DEAFNESS ( AS. deaf, 0I1G. loop, Ger. boob, Guth. daubs, deaf ; probably originally dull of sense; ef. MHG. lump, stupid. 011G. tuna), deaf, dumb, Gk. TwO6s, typhlos, blind). Com plete or partial imperfection of hearing that nay Loth ears or one, may and may not date from birth, and may be either permanent or tem porary. Among the numerous possible causes of deafness, the following deserve mention here: (1) Wax in the ear touching the drum mem brane; (2) swelling of the lining membrane of the Eustachian tubes, the canals that lead front the upper part of the throat to the middle ear, one on each side; (3) perforation if the drum membrane; (4) middle-ear disease, (hiring which exudation accompanying inflammation colleets behind the drum membrane, or about the ossicles (the small !mints of the ea•). or during which adhesions form between the ossicles, stiffening their joints so that they cannot move freely against each other; (5) internal-ear disease, either labyrinthine trouble or affeetion of the eighth nerve; (0) diseases of the brain involving sonic of the auditory centres; (7)munips. measles, scarlet fever. and sonic other diseases, are ac companied by middle-ear disease; (8) quinine and the salicylates pause temporary deafness; (9) sudden concussion sometimes ruptures the drum of the ear. awl constant noise• like that in
a boiler-shop. injures the auditory nerve from over-excital ion.
The treatment of deafness depends of course upon its cause. Wax should be removed by syringing or curetting. Closure of the Eusta chian tubes is treated by catheterization and local applications. In eases of perforation, the drum may grow again, after the cure of middle ear disease, or may be remedied by the applica tion of a paper disk. Middle-ear diseases may be cured by treatment through the Enstaehiztn tubes, or may nevessitate the operathin of tre phining through the skull back of the external ear. The ossieles may lie removed in part, leav ing, the foot plate of the stimip-bone in position, the oval window in the labyrinth, and clearing out the remains of the drum mem brane; in which case the waves of sound strike the stirrup-plate in place of the drum membrane and are conducted to the nerve-filaments. nal-ear disease may be relieved by internal med ication. but is generally permanent. See EAR: DEAF MUTE; NERVOUS SYSTEM.