Otosclerosis

It is a condition of the bony labyrinth where irregularly laid spongy bone replaces normally dense enchondral bone. Most often this focus involves the stapes footplate region causing fixation to the stapes and conductive hearing loss.

Causes:

The exact cause of the condition is unknown, though many possibilities have been suggested.

• Presence of areas of cartilage rests which due to certain nonspecific factors are activated to form a new spongy bone.

• About 50% of the cases have a family history of the same condition.

• It may be initiated or made worse by pregnancy, menopause, after an accident or a major surgery.

Symptoms:

• Hearing loss which is insidious and progressive, usually affecting both ears. Hearing is usually better in noisy than in quiet surroundings.

• Tinnitus and vertigo are other uncommon symptoms.

Signs:

On examination the tympanic membrane appears normal. No major abnormalities are visible from the outside.

Investigations:

• Audiogram:  it shows a conductive hearing loss with a dip at 2000Hz in most cases.

• Tympanometry shows a normal curve in early stages but shows a As curve in later stages.

Management:

Surgical exploration with a stapedotomy is the preferred management as an effective medical management is not available. However, a hearing aid can be useful for performing daily activities.