Vestibular disease
Otosclerosis
This information is intended as a general introduction to this topic. As everyone is affected differently by balance and dizziness problems, you should speak to your doctor for individual advice.
For reasons of better readability, the generic masculine is used and the simultaneous use of the language forms male, female and diverse (m/f/d) is dispensed with. Unless otherwise indicated, the personal designations used in this patient information refer to all genders.

What is otosclerosis?
Otosclerosis is a complex disorder of abnormal bone growth in the middle ear. It usually occurs when the tiny stapes bone grows together with the surrounding bone. Otosclerosis usually leads to a slow, progressive conductive hearing loss.
If the stapes can no longer vibrate, hearing is impaired. Sound waves can no longer travel efficiently from the eardrum to the inner ear. Advanced otosclerosis can cause dizziness and affect balance, especially if the abnormal bone growth extends into the inner ear.
Sometimes the hearing loss in otosclerosis is relatively mild and remains so. However, it usually worsens gradually. This can happen quickly or over many years. Otosclerosis can lead to severe hearing loss, but rarely to complete deafness.
In around 70 - 80 % of cases, otosclerosis affects both ears (bilateral). In the early stages of the disease, patients often report hearing loss in only one ear (unilateral).
Otosclerosis is one of the most common causes of hearing loss in young adults. In most cases, hearing loss is first noticed in the teens and twenties. Otosclerosis can also occur in children and older people. Women are about twice as likely to develop otosclerosis as men. Pregnancy can cause otosclerosis to progress more quickly.
Otosclerosis is rare and occurs in around 3 in 1,000 people. Research suggests that 25-50% of people with otosclerosis have a family history of the disease.
The word otosclerosis comes from the Greek. It means an abnormal hardening of the tissue (sclerosis) in the ear (oto).
How do we listen?
To understand why otosclerosis causes hearing loss, it is important to have a basic understanding of how we hear. For hearing to function normally, a sound must pass through all three parts of the ear: the outer, middle and inner ear. The outer and middle ear are filled with air, but the inner ear is filled with fluid.
The outer ear consists of the pinna and the funnel-shaped external auditory canal. The pinna collects sound waves (vibrations) and transmits them through the ear canal to the eardrum. This causes the eardrum to vibrate and converts the sound waves into mechanical vibrations.
These vibrations are transmitted to three tiny bones (hammer, anvil and stirrup) in the air-filled space of the middle ear. These bones, also known as ossicles, are arranged in such a way that they amplify the vibrations.
The stapes, the innermost bone, is connected to the cochlea in the inner ear. The cochlea contains tiny hairs and fluid. When the stapes vibrates against a "window" in the wall of the cochlea, the fluid moves. This causes the hairs to bend and generate electrical signals. These signals are sent to the brain via the vestibulocochlear nerve (8th cranial nerve) and interpreted as sound.
Hearing is impaired in otosclerosis when the stapes grows together with the surrounding bones of the middle ear. The stapes can no longer vibrate and sound is no longer transmitted efficiently from the eardrum to the inner ear.
Types of hearing loss in otosclerosis
There are different types of hearing loss in otosclerosis:
- Conductive hearing loss occurs in the early stages of otosclerosis when the mechanical transmission of sound is impaired by bone remodeling processes in one or all of the bones of the middle ear. Most people with otosclerosis suffer from conductive hearing loss. This process usually reaches its peak when those affected are in their thirties.
- Sensorineural hearing loss occurs later when the bone surrounding the inner ear (otic capsule) is remodeled. This process is called otospongiosis. The mineral density decreases and the bone becomes spongy as it remodels. It is thought that enzymes from the bone enter the inner ear and cause sensorineural hearing loss. Atrophy (shrinkage) of the outer wall of the cochlear duct (spiral ligament) and deterioration of its blood vessels (stria vascularis) also contribute to sensorineural hearing loss in otosclerosis.
- Mixed conductive and sensorineural hearing loss:
Mixed hearing loss in all frequencies occurs in the final, most advanced stage, when otosclerosis extends to the bone surrounding the inner ear (otic capsule) or the bony labyrinth of the inner ear.
Summary
- A complex disorder with abnormal bone growth in the middle ear.
- Tiny bones that conduct sound grow together with the surrounding bones.
- Usually affects both ears.
- One of the most common causes of conductive hearing loss in young adults. The speed and extent of hearing loss are unpredictable.
- Causes dizziness and balance problems if the bone growth reaches the inner ear.
- Hearing aids are usually the first choice for treatment.
- In 80% of patients, hearing improves after minimally invasive surgery.
- A healthy lifestyle generally helps to cope better with the challenges of adjusting to unexpected hearing loss.
What causes otosclerosis?
Bone is a living tissue that is constantly being broken down and newly formed. In otosclerosis, the process of bone remodeling does not work properly and abnormal bone forms. Science does not yet know exactly why this happens.
Possible causes include
- A faulty gene inherited from one parent. Researchers have recently identified a number of changes in the SERPINF1 gene that can cause otosclerosis.
- Exposure to the measles virus could play an important role in the activation of a gene responsible for otosclerosis. The exact role of measles in the development and progression of otosclerosis is not yet clear. The decline in measles cases due to vaccination could contribute to a further reduction in the number of people with otosclerosis.
- Stress fractures of the bones in the ear and the bony tissue surrounding the inner ear.
- Some studies suggest that an autoimmune response of the body, possibly related to environmental or genetic factors, may be associated with otosclerosis.
Changes in hormone levels during pregnancy may play a role in exacerbating otosclerosis. One study found that women with otosclerosis in both ears lost 33% of their hearing after a single pregnancy.
Otosclerosis often occurs together with a rare disease called brittle bone disease (osteogenesis imperfecta).
The symptoms of otosclerosis include
- Gradually progressive hearing loss.
- Some people report difficulty hearing lower or quieter sounds and whispers.
- Some people report that they find it easier to hear with background noise. This is called paracusis willisii.
- Speaking quietly because your voice seems too loud.
- Tinnitus affects over 50% of people with otosclerosis.
- Rotational vertigo and balance disorders occur in around 30% of those affected. Vertigo occurs when the otosclerosis has invaded the inner ear and damaged the macular organs and/or the semicircular canals.
The symptoms of otosclerosis can be difficult to distinguish from other causes of hearing loss. These include various mechanical disorders of the middle ear bones (ossicles), fluid in the middle ear (otitis media with effusion or serous otitis media) and even other inner ear diseases such as semicircular canal dehiscence (SCD syndrome).
Diagnosis of otosclerosis
Go to your GP if you are worried about your hearing. Your GP will then refer you to an ENT specialist who will examine you thoroughly. ENT specialists work closely with hearing aid acousticians.
You will probably have some of these diagnostic tests done:
- Complete hearing examination including tests to measure hearing sensitivity (audiogram) and sound conduction in the middle ear (tympanogram).
- Stapedius reflex test to analyze the movement of the stapes in your ear. In this test, the ear to be examined is exposed to loud sounds. The test is quick and painless.
High-resolution computed tomography (CT) is gradually being used for the diagnosis and surgical planning of otosclerosis. It shows variants in the patient's anatomy and the severity of the disease, including involvement of the cochlea.
Some of the diagnostic tests are performed to rule out other diseases or health problems. Tumors (including acoustic neuroma), semicircular canal dehiscence (SCD syndrome) and Ménière's disease are among the conditions with similar symptoms. Your doctor must consider all possibilities before making a diagnosis and setting up a treatment plan.
Treatment of otosclerosis
The treatment for otosclerosis depends on the severity and type of hearing loss, the patient's age and general health and preferences. Your doctor will talk to you about the risks and benefits of each treatment.
Approaches for the treatment of otosclerosis include:
Therapy option

Observation
The progression of otosclerosis varies in severity and speed for different people. Some people only have a slight hearing loss. For others, it takes many years for their hearing to deteriorate. Your doctor may suggest testing your hearing at least once a year. If your hearing continues to deteriorate, they may recommend a hearing aid.
Therapy option

Medical treatment
There are no medications that have been proven to improve hearing in people with otosclerosis. Fluoride therapy has been used in the past but is no longer recommended because of its negative effects on the hip and other bones. There is little or conflicting evidence that taking sodium fluoride is helpful for otosclerosis.
Therapy option

Hearing aids
If the otosclerosis has not progressed beyond the middle ear, hearing aids are usually the first choice for correcting conductive hearing loss. They are a less risky alternative to surgery.
When you decide on a hearing aid, you will work with a hearing care professional to select and fit a suitable device. Hearing aids can be adjusted to amplify only the frequencies you need based on your hearing tests. As the disease progresses, the amplification can be increased as needed.
Bone conduction hearing aids or bone anchored hearing aids (e.g. BAHA) are an option for patients who
- cannot or do not want to undergo surgery for otosclerosis
- who have difficulty wearing conventional hearing aids or do not benefit from them
Therapy option

Operation
Stirrup plasty corrects conductive hearing loss by restoring the mechanical transmission of sound through the middle ear. However, it cannot correct sensorineural hearing loss. Stirrup surgery is being performed less and less frequently and is usually only considered when less invasive treatments have been unsuccessful for a patient.
Stirrup plasty is considered a minimally invasive procedure. There are two surgical variants:
- Stapedotomy
The surgeon makes a small incision above the ear canal (endaural approach). The eardrum is lifted to reach the middle ear. The upper half of the stapes is removed. A small hole is made on the underside (footplate) of the stapes and a prosthesis (artificial replacement) is inserted in place of the defective bone. - Stapedectomy
This procedure is similar to the stapedotomy. The main difference is that the incision is larger and is made inside the ear canal and the entire stapes is removed.
Of the two procedures, stapedotomy is generally preferred. It is less invasive, has fewer complications and leads to better hearing results at high frequencies.
80% of patients have significantly better hearing after the operation. The improvement in hearing may not be noticeable immediately after the operation. Hearing usually improves as the swelling subsides in the first three weeks after surgery. It can take up to three months for the inner ear and eardrum to recover. Maximum hearing is achieved after about six months.
However, the operation cannot eliminate the tinnitus. It also does not improve hearing if the hair cells in the cochlea are affected by otosclerosis.
To be considered for stapes surgery, patients must demonstrate good bilateral (both ears) inner ear function in a series of hearing tests.
The "red flags" that rule out surgery include
- a poor physical condition
- Fluctuating hearing loss with dizziness
- Torn eardrum
- Infection
- Hearing tests outside the norm
Surgical risks and complications are rare, but can occur:
- Further hearing impairment occurs in about 2% of cases and can have various causes.
- A perforation (hole) in the eardrum only occurs in around 1% of cases. It is usually caused by an infection and heals by itself. If not, the hole can be repaired by surgery (myringoplasty).
- Injury to the facial nerve is usually transient. Leakage of fluid from the inner ear (known as "gusher phenomenon") is possible if cerebrospinal fluid escapes through the surgical opening because of an abnormal connection to the brain cavity. This is very rare and can be corrected with a lumbar drain (a small flexible tube inserted into the lumbar spine).
- Taste disorders and dry mouth are common in the first few weeks after the operation. These disorders persist in around 5% of cases.
- Tinnitus can develop or worsen.
- Dizziness and balance disorders, which generally improve over time and can be treated with vestibular rehabilitation. The brain learns to maintain its balance again and to react appropriately to signals from the vestibular and visual systems.
- The prosthesis can change its position over time. It can penetrate the middle part of the bony inner ear labyrinth (vestibule) and cause immediate hearing loss.
In most patients, the otosclerosis continues to progress after the operation. For this reason, 10 to 20 % of patients require a second operation (revision). The success rate for revision surgery is around 75%.
Therapy option

Cochlear implant
A cochlear implant is a rare treatment option and is often only used after unsuccessful otosclerosis surgery. A cochlear implant (CI) is an electronic device that partially restores sensorineural hearing loss. It carries the risk of impairing balance.
Living with otosclerosis
It can be challenging to accept and live with otosclerosis, especially for young adults. A healthy lifestyle generally helps to better manage the challenges that come with unexpected hearing loss. Helpful strategies therefore include:
- Relaxation techniques
- Balanced diet
- Sufficient sleep
- Physical activity
What happens next?
What you can expect in the future.
The progression of otosclerosis varies from person to person. It is not possible to predict how quickly or to what extent your hearing will be affected. Regular hearing tests and advice on how best to treat and manage your condition will continue to be necessary in the years to come.
Using a new DNA sequencing technique known as whole exome sequencing (WES for short), researchers recently succeeded in identifying the first gene involved in the development of otosclerosis. The research team is continuing to work on identifying further otosclerosis genes. They are also investigating how mutations in the identified genes cause otosclerosis.
Other research studies deal with, among other things:
- the role of inflammatory or autoimmune diseases in otosclerosis
- Bisphosphonates (a class of medication that stops the loss of bone density) and vitamin D supplementation as possible treatment methods
It is hoped that research will lead to the development of drugs to treat or prevent otosclerosis.
In order to keep this patient information as short as possible, we have not included a detailed list of references. However, this can be requested at any time at info@ivrt.de.