Otosclerosis: What It Is, How It Affects Hearing, and How It's Treated

Imagine trying to listen to someone whisper, but all you hear is muffled noise. Or sitting in a quiet room, and suddenly you can’t hear the low hum of a refrigerator-until you realize it’s not the fridge. It’s your own hearing slipping away. This is the reality for many people with otosclerosis, a quiet but progressive condition that hijacks sound by locking up a tiny bone in the middle ear.

What Exactly Is Otosclerosis?

Otosclerosis is not a tumor. It’s not an infection. It’s abnormal bone growth-specifically, the body’s own bone cells going rogue inside the middle ear. The target? The stapes, the smallest bone in the human body, about the size of a grain of rice. This bone is supposed to vibrate like a drumstick tapping a tambourine, passing sound from the eardrum to the inner ear. But in otosclerosis, new bone forms around the stapes, fusing it to the oval window-the doorway to the inner ear. Once it’s stuck, it can’t move. Sound doesn’t get through.

This isn’t sudden. It creeps in over years. People often notice it first when they struggle to hear low-pitched voices-like a man speaking or the bass in music. They might think their partner is mumbling, or that the TV volume is too low. But it’s not the sound. It’s the bone.

Who Gets Otosclerosis?

It’s not random. About 1 in 200 people in the UK have it. In the U.S., that’s roughly 3 million people. It’s most common in adults between 30 and 50. And women are far more likely to be affected-about 70% of cases. Why? Hormones may play a role. Many women first notice symptoms during pregnancy, when hormonal shifts seem to speed up the bone remodeling process.

Genetics matter too. If a parent or sibling has otosclerosis, your risk doubles. Researchers have found at least 15 genetic links, with the RELN gene on chromosome 7 being the strongest. It’s not a simple inherited trait, but if you have a family history, you’re definitely in a higher-risk group.

Ethnicity also plays a part. Otosclerosis is most common in people of European descent, less common in Asians, and rarest in African populations. That pattern has held for decades, even as global mobility has increased.

How It’s Diagnosed

Most people don’t go straight to an ear specialist. They start with their family doctor, who might suspect an ear infection or Eustachian tube dysfunction. In fact, about 22% of otosclerosis patients wait an average of 18 months before getting the right diagnosis.

The key is a hearing test-pure-tone audiometry. This test shows a clear gap between air conduction (sound through the ear canal) and bone conduction (sound through the skull). In otosclerosis, this gap is usually between 20 and 40 decibels. Speech tests usually come back normal, which helps rule out nerve damage. That’s a big clue: if you can understand words clearly but can’t hear them loudly enough, it’s likely a mechanical blockage-not a nerve problem.

Sometimes, a CT scan of the temporal bone reveals the telltale signs: small, dark spots where the abnormal bone is forming around the stapes. These foci are only 0.5 to 2.0 mm wide, but they’re enough to stop a bone from vibrating.

How It’s Different From Other Hearing Losses

Not all hearing loss is the same. Otosclerosis stands out because of what it affects and how it progresses.

- Noise-induced hearing loss hits high frequencies first-think bird songs, alarms, or the “s” sound in speech. Otosclerosis targets low frequencies, making voices sound dull or distant.

- Presbycusis, or age-related hearing loss, usually starts after 65 and affects high pitches. Otosclerosis hits younger adults and hits low pitches.

- Meniere’s disease comes with vertigo, ringing, and fluctuating hearing. Otosclerosis? Steady decline. No spinning. No sudden changes.

This distinction matters because treatment depends on the cause. You wouldn’t use surgery for noise-induced loss. But for otosclerosis? Surgery is often the best fix.

What Happens If It’s Left Untreated?

Left alone, otosclerosis doesn’t just stay the same. It gets worse. On average, untreated cases lose 15 to 20 decibels of hearing over five years. That’s not just a little quieter. It’s the difference between hearing a conversation at arm’s length and needing someone to shout.

In 10 to 15% of cases, the abnormal bone growth spreads to the inner ear-the cochlea. This turns a conductive hearing loss (mechanical) into a mixed or even sensorineural loss (nerve damage). Once the inner ear is involved, hearing aids become less effective, and surgery won’t help that part.

Tinnitus is another common companion. Around 80% of people with otosclerosis report ringing or buzzing in the ears. For 35% of them, it’s bad enough to disrupt sleep. That’s not just about hearing-it’s about quality of life.

Treatment Options: Hearing Aids vs. Surgery

There are two main paths: amplification or repair.

Hearing aids are the first step for many. They don’t fix the bone-they just make sound louder. About 65% of patients start here. Modern digital aids can be programmed to boost low frequencies specifically, which helps a lot. But they don’t stop the disease. And some people hate the way their own voice sounds when amplified-the “occlusion effect,” where your voice booms inside your head.

Surgery is the only way to fix the problem at its source. The gold standard is stapedotomy. Instead of removing the entire stapes (stapedectomy), surgeons drill a tiny hole in the footplate and insert a prosthetic piston-often made of titanium or platinum. This piston connects the incus (another middle ear bone) to the inner ear, bypassing the fused stapes. The eardrum stays intact. Recovery is quick: most people go home the same day.

Success rates? Around 90-95%. In 87% of cases, patients achieve functional hearing-meaning they can hear normal conversation without aids. One 45-year-old teacher in Florida said after her surgery, “I can finally hear my students whispering in the back row.”

But surgery isn’t risk-free. About 1% of patients experience sudden, permanent sensorineural hearing loss in the operated ear. That’s rare-but devastating. That’s why informed consent is critical. You need to know the odds before you sign.

What’s New in Treatment?

The field isn’t standing still. In March 2024, the FDA approved a new prosthesis called StapesSound™. It’s coated with titanium-nitride, which reduces scar tissue and adhesions after surgery. Early trials show a 94% success rate at one year-up from 89% with older models.

There’s also promising drug research. Sodium fluoride, long used for osteoporosis, is now being tested to slow bone growth in otosclerosis. A 2024 study found patients taking it had 37% less hearing decline over two years compared to those on placebo. It’s not a cure, but it might buy time-especially for people who aren’t ready for surgery.

The biggest future shift? Genetic screening. Researchers are working on polygenic risk scores that could identify high-risk individuals before symptoms even appear. Within five years, we might be able to test young adults with a family history-and start monitoring or even intervening early.

Why Fewer Surgeons Are Doing It

Here’s the catch: stapedotomy is a highly specialized procedure. It requires precision under a microscope, deep knowledge of middle ear anatomy, and years of training. Mount Sinai requires surgeons to complete 50 supervised cases before they’re allowed to operate alone.

But fewer young otolaryngologists are choosing to specialize in this. Many are focusing on cochlear implants or head and neck cancer. As a result, stapedectomy procedures in the U.S. have dropped 15% since 2018. That means access is becoming harder in some areas. If you’re diagnosed, you may need to travel to find a surgeon with the right experience.

Living With Otosclerosis

If you’ve been diagnosed, you’re not alone. The Hearing Loss Association of America has over 1,200 members in its otosclerosis support group. Many report the same struggles: avoiding phone calls, turning up the TV too loud, feeling isolated in group conversations.

But the outlook is hopeful. With early diagnosis, most people can keep their hearing functional for life. Whether through hearing aids, surgery, or a combination, the vast majority regain the ability to connect with the world around them.

The key is not to wait. If you’ve had unexplained hearing loss for more than six months-if low voices sound muffled, if you’re constantly asking people to repeat themselves-get your hearing tested. Don’t assume it’s just aging. It might be something fixable.

When to See a Specialist

See an otolaryngologist (ear, nose, and throat doctor) if:

• Your hearing loss is worse in one ear
• You notice difficulty hearing low-pitched sounds
• You have a family history of hearing loss
• You’ve had tinnitus for more than a few weeks
• Audiometry shows an air-bone gap

Don’t wait for it to get worse. Otosclerosis doesn’t reverse itself. But it doesn’t have to control your life either.