Brief overview
- Treatment: Injection with cortisone medication, hearing aid, long-term surgery to replace all or part of the stapes bone in the ear with a prosthesis
- Symptoms: Increasing hearing loss, untreated to the point of deafness, often ringing in the ears (tinnitus), rarely dizziness
- Causes and risk factors: Exact cause unknown, possibly infections (measles), hormonal influences, genetically hereditary causes, women are more frequently affected, symptoms often occur during pregnancy and the menopause
- Diagnostics: Various hearing tests
- Prognosis: Good prognosis with surgery, deafness is usually the result if left untreated
- Prevention: If there is a known predisposition in the family, regular check-ups with an ear, nose and throat specialist are advisable.
What is otosclerosis?
Otosclerosis is a disease of the middle and inner ear in which parts of the ear harden and ossify. This impairs the transmission of sound from the middle to the inner ear. The ossification usually begins in the middle ear and often spreads to the inner ear as it progresses.
Disturbed bone metabolism
Sound waves received by the ear cause the eardrum at the end of the external auditory canal to vibrate. This is transmitted to the ossicular chain in the middle ear – three tiny ossicles called the malleus, incus and stapes, which are connected in series.
Sound is transmitted from the malleus, which is in contact with the eardrum, via the incus to the stapes, which is connected to the membrane of the oval window – the entrance to the inner ear. From there, the acoustic information reaches the brain via the auditory nerve.
In otosclerosis, the bone metabolism in the area of the labyrinth capsule (bone in the area of the inner ear) is disturbed. As a rule, the first changes occur at the oval window. From there, the ossification spreads to the stapes, which is in contact with the membrane in the oval window: The stapes becomes increasingly immobile, which increasingly disrupts sound transmission and eventually makes it impossible.
Frequency
Otosclerosis is more common between the ages of 20 and 40. However, changes in the ear can sometimes occur as early as childhood without symptoms becoming apparent.
How can otosclerosis be treated?
If otosclerosis is not treated, the ossification increases steadily. Doctors speak of a progressive course. Deterioration cannot be halted with medication. Over a certain period of time, injections with preparations containing cortisone can alleviate the hearing loss.
In many cases, hearing aids also help to improve hearing. In the long term, however, it is not possible to prevent hearing from deteriorating continuously. This means that living with a diagnosis of otosclerosis is generally possible with restrictions.
Otosclerosis surgery: stapedectomy
Doctors speak of an “ectomy” when something is removed. In a stapedectomy, the entire stapes is removed – either using surgical instruments or a laser. The treating doctor then inserts an artificial replacement (prosthesis).
Like the stapes itself, the prosthesis is connected at one end to the anvil and at the other end to the membrane of the oval window. It thus completely fulfills the function of the stapes, so that sound transmission is once again guaranteed.
Otosclerosis surgery: stapedotomy
Stapedotomy is the second possible surgical method for otosclerosis. In the past, stapedectomy was generally used. Today, however, stapedotomy is preferred due to the lower risks involved.
The operation is usually performed under local anesthesia, more rarely under general anesthesia. The doctor injects the anesthetic into the external auditory canal. The eardrum is detached on one side to make the stapes accessible. After the operation, the surgeon folds back the eardrum.
The operation usually takes no longer than half an hour. The patient wears a special ear bandage (ear tamponade) for at least two weeks after the operation. However, the success of the operation becomes apparent – if not already during the operation – at the latest during these two weeks.
Treatment of capsular otosclerosis
If capsular otosclerosis (i.e. ossification that has spread to the inner ear) already exists, not only sound conduction but also sound perception is usually impaired. A sound perception disorder cannot be eliminated with a stapedectomy or a stapedotomy, as the cause of the hearing disorder lies in the inner ear.
If bilateral, severe sensorineural hearing loss due to capsular otosclerosis can no longer be sufficiently improved with hearing aids, cochlear implantation is the treatment of choice.
After the operation
After otosclerosis surgery, patients usually stay in hospital for three to five days. After around four to six weeks, patients are fully recovered from the operation – and in most cases no longer have any symptoms.
Patients often return to work after just three to four weeks.
What are the symptoms?
Otosclerosis leads to a progressive deterioration in hearing, usually only in one ear at first. In around 70 percent of those affected, otosclerosis later also develops in the second ear.
With increasing ossification, the mobility of the auditory ossicles is increasingly restricted. Eventually, this can lead to complete hearing loss (deafness).
Around 80 percent of otosclerosis patients also suffer from ear noises such as buzzing or humming (tinnitus).
Many patients report that they hear better than usual in a noisy environment (for example during a train journey) (Paracusis Willisii), especially their conversation partners.
Doctors explain this by the fact that disturbing noises at lower pitches are heard less well (and are therefore less disturbing for those affected) and, in particular, the conversation partners speak louder in the noisy environment.
Causes and risk factors
The exact links in the development of otosclerosis have not yet been clarified. Doctors suspect that various factors play a role. Possible causes include viral infections (measles, mumps or rubella) and autoimmune processes.
In autoimmune diseases, the immune system fights its own tissue. In some cases, otosclerosis is a concomitant symptom of so-called brittle bone disease (osteogenesis imperfecta).
Otosclerosis occurs more frequently in some families. If one parent suffers from otosclerosis, the children have an increased risk of also developing the disease. Doctors therefore suspect that the disease is based on a genetic predisposition.
In women, the first signs of otosclerosis often occur during pregnancy, and less frequently during the menopause.
An increase in symptoms is observed in women with the disease who are taking the contraceptive pill. It is therefore assumed that female sex hormones also play a role in otosclerosis. An increased concentration of female sex hormones may accelerate the remodeling processes of the bone.
A connection between nutrition and otosclerosis or hearing loss in general is occasionally discussed in connection with vitamins such as vitamin D. However, there is insufficient evidence to date. So far, however, there is insufficient scientific evidence for this.
Examinations and diagnosis
An ear, nose and throat specialist (ENT specialist) is the right person to consult if you have hearing difficulties. During an initial consultation, the doctor will take your medical history (anamnesis). You will have the opportunity to describe in detail any complaints you have noticed. In order to further narrow down the nature and origin of the complaints, the doctor will ask questions such as:
- Have you recently suffered from a viral or bacterial infection?
- Have you ever had such complaints in the past?
- Have you had an accident recently?
Physical examination
After taking a medical history, a physical examination is carried out. First, the doctor looks into the ear with a pneumatic magnifying glass (otoscopy) – this allows the mobility of the eardrum to be examined. In doing so, he detects any changes in the external auditory canal and the eardrum.
If inflammation is the cause of the hearing problems, this can be recognized by a clear reddening of the ear canal and eardrum. In people with otosclerosis, on the other hand, the ear canal and eardrum are completely unremarkable. Only in very severe cases does a kind of reddish spot shimmer through the eardrum (the so-called Schwartze sign).
Hearing test
Hearing tests (audiometry) characteristically reveal a loss in a certain frequency range between 1 and 4 kilohertz. This characteristic is known as the Carhart depression.
With the different test variants (so-called Rinne test, Weber test and Gellé test), the doctor finds out whether the hearing loss is due to a sound conduction disorder or a sound perception disorder. In the case of conductive hearing loss, the sound waves are not transmitted in the outer or middle ear. In the case of sensorineural hearing loss, the hearing impairment originates in the inner ear, auditory nerve or brain.
In the case of otosclerosis, where the ossification is exclusively in the middle ear, sound conduction is impaired. In the case of changes in the inner ear (capsular otosclerosis), the perception of sound is impaired. There are also mixed forms with otosclerotic changes in both the middle and inner ear.
If these changes are only present in one ear, this can be determined by comparison with the other ear. If the changes are present in both ears, this examination is not conclusive and further examinations are necessary.
Further examinations
During a speech test (speech audiogram), the doctor tests whether affected people have difficulty hearing spoken words.
Imaging procedures are used to directly detect changes in the bones. Magnetic resonance imaging (MRI) and computer tomography make the extent of the otosclerosis visible. The images can also be used to rule out dislocations or fractures (e.g. following trauma) of the bones.
An X-ray examination is useful in individual cases.
The doctor will also only perform a tympano-cochlear scintigraphy (TCS) (an imaging procedure using a slightly radioactive contrast agent) and a test of the sense of balance in certain cases.
Course of the disease and prognosis
The prognosis of otosclerosis depends on whether and when it is treated. Without treatment, the ossification in the ear usually leads to severe hearing loss or even deafness.
The earlier otosclerosis patients undergo surgery and follow-up treatment, the better the chances of a complete cure.
The symptoms after the operation are occasional feelings of dizziness. However, this usually disappears within five days. In a few cases, the dizziness lasts longer. Only occasionally does hearing deteriorate as a result of the operation.
Prevention
Otosclerosis cannot be prevented. However, people with family members suffering from otosclerosis are well advised to visit an ear specialist regularly to have signs of otosclerosis diagnosed early.
It is also advisable to consult an ear, nose and throat specialist immediately if you have general hearing problems or tinnitus. They will examine the ears for changes and, if necessary, perform an operation at an early stage. This reduces the risk of severe progression and possibly permanent damage due to otosclerosis.
