What is Otosclerosis?
Otosclerosis is an abnormal bone growth of the bones in the middle ear. The name and definition of otosclerosis come from the greek words “oto” (ear) and “skleros” (hard). Otosclerosis is caused by an abnormal growth of bone tissue in the ears, which affects the ability to hear. In otosclerosis, the stapes ("stirrup" bone) begins to fuse with the surrounding bone, eventually becoming fixed so it cannot move. This means that the transmission of sound into the inner ear is reduced.
In its early stages, the sufferer will normally not be affected. In most cases, a surgical operation will restore the hearing.
Types of otosclerosis
There are two types of otosclerosis: Fenestral Otosclerosis and Retrofenestral Otosclerosis also called Cochlear Otosclerosis.
How does otosclerosis cause hearing loss?
Otosclerosis has to do with the three small bones in the middle ear, more specifically the stapes. A part of the stapes bone will grow abnormally and this abnormal bone growth will prevent the stapes from vibrating normally in response to sound. The stapes is vital for transmitting sound waves from the outer ear, through the middle ear and into the inner ear. When the stapes does not move properly, the sound that is sent from the middle ear into the inner ear is reduced which causes a hearing loss.
What causes otosclerosis?
Otosclerosis is often inherited, although isolated cases do occur. For instance, measles and pregnancy have been observed as potential causes for worsening the case of otosclerosis.
As otosclerosis is typically inherited, it is a genetic hearing loss.
What are the symptoms of otosclerosis?
The main symptom of otosclerosis is a hearing loss.
Otosclerosis often causes a progressive conductive hearing loss. A progressive hearing loss is a hearing loss that gets worse (more severe) over time. As the stapes grows, the transmission of sound is more and more reduced and the hearing loss will gradually be stronger.
Other otosclerosis symptoms
Signs of otosclerosis may also appear in the form of dizziness, balance problems (vertigo) and tinnitus.
Strong background noise can add to the confusion of people with nerve deafness, but in the case of otosclerosis, this confusion does not often occur. Sometimes the person may even hear better in noisy surroundings (paracusis), possibly because of the high frequency and loudness of other people's voices in those circumstances.
Otosclerosis often tends to affect low frequency sounds more than high frequency sounds.
Read more about low-frequency hearing loss and high-frequency hearing loss.
How is otosclerosis diagnosed?
Otosclerosis is diagnosed by a medical examination of the middle ear, typically by an ENT-doctor or a hearing professional. But some signs of otosclerosis can be detected by the patient or the relatives as they experience a gradual loss of hearing.
The diagnosis and treatment of otosclerosis is relatively straight-forward. It is however important to consult a specialist as soon as possible and to plan the course of treatment.
Treatment of otosclerosis
The treatment of otosclerosis can be divided into two types of treatment:
- The use of hearing aids or other hearing instruments
- Surgery of the stapes (stapedectomy).
Hearing aids help people who are suffering from conductive deafness, including otosclerosis. However, a hearing aid will not cure the deafness. Since the hearing loss is progressive when having otosclerosis, more powerful hearing aids or hearing implants may be needed as time goes by. In the early stages, hearing aids are a great help for those who do not wish to undergo surgery.
Surgery for otosclerosis
Surgical operations for alleviating otosclerosis fall into the field of otorhinolaryngology. The relatively simple procedures are widely performed to reinstate hearing and cure otosclerosis. In a stapedectomy, which is a stapes surgery, either the part of the stapes with the abnormal bone growth is removed in order to insert a tiny implant (stapedotomy), or the stapes bone is replaced by a small prosthesis (stapedectomy). Both surgeries of the stapes can restore hearing. In many of the cases, the symptoms of vertigo and tinnitus will also disappear.
What should I do if I think I have otosclerosis?
If you think that you have otosclerosis, for example because others in your family have it, as it is often inherited, you should contact a doctor or a hearing professional to have your middle ear examined and have your hearing tested.