How Common Is Otosclerosis? Statistics and Risk Factors

Otosclerosis affects roughly 0.3 to 0.4 percent of the general population in its clinically noticeable form, making it one of the more common causes of acquired hearing loss in young and middle-aged adults. But the condition’s true frequency is higher than diagnosis rates suggest, and who develops it depends on a tangle of genetics, sex, geography, and possibly even childhood vaccination history. The gap between how many people carry otosclerotic bone changes and how many actually lose hearing because of them turns out to be surprisingly wide.

The Gap Between Histological and Clinical Otosclerosis

One of the most striking things about otosclerosis is how many people have it without knowing. Temporal bone studies performed at autopsy have found microscopic foci of otosclerotic bone remodeling in roughly 2.5 percent of specimens, sometimes higher depending on the population studied. Yet only a fraction of those people ever developed hearing loss during their lifetimes. The clinical form, where abnormal bone growth around the stapes footplate or cochlea actually interferes with hearing, shows up in about 0.3 to 0.4 percent of the population. That means most otosclerotic foci sit quietly in the bone and never cause symptoms.

This distinction matters because it shapes how researchers talk about prevalence. A study looking at temporal bones will report one number; a study looking at diagnosed patients in a clinic will report a much smaller one. An urban population study in the Bronx, for example, found an overall diagnosed prevalence of about 20 per 100,000 patients.¹ That is 0.02 percent, which is lower than the commonly cited 0.3 percent figure, likely because it reflects only people who sought care and received a formal diagnosis. Many individuals with mild conductive hearing loss never get evaluated, and otosclerosis can progress slowly enough that people adapt without realizing something treatable is happening.

Who Gets Otosclerosis

Otosclerosis has long been described as a disease that favors certain demographics. Women are affected more often than men. In a study of untreated otosclerosis patients, about 62 percent were women.² The typical age of onset falls between the second and fourth decades of life, so most people first notice hearing changes in their twenties or thirties.³ Pregnancy has traditionally been cited as a trigger for worsening, though the mechanism behind that link is still debated.

The ethnic distribution of otosclerosis has been described differently depending on the study. Historically, textbooks stated that otosclerosis was most common in white populations and rare in people of African and Asian descent. Newer data complicates that picture. A population-based study spanning 70 years in Olmsted County, Minnesota found that between 2000 and 2017, incidence rates were actually quite similar across racial groups: about 5.2 per 100,000 person-years in whites, 6.1 in Black individuals, 5.1 in Asian individuals, and 6.1 among those of Hispanic origin.⁴ Those numbers are strikingly close to each other, which challenges the longstanding assumption that otosclerosis overwhelmingly targets white populations.

Meanwhile, the Bronx urban population study found a different pattern. Among diagnosed cases, crude prevalence was highest in Hispanics at about 43 per 100,000, followed by Caucasians at roughly 13 per 100,000, and African Americans at about 3 per 100,000.¹ The Hispanic patients in that study were predominantly foreign-born, and foreign-born Hispanics had nearly four times the odds of being diagnosed compared with U.S.-born Hispanics. That finding suggests that access to healthcare, referral patterns, and the population makeup of a given clinic can heavily influence the apparent ethnic distribution. It also raises the possibility that otosclerosis has been underdiagnosed in non-white populations for decades, which would mean the old textbook claim about racial rarity was partly an artifact of who got evaluated.

Genetic Risk Factors

Genetics plays a clear role in otosclerosis, but the inheritance pattern is messy. The condition is generally considered autosomal dominant with reduced penetrance, meaning you can carry the gene variant and never develop clinical disease. About 40 to 50 percent of all clinical cases are sporadic, with no family history at all.⁵ In the other half, a positive family history is present, and roughly 50 percent of individuals with untreated otosclerosis report known hereditary factors.²

Researchers have identified at least seven genetic loci linked to monogenic (single-gene) forms of otosclerosis, though the actual disease-causing genes at those loci have not been pinned down.⁶ More broadly, otosclerosis is treated as a complex genetic disease where multiple genes contribute small effects. One gene that has attracted particular attention is COL1A1, which codes for a major component of type I collagen, the protein that gives bone much of its structural framework. Variants in the regulatory regions of COL1A1 have been linked to otosclerosis susceptibility in Caucasian populations.⁷ A separate study in Turkish patients also found that a COL1A1 polymorphism leading to excess type I collagen production could play a role in the disease.⁸

A large genome-wide study using population biobanks identified 27 loci associated with otosclerosis and found overlap between otosclerosis risk genes and genes involved in skeletal structure more broadly.⁹ That overlap makes biological sense: otosclerosis is fundamentally a problem of abnormal bone remodeling in the otic capsule, so genes that regulate bone growth and turnover elsewhere in the body are plausible candidates. The same study noted a signal in COL4A2 (a collagen IV gene) rather than a strong direct hit on COL1A1 itself, illustrating how the genetic landscape keeps shifting as larger datasets become available.

The Measles Virus Question

For decades, researchers debated whether persistent measles virus infection in the temporal bone helps trigger otosclerosis. The idea gained traction when several groups detected measles virus genetic material in otosclerotic stapes samples removed during surgery. A review of the literature concluded that the majority of studies did support the presence of measles virus components in otosclerotic bone and a possible role in setting off the disease process, especially when combined with genetic susceptibility and autoimmune factors.¹⁰

But this remains genuinely controversial. A study of otosclerosis patients in Japan found no evidence of measles virus infection in any bone samples, primary cell cultures, or virus-susceptible cell lines tested.¹¹ A larger study of 93 patients also failed to detect measles virus RNA in any stapes sample using sensitive molecular techniques, and found that the measles virus receptor CD46 was negative in nearly all samples.¹²

What makes this debate interesting beyond the lab is the real-world pattern: the incidence of otosclerosis has been declining in many countries over roughly the same period that measles vaccination became widespread. If measles virus does contribute, then mass vaccination programs may have inadvertently reduced otosclerosis rates. Whether that is a coincidence or a causal connection remains unresolved. Researchers on both sides acknowledge that even if the virus plays a role, it is not acting alone. Genetic vulnerability seems to be a prerequisite, and the disease can clearly develop in people with no evidence of measles exposure.

Is Otosclerosis Becoming Less Common?

Multiple lines of evidence suggest that otosclerosis incidence has declined over the past several decades in Western countries. The Olmsted County study that tracked cases over 70 years documented a falling incidence rate over time.⁴ Surgical volume has also dropped. Applying recently described incidence rates to the U.S. population, one estimate put the upper bound at roughly 6,500 new cases of stapes surgery performed annually across the country.¹³ With around 1,400 otolaryngology residents in training nationally, that works out to an average of fewer than eight stapedectomy cases over an entire residency. The practical consequence is that fewer surgeons are getting the hands-on training needed to develop expertise with the procedure, which creates a feedback loop: as the disease becomes rarer, the surgical skill to treat it also becomes rarer.

The reasons for this decline are debated. Measles vaccination is one candidate explanation, as noted above. Improved nutrition, changes in fluoride exposure, and possibly shifts in other environmental factors have also been proposed. One older study found that patients drinking fluoridated water had slower hearing deterioration in their non-operated ears over a nearly 10-year follow-up, suggesting some protective effect of fluoride on otosclerotic progression.¹⁴ However, another study in the same population found that the prevalence of clinical otosclerosis was essentially the same (about 0.3 percent) regardless of whether people drank fluoridated or non-fluoridated water, suggesting fluoride may slow progression without preventing the disease from developing in the first place.¹⁵

How Otosclerosis Presents

The most familiar form involves abnormal bone growth around the stapes footplate, which fixes the stapes in place and prevents it from vibrating freely. This causes conductive hearing loss, the kind where sound is physically blocked from reaching the inner ear. But otosclerosis can also involve the cochlea itself. Cochlear otosclerosis is defined as otosclerotic involvement of the otic capsule around the cochlea, which damages the inner ear directly and causes sensorineural hearing loss or a mix of both types.¹⁶ The cochlear form is harder to diagnose and harder to treat surgically, since stapes surgery addresses the conductive component but cannot reverse inner ear damage.

In people with bilateral disease, the bone changes tend to follow a similar pattern in both ears about two-thirds of the time.¹⁷ However, unilateral hearing loss is actually more common at the time of diagnosis; in the untreated patient study mentioned earlier, bilateral hearing loss was present in only about a quarter to a third of cases depending on sex.² Tinnitus is extremely common alongside the hearing loss, reported by about 72 percent of untreated patients, which is far higher than in the general population.

Otosclerosis in Children and Teenagers

Otosclerosis is overwhelmingly an adult diagnosis, but it can appear in childhood. Juvenile otosclerosis is uncommon and often difficult to recognize because progressive conductive hearing loss in a child usually prompts clinicians to think first of middle ear infections, congenital ossicular malformations, or cholesteatoma rather than otosclerosis.¹⁸ Distinguishing otosclerosis from congenital stapes fixation is particularly important because the two conditions call for different management approaches.

A systematic review of pediatric otosclerosis cases found that among studies reporting specific ages, the mean age at surgery ranged from 10 to about 16 years, with the youngest patient being under 7.¹⁹ Case reports have described signs of the disease in children younger than 6.²⁰ These cases tend to be recognized later than they should be, partly because clinicians do not expect the diagnosis and partly because children are less able to articulate what is happening to their hearing. When a child shows progressive conductive hearing loss that does not respond to standard middle-ear treatments, otosclerosis should be on the list.

Conditions That Can Look Like Otosclerosis

One of the diagnostic challenges is that otosclerosis can resemble other bone disorders on imaging. Osteogenesis imperfecta, a genetic condition affecting collagen throughout the body, can produce changes in the temporal bone that look remarkably similar to cochlear otosclerosis on CT scans, though the involvement tends to be more severe and widespread.²¹ Paget’s disease of bone can also cause hearing loss through a similar mechanism of abnormal bone remodeling in the skull. The clinical context usually helps: osteogenesis imperfecta typically comes with a broader skeletal picture including fractures and sometimes blue sclerae, while Paget’s affects older patients and involves other bones. But in isolated temporal bone findings, the overlap can trip up even experienced radiologists.

High-resolution CT scanning is the main imaging tool used to support an otosclerosis diagnosis. A diagnostic protocol looks for telltale signs including areas of decreased bone density at a spot called the fissula ante fenestram (a small cleft just in front of the oval window) and around the cochlea, as well as new bone formation near the oval and round windows.²² In early or mild disease, though, imaging can be normal, and the diagnosis is confirmed only when a surgeon directly observes a fixed stapes during an operation.

Otosclerosis in the Archaeological Record

Otosclerosis is not a modern disease. Paleopathologists have identified it in human remains spanning thousands of years. A study of over 4,000 skulls from Lithuania, dating from the Neolithic through the 17th and 18th centuries, found eight cases of clinical otosclerosis, yielding a prevalence of about 0.19 percent.²³ The researchers noted that this rate is broadly similar to modern populations, suggesting that whatever causes otosclerosis has been operating for millennia and is not a product of industrialization or contemporary environmental exposures.

Advances in micro-CT scanning have made it possible to detect otosclerosis in ancient remains with much greater precision. A recent examination of an Early Bronze Age individual from Poland revealed classic features of the disease, including a low-density focus at the fissula ante fenestram and the so-called “double ring sign” around the cochlea.²⁴ That puts the oldest plausible case at roughly 4,000 to 5,000 years old. The archaeological record reinforces the genetic basis of the disease: if environmental triggers alone were responsible, you would expect the pattern to shift dramatically across different eras and living conditions, but it does not.

Diagnosing stapes fixation in skeletons is tricky, however. Another study examining over 600 ancient tympanic cavities initially identified four suspected cases but, after careful analysis, concluded that only two represented genuine fixation during life, one from ligament hardening and one likely congenital rather than otosclerotic. The other two turned out to be soil particles or mineral deposits formed after burial.²⁵ The lesson is that even in modern research using ancient specimens, otosclerosis mimics can fool investigators, much as they do in living patients.

1
Otology & Neurotology. Otosclerosis in an Urban Population
2
PubMed Central. Disability, Quality of Life and Hearing Function in Patients With Untreated Otosclerosis
3
PubMed Central. Imaging in otosclerosis: A pictorial review
4
PubMed Central. The Rise and Fall of Otosclerosis: A Population-based Study of Disease Incidence Spanning 70 Years
5
Otolaryngologic Clinics of North America. How Common Is Otosclerosis? Statistics and Risk Factors
6
PubMed. Genetics of otosclerosis
7
PubMed. Single-nucleotide polymorphisms in the COL1A1 regulatory regions are associated with otosclerosis
8
American Journal of Otolaryngology. Association of COL1A1 polymorphism in Turkish patients with otosclerosis
9
Nature Communications. Genome-wide screen of otosclerosis in population biobanks: 27 loci and shared associations with skeletal structure
10
PubMed Central. Otosclerosis and Measles: Do Measles Have a Role in Otosclerosis? A Review Article
11
PubMed Central. No evidence for an association between persistent measles virus infection and otosclerosis among patients with otosclerosis in Japan
12
PubMed. Absence of Measles Virus Detection from Stapes of Patients with Otosclerosis
13
PubMed Central. With the Incidence of Otosclerosis Declining, Should Stapedectomy Remain a Key-Indicator Case for Otolaryngology Residents?
14
PubMed. Effect of drinking water fluoridation on hearing of patients with otosclerosis in a low fluoride area: a follow-up study
15
PubMed. Effect of drinking water fluoridation on the prevalence of otosclerosis
16
PubMed Central. Cochlear otosclerosis
17
PubMed Central. Histopathological Patterns of Otosclerosis Progression: Exploring Otic Capsule and Round Window Involvement
18
Journal of Otolaryngology Research & Reports. Juvenile Otosclerosis: A Case Report
19
PubMed Central. Management of Juvenile Otosclerosis: A Systematic Review
20
Brazilian Journal of Otorhinolaryngology. Pediatric otosclerosis: Case report and literature review
21
Seminars in Ultrasound, CT and MRI. The otodystrophies: Diagnosis and differential diagnosis
22
PubMed. Diagnostic Protocol for Detecting Otosclerosis on High-Resolution Temporal Bone CT
23
The Journal of Laryngology & Otology. Clinical otosclerosis and auditory exostoses in ancient Europeans (investigation of Lithuanian paleoosteological samples)
24
International Journal of Osteoarchaeology. Micro‐CT Examination Reveals a Possible Case of Otosclerosis in an Early Bronze Age Individual From Poland
25
International Journal of Paleopathology. Diagnosis of stapedial footplate fixation in archaeological human remains