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Inflammation of the mastoid process, a bony projection just behind the ear, almost always due to otitis media. It may spread into small cavities in the bone, blocking their drainage. Very severe cases infect the whole middle ear cleft. It causes pain behind the ear and on the side of the head. Temperature and pulse rate may rise. Tissues over the bone may swell until an abscess develops, indicating destruction of the bone's outer layer. Complications of inward spread include abscess inside the skull, thrombosis, and inner-ear infection; meningitis is a serious danger. Now rare with treatment of otitis media, mastoiditis usually responds to early antibiotic treatment; if not, surgical drainage with removal of all diseased bone is necessary.
This entry comes from Encyclopædia Britannica Concise. For the full entry on mastoiditis, visit Britannica.com.