deafness: Conductive Deafness
Conductive problems are those that disrupt the conduction of sound through the outer and middle ear (see ear), affecting hearing before the sound reaches the cochlea and the nerve receptors of the inner ear. Disturbances of the conductive mechanism are often temporary or curable. Most such cases are caused by otitis media, an infection that spreads to the middle ear from the upper respiratory tract; the condition usually responds to antibiotic therapy, but serious cases may require drainage of collected fluids through an incision in the eardrum (tympanum) or insertion of a tiny drainage tube. Foreign bodies or impacted wax can cause hearing loss and must be removed by a physician. In adults a predominant cause of conductive deafness is otosclerosis, a chronic hereditary condition in which spongy bone formation results in fixation of the stapes (the bone that connects the middle ear to the inner ear) and restricts its vibration. Important advances in surgical techniques have led to successful treatment of otosclerosis by replacing the stapes with a combination of grafted tissue, plastic, and wire appliances. Deafness can also be caused by perforation or rupture of the eardrum by a sudden loud noise, by physical puncture, or as a result of an infectious disease. In some such cases the eardrum can be repaired by grafting. Today there are many advanced medical techniques for treating infection of the mastoid and congenital malformations of the outer and middle ear that, if neglected, might result in deafness.
- Conductive Deafness
- Sensorineural Deafness
- Mechanical and Educational Aids
- History of Education for the Deaf
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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