Definition Otosclerosis involves the formation of new bone that affects two structures within the ear, known as the cochlea and labyrinth. The cochlea is a cone-shaped tube involved in hearing, and the labyrinth is key to a person's sense of balance.
What is going on in the body? When new bone forms over the inner ear structures, it can prevent the bones from vibrating normally. The bones are no longer able to transmit sound waves to the cochlea, and hearing is impaired. If the labyrinth is affected, the person's sense of balance can be impaired as well.
What are the signs and symptoms of the condition? The main complaint is a slowly progressive loss of hearing. It initially affects one ear, but both ears can be simultaneously affected. Many individuals develop problems in both ears.
What are the causes and risks of the condition? Many cases have no known cause. In others, there is a clear family history. Osteogenesis imperfecta, a genetic disease that causes bones to be brittle, often leads to otosclerosis. There is some thought that drinking non-fluoridated water may cause a susceptible person to develop otosclerosis as well.
What can be done to prevent the condition? There seems to have been a decline in otosclerosis with fluoridation of municipal water systems. If an individual with a positive family history does not have access to fluoridated water, then fluoride tablets are beneficial.
How is the condition diagnosed? Hearing tests generally show nerve function to be normal, but there is difficulty getting sound to the nerve through the abnormal bone formation. On the hearing tests, low frequencies are usually most severely affected. If there is some concern about nerve damage to the hearing or balance structures, a CT scan of the temporal bone can show abnormalities.
What are the long-term effects of the condition? There are no long-term effects if the bone growth stops. If the condition progresses and affects the more of the bones of the inner ear, nerve deafness or loss of balance can result.
What are the risks to others? There is no risk to others, as the condition is not contagious.
What are the treatments for the condition? Wearing a hearing aid can help improve hearing. There are surgical procedures as well that can bypass the affected bones. Fluoride tablets may help stabilise the condition and prevent further nerve damage.
What are the side effects of the treatments? The side effects of hearing aids mostly involve irritation from wearing them. With surgery there is slight possibility of nerve deafness and taste disturbances. Temporary dizziness is frequent but usually resolves.
What happens after treatment for the condition? Successful surgery usually, but not always, restores hearing.
How is the condition monitored? Any new or worsening symptoms should be reported to the doctor.
Author: Mark Loury, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
