WHAT IS OTOSCLEROSIS?

Otosclerosis, also known as middle ear ossification, is one of the common causes of hearing loss. Otosclerosis is a genetically inherited disease that can appear after skipping several generations.

The first stage of hearing involves the vibration of the eardrum as sound waves travel along the external auditory canal and reach the eardrum. These vibrations are transmitted to the tiny bones in the middle ear called the hammer, anvil, and stirrup, facilitating the transmission of sound to the inner ear fluids. Here, the sound waves are converted into electrical energy at the nerve endings and transmitted to the hearing centers in the brain via the auditory nerve, enabling hearing.

Problems that occur during the transmission of sound waves through the external and middle ear result in “conductive type hearing loss.” In these types of losses, the hearing organs in the inner ear are intact, but sound waves cannot reach them. Hearing losses originating from the inner ear and auditory nerve are referred to as “sensorineural type hearing loss.” In otosclerosis, which can also affect the inner ear, both types of hearing loss are typically observed together. These combined hearing losses are known as “mixed type hearing loss.”

HEARING LOSS ASSOCIATED WITH OTOSCLEROSIS

In otosclerosis, spongy-looking new bone formations develop in the bone structure housing the inner ear’s hearing organs. When these changes affect the hearing organs in the inner ear, “cochlear otosclerosis,” which refers to sensorineural hearing losses, occurs. The most frequently affected area in the disease is the oval window, where the stirrup (stapes) bone is located and transmits sound wave vibrations to the inner ear. The otosclerosis focus at the oval window impedes the movement of the stirrup bone, disrupting the transmission of sound waves to the inner ear and resulting in conductive type hearing loss.

The type and degree of hearing loss occurring in otosclerosis depend on the extent to which the movement of the stirrup bone is restricted and the degree to which the hearing organs in the inner ear are affected by the disease.

TREATMENT OF OTOSCLEROSIS

Medical Treatment:

In cases where otosclerosis is detected at a young age and progresses rapidly, certain treatments are used to slow the progression of hearing loss. However, there is no medical treatment available for otosclerosis.

Surgical Treatment:

In a “stapedectomy” surgery, the restricted-moving stirrup (stapes) bone is removed and replaced with a prosthesis that transmits sound waves to the inner ear. This surgery can be performed under local or general anesthesia and yields highly successful results in approximately 90-95% of cases. In the majority of patients, conductive type hearing loss is nearly completely corrected. Surgery is not recommended for patients with very mild conductive hearing loss or those with severe sensorineural hearing loss due to significant involvement of the inner ear hearing organs. For all other otosclerosis patients, stapedectomy surgery is recommended unless there is a serious health issue preventing the procedure. After surgery, patients may experience dizziness for a few days. Surgical sponges placed inside the ear are removed after 7-10 days, and patients can return to their normal lives shortly thereafter.

With appropriate surgical equipment and techniques, the risks associated with stapedectomy surgery are very low. However, there is approximately a 1% risk of hearing loss in every surgery. Other, much rarer complications include perforation of the eardrum, injury to the facial nerve, infection in the ear, and early dislodgment of the prosthesis.

Hearing Aids:

Every patient who can benefit from surgery can also benefit from hearing aids. Especially in patients with bilateral otosclerosis and those who opt out of surgery, using hearing aids is recommended to prevent the decline of inner ear functions that accompany decreasing hearing.