When most people schedule an appointment for a diagnostic hearing evaluation, they may expect to learn they have hearing loss. What they might not expect to learn is that their hearing loss is caused by a relatively rare condition known as otosclerosis.
According to the National Institute on Deafness and Communication Disorders, otosclerosis is a term derived from oto, meaning “of the ear,” and sclerosis, meaning “abnormal hardening of body tissue.”
Otosclerosis is caused by abnormal bone remodeling in the middle ear. Bone remodeling is a lifelong process in which bone tissue renews itself by replacing old tissue with new. In otosclerosis, abnormal remodeling disrupts the ability of sound to travel from the middle ear to the inner ear.
Otosclerosis affects more than 3 million Americans. Many cases of otosclerosis are thought to be inherited, with white, middle-aged women most at risk.
What causes otosclerosis?
Otosclerosis is most often caused when one of the bones in the middle ear, the stapes, becomes stuck in place. When this bone is unable to vibrate, sound is unable to travel through the ear and hearing becomes impaired.
Why this happens is still unclear, but scientists think it could be related to a previous measles infection, stress fractures to the bony tissue surrounding the inner ear, or immune disorders. There also seems to be a genetic link to otosclerosis and it tends to run in families.
It may also have to do with the interaction among three different immune-system cells known as cytokines. Researchers believe that the proper balance of these three substances is necessary for healthy bone remodeling and that an imbalance in their levels could cause the kind of abnormal remodeling that occurs in otosclerosis.
What are the symptoms of otosclerosis?
Hearing loss is the most common symptom of otosclerosis. It typically starts in one ear and then moves to the other. This loss may appear very gradually. Many people with otosclerosis first notice that they are unable to hear low-pitched sounds or can’t hear a whisper. Some people may also experience dizziness, balance problems, or a ringing, roaring, buzzing, or hissing in the ears or head that sometimes occurs with hearing loss.
How is otosclerosis diagnosed?
Otosclerosis is often detected through case history and a thorough diagnostic audiological evaluation by an audiologist. These tests include an audiogram, which measures hearing sensitivity, and tympanometry, which checks middle-ear sound condition. It is diagnosed by an otolaryngologist (commonly called an ENT because they are doctors who specialize in diseases of the ears, nose, throat and neck), or an otologist (a doctor who specializes in diseases of the ear).
How is otosclerosis treated?
If an audiologist or other provider detects otosclerosis, a referral may be made to an otolaryngologist or otologist for further assessment and formal diagnosis. Unfortunately, there is no effective drug therapy to treat otosclerosis at this time.
Instead, mild otosclerosis may be treated with a hearing aid that amplifies sound, but in more severe or advanced cases, surgery may be required. In a procedure known as a stapedectomy, a surgeon inserts a prosthetic device into the middle ear to bypass the abnormal bone and permit sound waves to travel to the inner ear and restore hearing. Even patients who have surgery may still need hearing aids to help them hear.
A doctoral-level audiologist can conduct a diagnostic hearing evaluation, the gold-standard of care, to determine whether you have a hearing loss, and can make referrals to a specialist if a medical condition such as otosclerosis is suspected.