Diseases of the middle ear include perforation of the eardrum and infection. Perforation of the eardrum may be caused by injury from a sharp object, a blow to the ear, or by sudden changes in atmospheric pressure.
Infection of the middle ear, whether acute or chronic, is called otitis media. Acute otitis media with effusion includes all acute infections of the middle ear caused by pus-forming bacteria, which usually reach the middle ear by way of the eustachian tube. Bacterial infection of the mastoid process, a cone-shaped, honeycombed projection of bone behind the auricle, may occur as a complication of middle ear infections. Hearing impairment often follows because newly malformed tissues affect the mobility of the eardrum and the ossicles. Painful swelling of the eardrum may require a surgical incision to permit drainage of the middle ear. Since the use of penicillin and other antibiotics became widespread, mastoid complications have become much less frequent. Sometimes acute otitis media with effusion leads to a chronic infection that does not respond readily to antibacterial agents.
Acute and chronic nonsuppurative otitis media, which do not involve the formation or discharge of pus, are caused by closure of the eustachian tube due to conditions such as a head cold, diseased tonsils and adenoids, inflammation of the sinuses, or riding in airplanes without pressurized cabins. The chronic form can also result from bacterial infection. Because the watery discharge impairs hearing, chronic otitis media in young children may interfere with language development. A variety of treatments are employed, including use of antibiotics and antihistamines, removal of tonsils and adenoids, and insertion of tubes into the middle ear to allow drainage.
About 1 in 100 adults has hearing loss due to a condition called otosclerosis or otospongiosis, in which an abnormal amount of spongy bone is deposited between the stapes and the oval window. As a result, the stapes becomes immobilized and can no longer transmit sensations to the inner ear. If the condition progresses, surgical removal of the bony deposit is necessary, followed by reconstruction of the connection between the stapes and the oval window. Sometimes the surgeon will replace the stapes with a mechanical piston-like device. Even after successful surgery, deposits of bony tissue may again build up and cause hearing loss several years later.