What is Otosclerosis?
Otosclerosis is a condition that affects the middle ear, causing hearing loss. It occurs when abnormal bone growth in the middle ear prevents the small bones from functioning properly, leading to impaired sound transmission. The most common symptom of otosclerosis is gradually worsening hearing loss, typically beginning in the mid- to late-twenties. Other symptoms may include tinnitus (ringing in the ears) and a feeling of fullness in the affected ear.
Hearing loss from otosclerosis occurs when is blocked from reaching the inner ear. The last middle ear bone, the stapes or “stirrup,” becomes fixed. Because it is fixed, sound energy from the vibrating eardrum cannot be transferred to the inner ear. This results in a conductive hearing loss or a reduction in sound being "conducted" to the inner ear.
Outlined arrow points to plaque of otosclerosis on the hearing portion of the inner ear, the cochlea. Small arrow points to the oval window and stapes (not well visualized in this example). Case courtesy of A.Prof Frank Gaillard, Radiopedia
There are several treatment options for otosclerosis, including hearing aids and surgery. Surgery is the most effective option for restoring hearing in cases of severe or complete hearing loss. The most common surgical procedure for otosclerosis is called a stapedectomy, in which the abnormal bone growth is removed and replaced with a small prosthetic device. This allows the small bones in the middle ear to function properly again, improving sound transmission and hearing.
Hearing aids can help people with early otosclerosis who are not yet candidates for surgery. They can also help in far advanced otosclerosis (see below). The downsides to hearing aids is that they are expensive and may need to be every 5-7 years. The sound quality is also not as good as natural hearing. Surgery for otosclerosis can restore a wider frequency range which can make speech and music sound more natural.
Hearing aids and surgery do not help as much when otosclerosis is "far advanced." This stage of otosclerosis does not affect every patient. In the most common forms of otosclerosis, only the stapes is affected. In far advanced otosclerosis, sensorineural hearing loss occurs as the bone of the inner ear becomes affected. This limits its ability to translate vibrations into a nerve signal the brain can understand. Surgery cannot help this. Hearing aids can help but only do so much. When far advanced otosclerosis makes the phone a challenge, it's time to move beyond a hearing aid and consider cochlear implants.