Medical expert of the article
New publications
Otosclerosis - Causes and Pathogenesis
Last reviewed: 04.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Causes of otosclerosis
The cause of otosclerosis has not been established. Among the numerous theories of the disease's origin, the influence of inflammation and infectious effects are highlighted.
Recent studies have revealed the provoking role of the measles virus in patients with a genetic predisposition to otosclerosis. Increased levels of IgG, specific for measles virus antigens, have been noted in the perilymph of patients. These antigens have also been isolated by immunohistochemical methods from an active otosclerotic lesion, but the actual significance of the virus in the development of the disease has not been established.
There is a hereditary theory of the origin of otosclerosis. Its gene has not been precisely identified, in some studies the place of its search is limited to chromosome 15q25-26, in others the occurrence of the disease is associated with the state of the COL1A1 gene, responsible for the synthesis of collagen. The participation of autoimmune processes in the occurrence of otosclerosis has been confirmed, but their significance has not been definitively determined.
Pathogenesis of otosclerosis
Histologically, an otosclerotic lesion is a section of newly formed bone with an irregular structure and numerous vascular spaces. Highly active areas are more common in otosclerosis foci in young patients. Activation of otosclerotic processes occurs under the influence of various endogenous and exogenous factors, including surgical trauma to an “immature” lesion. The number of active foci decreases with age. Otosclerosis foci can be single or multiple, limited or diffuse, and usually symmetrical. They are found in the cochlear capsule in 35%, in the semicircular canals in 15%, and in the cochlear window area in 40% of cases of “histological” otosclerosis. Massive damage to the stapes base, detected intraoperatively, occurs in 10-40% of patients. Foci are often located in the vestibular window area. Localization of the otosclerotic focus along the edge of the vestibular window with involvement of the annular ligament and the stapes crura leads to ankylosis of the latter and the development of conductive hearing loss (conductive form of otosclerosis). Formation of the otosclerotic focus in the area of the scala labyrinthine leads to the development of hearing loss with a neurosensory component (cochlear or mixed form of otosclerosis).
[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ]