otosclerosis /ō′tōsklərō″sis/ [Gk, ous + skleros, hard, osis, condition] , a hereditary condition of unknown cause in which irregular ossification occurs in the ossicles of the middle ear, especially of the stapes, causing hearing loss. It is usually first noticed between 11 and 30 years of age. Women are affected twice as often as men. The condition may worsen during pregnancy. Stapedectomy or stapedotomy is usually successful in restoring hearing.
