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Otosclerosis
Last reviewed: 04.07.2025
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Otosclerosis (otospongiosis) is a disease of the organ of hearing caused by a focal pathological process in the bony labyrinth, often leading to fixation of the base of the stapes in the vestibular window, manifested by progressive, usually bilateral, hearing loss and tinnitus. This is a focal change in the enchondral layer of the bony capsule of the ear labyrinth.
ICD-10 code
- H80 Otosclerosis.
- H80.0 Otosclerosis involving oval window, non-obliterating.
- H80.1 Otosclerosis involving oval window, obliterating.
- H80.2 Cochlear otosclerosis.
- H80.8 Other forms of otosclerosis.
- H80.9 Otosclerosis, unspecified.
Epidemiology of otosclerosis
The prevalence of otosclerosis in the population is approximately 1%. The disease occurs in all age groups, clinical manifestations are most often detected at the age of 20-50 years. Women predominate in a ratio of 2 to 1. Low prevalence in people of African descent (0.5% of the population).
Classification of otosclerosis
According to the nature of the audiometric curve, tympanic (fenestral), cochlear (retrofenestral, intracochlear, labyrinthine) and mixed (tympanocochlear, fenestroretrofenestral) forms of otosclerosis are distinguished. The first is characterized by normal values of auditory sensitivity with bone conduction. The second audiological curve does not differ from sensorineural hearing loss. The third combines the features of the first and second.
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.
Otosclerosis - Causes and Pathogenesis
Symptoms of otosclerosis
Symptoms of otosclerosis include hearing loss and tinnitus that progress at varying rates. Periods of stabilization alternate with periods of significant hearing loss, but hearing loss, like deafness, never regresses. Rapid development of the disease, characteristic of the so-called juvenile form, in which severe hearing loss develops over a short period of time, is rarely observed. According to some authors, 70-80% of cases of the first manifestation of otosclerosis occur between the ages of 20 and 40. Hearing loss in otosclerosis is usually bilateral, and several months to years may pass between its appearance on one side and the other. A characteristic sign of otosclerosis is a relatively better perception of speech in noise conditions than in silence - paracusis willisii (Willis symptom, Willis phenomenon, paracusia).
Diagnosis of otosclerosis
Otoscopic signs of otosclerosis are extremely scarce. Characteristic symptoms are found in only 10-21% of patients. These include Lempert's symptom (thinning of the eardrum with a change in its color due to atrophy of the fibrous layer) and Schwartze's symptom (translucence of the pink-colored hyperemic mucous membrane in the promontory area through the thinned eardrum: a sign of the active stage of otosclerosis). Characteristic are the absence or decrease in the amount of sulfur (Tounbee's symptom), atrophy and dryness of the skin of the external auditory canal. With otosclerosis, a decrease in the sensitivity of the skin of the external auditory canal and eardrum, a decrease in the secretion of the sweat glands, a wide external auditory canal (Virchowsky-Tillot's symptom) are also observed.
Treatment of otosclerosis
Hearing loss due to otosclerosis is well corrected with the help of hearing aids, therefore the preliminary conversation with the patient should end with an explanation of the possibility of choosing a treatment method - surgical (with a certain probability of complications) or electroacoustic (devoid of this drawback).
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