Otosclerosis

A disorder of the middle ear that causes progressive deafness. The condition usually develops in both ears. Otosclerosis occurs when overgrowth of bone immobilizes the stapes (the innermost one of the three tiny bones in the middle ear). As a result, sound vibrations are prevented from passing along the bone to the inner ear. To an affected person, sounds are muffled but can be distinguished more easily if there is background noise. Otosclerosis frequently runs in families, and symptoms usually start to appear in early adulthood. The condition affects more women than men, and often develops during pregnancy. Hearing loss progresses slowly over 10 to 15 years and is often accompanied by tinnitus and, more rarely, vertigo. A degree of sensorineural deafness may develop, making high tones difficult to hear and causing the sufferer to speak loudly. The condition is diagnosed by hearing tests. It can be cured by stapedectomy, a surgical procedure in which the stapes is replaced by a tiny piston, which moves through a hole created in the inner ear. Because the piston can move freely, it can transmit sound vibrations to the inner ear. Alternatively, a hearingaid can markedly improve hearing.