Otosclerosis is a hereditary condition that causes abnormal bone growth within the middle ear and causes gradual hearing loss over time. Affecting around 1 in every 200 people, otosclerosis tends to run in families. Typically presenting alongside hormonal changes, otosclerosis often develops during pregnancy and affects more women than men.
There are three tiny bones in the inner ear, and otosclerosis sees one of these – the stapes ( ‘stirrup’ bone) – fuse with the bone surrounding it, preventing it from moving as the eardrum vibrates. Because it can’t move, it cannot pass the vibrations to the microscopic hair cells inside the cochlea, which stops sound from efficiently transmitting to the inner ear.
Otosclerosis can develop in just one or both ears.
While the exact causes of the condition are unknown, one likely otosclerosis cause is a hereditary factor. One study found that a family history of the condition was reported in more than half of the patients presenting with otosclerosis. Patients with a positive family history also have an earlier onset of otosclerosis.
Menopause, trauma or undergoing a major operation have been associated with either causing or aggravating otosclerosis, too, as has infection with measles (significantly fewer people who have been vaccinated against measles develop otosclerosis), drinking non-fluoridated water and a genetic disorder called osteogenesis imperfect
The most common symptoms associated with otosclerosis include gradual hearing loss; difficulty hearing low-pitched sounds while finding it easier to hear in situations with background noise; tinnitus; dizziness and vertigo; and balance issues.
The condition may affect one ear or both, with its severity varying from case to case.
An otosclerosis diagnosis may be confirmed through a combination of medical imaging and hearing tests. When it comes to diagnosing otosclerosis, audiograms (measuring hearing sensitivity) and tympanograms (measuring middle ear conduction) can help determine the type of hearing loss experienced and its extent. These are both common tests performed during a hearing assessment.
Otosclerosis typically causes conductive hearing loss, so the audiologist conducting the testing will look for any signs that it is present. Medical imaging, such as an MRI or CT scan, may also be used to identify potential damage to the labyrinth (the innermost part of the ear) or the cochlear nerve, as well as any excess bone growth.
The good news is there are treatments available for otosclerosis. However, if the symptoms of the condition go unnoticed or are ignored, it will continue to worsen and – while rare – can affect the inner ear.
Otosclerosis is the most common cause of hearing loss, affecting 1 in 200 people. Women are twice as likely as men to develop otosclerosis, and Caucasians are more widely affected than other ethnic groups.
In most people with the condition – 70 to 80 percent – both ears are affected. Otosclerosis tends to develop in the teens and early 20s, but symptoms may not appear until a person reaches their 40s.
Otosclerosis hearing loss can be managed, and for those living with otosclerosis, there are two main treatment options: hearing aids or surgery. As a non-surgical treatment approach, hearing aids carry fewer risks of complications.
There is also some research to suggest that certain supplements – fluoride, calcium and vitamin D – may help slow the condition's progression. However, studies are limited and further investigation is required to determine their reliability as a treatment option.
Mild cases of otosclerosis may not initially require treatment, but the progression of the condition must be monitored closely. Regular hearing tests make it easier to identify if there has been any progression in the hearing loss experienced or if any additional symptoms have developed.
Surgery may be an option for those diagnosed with otosclerosis. One of two procedures may be performed: a stapedectomy or a stapedotomy.
A stapedectomy is a procedure that sees a surgeon remove the affected stapes, replacing it with a plastic or metal prosthesis. The prosthesis helps to restore the normal movement of the delicate bones within the ear, assisting in restoring the patient’s hearing.
A stapedotomy is similar to a stapedectomy, but rather than removing the stapes, a small hole is made in the footplate of the stapes using a medical laser. A prosthesis is then inserted into the hole, helping to improve the movement of the tiny middle ear bones.
The success rate of otosclerosis surgery is high, with the procedures successfully restoring the hearing of those living with otosclerosis in more than 90 per cent of cases. As with any form of surgery, however, it is important to remember some risks accompany otosclerosis surgery. These include further or total hearing loss, the development or worsening of tinnitus, vertigo, an altered sense of taste and facial weakness.
Before you decide whether to proceed with surgery, it’s a good idea to discuss the potential risks with your surgeon.