by mouth.
In the case of a very severe infection of the mastoid bone itself, with a collection of pus (abscess), an operation to remove the mastoid part of the temporal bone is often necessary (mastoidectomy).

Key terms

Abscess — A pocket of infection, usually including a collection of pus.
Meningitis — Inflammation and infection of the tissues covering the brain and spinal cord (the meninges).
Otitis or oteitis — An infection of the middle ear; marked by an enlargement of bone, tenderness and dull aching pain.


With early identification of mastoiditis, the prognosis is very good. When symptoms are not caught early enough, however, a number of complications can occur. These include an infection of the tissues covering the brain and spinal cord (meningitis), a pocket of infection within the brain (abscess), or an abscess within the muscles of the neck. All of these complications have potentially more serious prognoses.


Prevention of mastoiditis involves careful and complete treatment of any middle ear infections.



American Academy of Otolaryngology-Head and Neck Surgery, Inc. One Prince St., Alexandria VA 22314-3357. (703) 836-4444.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


inflammation of the mastoid antrum and mastoid cells, usually the result of an infection of the middle ear, with which the mastoid cells communicate. It most often follows sore throat and respiratory infection but can also be caused by diseases such as diphtheria, measles, and scarlet fever. Symptoms include earache and a ringing in the ears. The mastoid process may become painful and swollen. Treatment formerly was limited to mastoidectomy, in which infected cells were removed surgically. Today, however, use of antibiotics has made it possible to check most cases at an early stage, so that surgery can be avoided.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Infection in the air cell system of the mastoid process.
Synonym(s): mastoid empyema
Farlex Partner Medical Dictionary © Farlex 2012


Inflammation of the mastoid process and mastoid cells.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Inflammation of the mastoid, often secondary to middle ear infection (acute otitis media).
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


ENT Inflammation of the mastoid, often 2º to middle ear infection–acute otitis media. See Mastoid.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


Inflammation of any part of the mastoid process.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Inflammation of the mastoid air cells from infection usually spread from an OTITIS MEDIA. This is potentially dangerous as the infection may proceed through the bone into the interior of the skull and cause a brain abscess.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
The results of clinical and temporal CT show that Luc's abscess with concomitant mastoiditis has been reported in 3 cases of acute otitis media [3, 7, 8].
Mastoiditis and gradenigo's syndrome with anaerobic bacteria.
This could be a rare effect of the disease possibly caused by damage to auditory pathways due to the septic emboli in the brain or by expansion of the mastoiditis resulting in damage of the inner ear.
Thyroid stimulating immunoglobulin (TSI), ordered as a send-out lab during the patient's previous admission for mastoiditis, returned positive, and the diagnosis of Grave's disease was made.
Detailed ear, nose and throat examination should be performed to detect mastoiditis. It is recommended that genetic risk factors should be investigated, because hereditary thrombophilis factors may have a role in children.
Diagnosis can be difficult as these lesions mimic other common conditions seen by the otolaryngologist, including otitis externa, acute mastoiditis, and gingivitis.
This is called mastoiditis. Very rarely, the infection spreads deeper into the inner ear, brain or other nearby tissues.
Temporal bone computed tomography (CT) examination findings were consistent with mastoiditis on the right side.
In addition, he did this while afflicted with mastoiditis (an infection that extends to the air cells of the skull behind the ear) throughout his career.