This article is on otosclerosis, a rare condition experienced by patients and seen by General Practitioners, Otolaryngologists, and Audiologists. This resource is open to everyone. Patients, Medical Students and Medical Professionals may find this useful. Adjacent boxes provide additional information for Medical Professionals.
What is Cholesteatoma?
Otosclerosis is a condition in which there is abnormal bone growth inside the ear. Sound passes into the cochlea (inner ear) through a chain of three tiny bones in the middle ear. The stapes bone is the final bone in the chain. In a healthy ear the stapes moves in and out like a piston to pass sound waves into the inner ear. The stapes can become fixed to the cochlea due to abnormal bone growth, and sound waves are no longer passed into the inner ear efficiently. Over time the stapes can become completely fixed to the cochlea causing a severe hearing loss.
Otosclerosis commonly causes hearing loss in one or both ears, and can also cause tinnitus (ringing in the ears), dizziness, and balance upset.
Who gets Otosclerosis?
Otosclerosis often runs in families. If you have relatives with otosclerosis you are more likely to develop otosclerosis but not all relatives of a person with otosclerosis will develop otosclerosis. Symptoms usually develop in young adults.
What are the causes?
The risk factors for otosclerosis are not fully understood, however known risk factors include:
- Family history of otosclerosis
- Association with previous measles infection
- Caucasian ethnicity??
- Pregnancy can worsen the symptoms of otosclerosis
- Women are more likely to get otosclerosis than men
What are the symptoms?
The main symptom of otosclerosis is hearing loss. Hearing loss typically gradually worsens over months to years. Most people with otosclerosis first notice hearing loss in their 20s or 30s.
Other symptoms may include:
- Ringing in the ears (tinnitus)
- Balance problems
How is it diagnosed?
Otosclerosis is diagnosed following examination by an Otolaryngologist and hearing testing by an Audiologist.
Most people with otosclerosis have a conductive hearing loss although some people will have a mixed (conductive and sensorineural) hearing loss. There are many other causes of conductive hearing loss which need to be ruled out before otosclerosis is suspected. The tympanic membrane (ear drum) and middle ear will usually appear normal, and the ear drum will show normal movement on tympanometry (pressure wave testing).
There is no single test to diagnose otosclerosis clinically or on hearing testing. The diagnosis is suspected when other causes have been ruled out. Diagnosis is confirmed at the time of surgery, when the middle ear is directly examined and fixation of the stapes bone is confirmed.
Increased vascularity may be visible on the promontory when viewed through the ear drum, indicating active otosclerosis. This is seen in around 10% of cases.
What are the potential complications?
Rarely abnormal bone growth can occur inside the cochlea (inner ear), causing a more severe hearing loss that cannot be improved with surgery. This is called cochlear otosclerosis.
What are the treatment options?
Otosclerosis can cause a mild to severe hearing loss. If the hearing loss is mild, observation may be recommended. More significant hearing loss can usually be successfully treated with hearing aids or surgery.
A hearing aid is an electronic device worn in or around the ear to increase the volume of sound entering the ear. There are minimal risks associated with hearing aids.
Surgery can be performed, which is called stapedectomy or stapedotomy. Part of the stapes bone is removed and replaced with a metal or plastic implant. The stapes bone is no longer fixed to the inner ear, allowing movement of sound waves into the inner ear. Hearing is improved in 80-90% of people who have surgery for otosclerosis.
Surgery is usually performed with the patient asleep under general anaesthesia. While the surgery is usually successful, risks of surgery include:
- worsened hearing loss – about 1 in 100
- new or worsened tinnitus or ringing in the ears
- balance upset or vertigo – usually temporary
- altered taste – usually temporary
- weakness of the facial muscles – very rare
Can you prevent Otosclerosis?
It is unknown if there are any ways to prevent otosclerosis
What is the prognosis?
Most people with otosclerosis can be successfully treated with hearing aids or surgery to give normal or near-normal hearing. Otosclerosis does not affect life expectancy.
Author + Affiliation:
Dr Rachael Bentall, Department of Otolaryngology, Waikato Hospital
Reviewed by Dr Shueh Lim, Otolaryngologist, Waikato Hospital
Date of Publication +/- Review: