Otosclerosis is one of many genetic and acquired conditions that affect the osseous structures. Others include tympanosclerosis, Paget disease Paget Disease of Bone Paget disease of bone is a chronic disorder of the adult skeleton in which bone turnover is accelerated in localized areas. Normal matrix is replaced with softened and enlarged bone. The disease... read more , branchio-oto-renal dysplasia, osteogenesis imperfecta Osteogenesis Imperfecta Osteogenesis imperfecta is a hereditary collagen disorder causing diffuse abnormal fragility of bone and is sometimes accompanied by sensorineural hearing loss, blue sclerae, dentinogenesis... read more , and Goldenhar syndrome.
In otosclerosis, the new bone traps and restricts the movement of the stapes, causing conductive hearing loss Pathophysiology . Otosclerosis also may cause a sensorineural hearing loss Hearing Loss Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss (1). More than 10% of people in the US have some degree of hearing loss that compromises their... read more , particularly when the foci of otosclerotic bone are adjacent to the scala media. Otosclerosis tends to run in families, and half of all cases are inherited. There is a 25% chance of developing otosclerosis if one parent has it and a 50% chance if both parents have it. Otosclerosis is a complex disease with rare autosomal dominant forms caused by a single gene. By linkage analysis, the localization of an otosclerosis gene is chromosome 15q25-q26. The measles virus plays an inciting role in patients with a genetic predisposition for otosclerosis.
Although about 10% of White adults have some otosclerosis (compared with 1% of Blacks), only about 10% of affected people develop conductive hearing loss. Hearing loss caused by otosclerosis rarely may manifest as early as age 7 or 8, but most cases do not become evident until the late adolescent or early adult years, when slowly progressive, asymmetric hearing loss is diagnosed.
A hearing aid may improve hearing. Alternatively, stapedectomy to remove some or all of the stapes and to replace it with a prosthesis may be beneficial, but the risks of hearing loss and impaired vestibular function need to be considered.