Managing Hearing Loss With Otosclerosis

Otosclerosis is a type of hearing loss caused by the abnormal growth of spongelike bony tissue in the middle ear. This condition is often inherited, though evidence also links it to viral infections or autoimmune diseases.

The abnormal tissue growth that characterizes otosclerosis causes the stapes—one of the three tiny ear bones that vibrate in response to sound—to get stuck in place. This leads to hearing loss that worsens over time, though it rarely causes total deafness.

This article provides details about otosclerosis symptoms, diagnosis, and treatment.    

Otosclerosis Diagnosis: How to Tell If You Have Symptoms

Though it’s a common cause of middle ear hearing loss in young adults, otosclerosis doesn’t always affect hearing. Some people with the condition experience histological otosclerosis, meaning there’s abnormal bone growth in the ear, but it doesn’t affect your ability to hear.

Symptoms of Otosclerosis

Symptomatic, or clinical, cases of otosclerosis affect your hearing. Whites have higher reported rates of the condition than people of other races or ethnicities, affecting between 0.3% and 0.4% of people in this population. Being assigned female at birth is another risk factor, with the median (most common) age of onset 42 years.

Typical signs of otosclerosis include:

• Hearing loss: About 80% of people with otosclerosis experience hearing loss in both ears, but the initial onset tends to be in just one. Hearing loss progresses gradually. The earliest reported symptoms among most people with the condition include difficulty hearing low-pitched sounds or whispers.
• Tinnitus: An estimated 50% of people with otosclerosis experience tinnitus, a high-pitched ringing or buzzing in the ears that can be constant or come and go.
• Vertigo: The sensation that everything is spinning or moving past you (vertigo) is present in about 10% of otosclerosis cases. This symptom can cause loss of balance and dizziness.

Otosclerosis Diagnosis

If you suspect you have otosclerosis or are experiencing hearing loss, you’ll be referred to an ear nose and throat (ENT) specialist (otolaryngologist), otologist (ear specialist), or audiologist (hearing disorder specialist) for diagnosis. Alongside an evaluation of your medical status and history, a healthcare provider may perform one or more of the following tests:

• Audiogram: This test assesses your hearing sensitivity by using tones of different frequencies and noting the volume of each when you detect it.
• Tympanogram: To see how well your middle ear is functioning, this test measures how much your eardrum (tympanic membrane) moves in response to sound.
• Imaging: In some cases, a computed tomography (CT) scan—a type of X-ray—or other imaging allows your provider to visually assess bone growth in the middle ear.  

Otosclerosis Effect on Hearing

Hearing loss caused by otosclerosis is progressive. It tends to worsen over time and goes through these three distinct phases:

• Otospongiosis: In the first phase, there’s elevated activity among osteoclast cells, which absorb old bone structure and the development of small blood vessels. This phase is most associated with sensory hearing loss, which arises due to damage in the inner ear.
• Transitional phase: Osteoblasts—cells that grow new bone—start to form spongy tissue in the middle ear.
• Otosclerotic phase: In the final phase, the spongy tissue deposits harden and mature into rigid bone, which affects stapes mobility. This hardening causes conductive hearing loss, in which sound cannot transmit from the outer to the inner ear.

Goal of Otosclerosis Treatment

While otosclerosis can significantly impact your hearing, treatment approaches effectively restore some associated hearing loss. A healthcare provider will tailor specific treatment based on the type and progression of the condition.

Hearing Aids

Hearing aids help amplify sounds so you can hear them and are an effective treatment for milder cases of otosclerosis. These wearable devices essentially take sound from the outside, make it louder, and direct it to the inner ear, thus increasing your hearing sensitivity.

Bone Conduction Implants

If the cochlea of the inner ear is still healthy, a healthcare provider will recommend bone conduction implants to amplify sound. These work by converting sounds into vibrations transmitted to the inner ear.

A device implanted in the inner ear on the temporal bone (part of the lower side walls of the skull) interacts with an external receiver placed behind the ear. It is effective for conductive hearing loss in one ear, though it can also help with minor sensory hearing loss.   

Surgery

The two primary surgeries for otosclerosis, which are highly successful in restoring some or all hearing functions, are stapedectomy and stapedotomy. Both types of surgeries are necessary in 10% to 20% of cases as they progress. These surgeries aim to restore stapes function, which treats conductive hearing loss. With the advent of laser-assisted middle ear surgery several decades ago, the vast majority of surgeries are staped.

Summary

Otosclerosis is a type of hearing loss caused by the abnormal growth of bony tissue in the middle ear. It is a progressive condition causing the stapes—a small ear bone critical for hearing—to become stuck, reducing hearing. In addition, abnormal bone growth can affect structures of the inner ear. Diagnosis involves hearing tests and imaging. Surgery on the middle ear, implanted hearing devices, and hearing aids help restore hearing function.