Otosclerosis: The Middle Ear Condition That Causes Gradual Hearing Loss

Most people associate hearing loss with aging or noise exposure. But there is another cause that affects younger adults more than most people realize: otosclerosis.

Otosclerosis is a condition where abnormal bone growth develops in the middle ear, specifically around the stapes, the smallest bone in the body. The stapes is supposed to vibrate freely in response to sound waves, transmitting vibrations from the eardrum to the inner ear. When otosclerosis restricts its movement, sound transmission is reduced and hearing declines.

It is one of the most common causes of conductive hearing loss in adults between the ages of 20 and 50.

How it develops

The middle ear contains three tiny bones called ossicles: the malleus, incus, and stapes. They form a chain that amplifies sound vibrations from the eardrum and delivers them to the cochlea in the inner ear.

In otosclerosis, abnormal spongy bone grows around the footplate of the stapes where it connects to the oval window of the cochlea. As this growth progresses, the stapes becomes increasingly fixed in place. Less vibration reaches the inner ear, and hearing gradually declines.

The process is slow, typically developing over months to years. Most people notice it first as difficulty hearing soft speech or low-pitched sounds.

Who gets it

Otosclerosis has a strong genetic component. About half of people with the condition have a family history of it. It is more common in women than men, and symptoms often appear or worsen during pregnancy, suggesting a hormonal influence.

It most commonly presents between ages 20 and 40. It affects both ears in about 70 percent of cases, though one ear usually progresses faster than the other.

Caucasian populations have the highest rates. The condition is less common in people of African and Asian descent, though it occurs in all ethnic groups.

Symptoms

The hallmark symptoms of otosclerosis include:

Gradual hearing loss. This is usually the first and most noticeable symptom. It develops slowly, often over several years. Many people do not realize how much hearing they have lost until the deficit is substantial.

Difficulty hearing low-pitched sounds. Unlike age-related hearing loss, which typically affects high frequencies first, otosclerosis often begins with low-frequency hearing loss. You may find that deep voices are harder to hear than high-pitched ones.

Hearing better in noisy environments. This is a paradoxical symptom called paracusis of Willis. Background noise causes people to speak louder, which compensates for the conductive loss. Some people with otosclerosis feel they hear better at a busy restaurant than in a quiet room.

Tinnitus. Ringing, buzzing, or humming in one or both ears is common with otosclerosis. It can range from mild to quite intrusive.

Dizziness. In some cases, the abnormal bone growth affects the inner ear structures near the stapes, causing balance disturbances. This is less common but can occur as the condition progresses.

Diagnosis

Otosclerosis is diagnosed through a combination of hearing tests and clinical evaluation:

Pure tone audiometry shows a characteristic pattern: an air-bone gap, meaning that hearing through headphones (air conduction) is worse than hearing through bone vibration (bone conduction). This gap confirms that the problem is in the middle ear, not the inner ear.

Tympanometry may show reduced eardrum movement as the stiffened stapes restricts the mobility of the entire ossicular chain.

Acoustic reflex testing often shows absent or reduced reflexes in the affected ear, which is a strong indicator of stapes fixation.

CT imaging can sometimes visualize the abnormal bone growth, though it is not always necessary for diagnosis if the audiometric findings are characteristic.

Your audiologist will identify the conductive hearing loss pattern and refer you to an ENT specialist for confirmation and treatment discussion.

Treatment options

Hearing aids. Because otosclerosis causes a conductive loss with the inner ear often still functioning normally, hearing aids work exceptionally well. They simply need to amplify sound enough to overcome the mechanical block in the middle ear. Many patients with mild to moderate otosclerosis achieve excellent hearing with well-fitted hearing aids and choose not to pursue surgery.

Stapedectomy or stapedotomy. This is a surgical procedure where the fixed stapes is partially or fully removed and replaced with a tiny prosthetic piston. The prosthesis restores the vibration pathway to the inner ear.

Stapedectomy is one of the most successful surgeries in all of medicine. About 90 to 95 percent of patients experience significant hearing improvement. The surgery is performed under local or general anaesthesia, usually as a day procedure, and most people return to normal activities within one to two weeks.

Risks are low but include a small chance of further hearing loss, taste disturbance (a nerve to the tongue runs through the middle ear), dizziness, and tinnitus. The risk of serious complications is less than 1 percent in experienced hands.

Sodium fluoride. Some ENT specialists prescribe sodium fluoride supplements to slow the progression of otosclerosis. The evidence for its effectiveness is mixed, but it may help stabilize hearing in some patients. It does not reverse existing bone growth.

Observation. In cases where the hearing loss is mild and not significantly affecting quality of life, monitoring with periodic hearing tests is a reasonable approach. Otosclerosis progresses at different rates in different people, and some cases stabilize without treatment.

Living with otosclerosis

If you choose hearing aids over surgery, or while you are deciding, a few strategies help:

• Face the person speaking and reduce background noise when possible
• Let people know about your hearing loss so they can speak clearly
• Use assistive listening devices in challenging environments like meetings or lectures
• Monitor your hearing with annual audiograms so changes are caught early

If surgery is performed, follow-up audiograms confirm the result and monitor for any recurrence. About 1 percent of stapedectomy patients experience a return of hearing loss years later if new bone growth occurs around the prosthesis.

Getting assessed in Edmonton

At Medicine Place Hearing Care, we can identify otosclerosis through comprehensive audiometric testing and refer you to an ENT specialist for evaluation. If hearing aids are the right path, we will fit and program them specifically for your conductive loss pattern.

Book a hearing assessment at Medicine Place Hearing Care in Edmonton.