The ear consists of an outer, middle and inner part. Sound travels through the external ear canal in order to reach the ear drum and cause it to vibrate. This vibration is then transmitted through three small bones (ossicles) found in the middle ear. Those are called malleus, incus and stapes and form the ossicular chain. Sound then enters the inner ear where the nerve cells are. The inner ear is called the labyrinth, is snail shaped and contains fluid. The wave created in this fluid stimulates the inner ear nerve cells. Those produce nerve signals that are carried to the brain where they are interpreted as sound.
What is Otosclerosis?
Otosclerosis is a disease of the bone covering the inner ear. It can cause hearing deterioration when abnormal bone forms around the stapes to prevent sound reaching the inner ear. This can cause reduced movement of the ossicular chain causing conductive hearing loss. Less frequently otosclerosis can further affect the nerve of hearing causing also what we call sensorineural hearing loss.
The causes of otosclerosis are not fully understood even thought it tends to run in families and can be hereditary. People who have a family history of otosclerosis are more likely to develop the disorder. It can usually affect both ears but occasionally only one ear. It is usually prominent in the teens and early twenties. Research also shows a link between otosclerosis and hormonal changes associated with pregnancy.
What are the symptoms and how is otosclerosis diagnosed?
The commonest symptom is hearing loss and this can take several years to become obvious. The degree of hearing loss can range from mild to severe. It can also be conductive, sensorineural or mixed in nature. In addition to that some people might experience tinnitus or noise in the ear. The intensity of tinnitus is not necessarily associated with the degree or nature of hearing loss. Less commonly otosclerosis can cause dizziness. An ENT surgeon needs to diagnose otosclerosis with careful examination and special tests.
How is otosclerosis treated?
There is no medication to treat otosclerosis. The possible treatment options are:
- No treatment
- Hearing aid
- Surgery (Stapedectomy)
No treatment is needed if the hearing loss is mild. Hearing aids amplify sound without risks. Your ENT Surgeon together with the audiologist will advice you on what type of hearing aids meet your needs.
What is stapedectomy?
Stapedectomy is a surgical operation that can achieve restoration or improvement of hearing caused by stapedectomy.
If only one ear is affected then surgery can help restore hearing in that particular ear as well as generally improve hearing in the presence of background noise. In case both ears are affected the operation is initially performed in the worse ear.
The operation usually takes 2 hours under a general anaesthetic even though occasionally it can be done under a local anaesthetic. A small cut is made above the ear opening or inside the ear canal. The upper part of the stapes , the last of the ossicles in the ossicular chain, is removed with microsurgical instruments under the microscope. Following that, a small hole is made an the base of the stapes to gain access to the inner ear. In certain cases a small piece of vein from the back of the hand is needed which is used as a graft in the ear. A plastic or metal prosthesis is then placed in the ear, which joins the remaining ossicles and reconstructs the ossicular chain. At the end, a pack is placed in the ear canal to promote healing.
How successful is stapedectomy?
The success rate in experienced hands is over 80%. That means that 8 in 10 patients will notice hearing improvement up to the level that their ear is capable of hearing.
What are the possible complications?
Complications are rare but they should always be discussed with the surgeon.
- Hearing loss: In a small number of patients further or even total hearing loss can occur in the operated ear. In experienced hands this happens in 1 in 100 patients
- Dizziness: Dizziness is usually temporary in the first few hours after surgery. Occasionally some unsteadiness might occur for a few days or weeks after the operation. Permanent dizziness is very rare.
- Taste changes: The nerve that supplies the front of the tongue with taste runs immediately behind the ear drum. If this is damaged then an altered taste sensation can occur. This is usually temporary and only rarely permanent.
- Tinnitus: Occasionally Tinnitus can occur usually associated with hearing loss.
What happens after the operation?
You usually need to stay in hospital overnight.
If skin sutures are not absorbable then they need to be removed 7 days after the operation.
Ear packing is removed 2 weeks after the operation.
You should keep your ear dry the first 3 weeks after the operation. Using ear plugs in the bath or shower can be. Straining and heavy lifting must be avoided for a few weeks. Nose blowing should also be avoided. Flying and diving is not allowed for at least 6 weeks.