Otosclerosis

What is otosclerosis?

Otosclerosis is a condition where abnormal bone growth in your middle ear stops a tiny bone, called the stapes, from vibrating properly. This gradually reduces your ability to hear, and it's a common cause of hearing loss in younger adults.

What are the symptoms of otosclerosis?

The most common symptom is hearing loss that develops gradually, often over several years. It usually starts in one ear before affecting both. You might also notice:

• Difficulty hearing low-pitched sounds or whispers, while still hearing loudly spoken words in noisy places
• Ringing, buzzing or other noises in one or both ears (tinnitus)
• Dizziness or problems with your balance
• Speaking quietly yourself, because your own voice sounds louder to you than it really is.

What are the causes of otosclerosis and who is at risk?

Doctors don't know exactly why otosclerosis happens. It occurs when the stapes, a tiny bone in your middle ear, fuses with the bone around it and can no longer move freely. This may be linked to:

• Genetics: otosclerosis often runs in families. If one parent has it, you have around a 25% chance of developing it too, rising to about 50% if both parents are affected
• Pregnancy: hormonal changes can trigger it, or make an existing case worse, in women who are already prone to the condition
• A previous measles infection or other viral illness
• Stress fractures in the bone surrounding your inner ear
• An immune system response affecting the bone.

You're more likely to develop otosclerosis if you have a close relative with the condition. It's most common in women, in white people and in people of Indian heritage, and typically first appears between the ages of 15 and 45. Rare genetic conditions such as osteogenesis imperfecta (brittle bone disease) can also increase your risk.

Are there different types of otosclerosis?

Otosclerosis develops in stages and can be classified in a few ways.

• Otospongiosis and otosclerosis: in the early stage, the new bone growth is soft (otospongiosis). Over time, it scars and hardens, at which point it's called otosclerosis.
• Conductive or mixed hearing loss: if otosclerosis only affects the stapes and other tiny bones in your middle ear, it causes conductive hearing loss. Rarely, it also affects your inner ear, causing mixed hearing loss, a combination of conductive and inner-ear hearing loss.
• Clinical or histological: many people have some otosclerosis in their ear bones without ever developing symptoms. It's only called clinical otosclerosis once it progresses enough to cause noticeable hearing loss.

How is otosclerosis diagnosed?

If you have symptoms of otosclerosis, your GP will examine your ears and ask about your symptoms and family history. They'll usually refer you to an audiologist for hearing tests, or to an ear, nose and throat (ENT) specialist, who will also look inside your ears.

Tests may include:

• An audiogram, which measures your hearing across a range of pitches
• A tympanogram, which checks how well your eardrum and middle ear conduct sound
• Sometimes, a CT scan, to look at the bones and structures inside your ear in detail.

How is otosclerosis treated?

Non-surgical treatment

If your hearing loss is mild, you may not need treatment straight away, and your doctor may simply monitor it with regular hearing tests. The main non-surgical option is a hearing aid, which makes sounds around you louder. Hearing aids can help you hear more easily, but they won't stop your hearing from getting worse.

Some doctors prescribe supplements such as sodium fluoride, calcium or vitamin D in the hope of slowing the condition down, though there isn't yet enough evidence to confirm how well this works.

Surgical treatment

The main surgical option is a stapedectomy, where a surgeon removes the affected stapes bone and replaces it with a small prosthesis made of plastic or metal. This bypasses the abnormal bone and allows sound to reach your inner ear again. Surgery is usually very successful at improving hearing. If both of your ears are affected, your surgeon will operate on one at a time, usually waiting at least six months between operations so each ear can heal.

If otosclerosis has spread to your inner ear, a cochlear implant may be recommended instead.

After surgery, protect your ear while it heals: avoid blowing your nose, being around people with coughs or colds, flying or diving, and loud noises. See your doctor promptly if you develop ear pain, dizziness or a fever afterwards, as these can be signs of infection.

When should I see a doctor?

See a GP if you think your hearing is gradually getting worse, or if you have tinnitus that's frequent, constant, getting worse, or affecting your sleep, concentration or mood. Getting a prompt diagnosis and starting treatment early can help ease your symptoms and improve your quality of life.