Otosclerosis is a disease that occurs as a result of abnormal bone formation in the middle ear and inner ear. If this new bone formation begins to prevent the transmission of sound to the inner ear, which is the main hearing organ, hearing loss occurs in the patient.
What is the cause of otosclerosis?
The exact cause of otosclerosis is unknown. However, there is a familial (hereditary) transmission in some patients. It has also been claimed that there is a relationship between measles virus and otosclerosis disease. The disease is more common in middle-aged women. However, it can also be seen in men and even children.
How do we hear?
The middle ear is responsible for amplifying and transmitting sound vibrations from the eardrum to the inner ear. This function is performed with the help of 3 ossicles in the middle ear:
Malleus (hammer) is located at the outermost, attached to the eardrum.
Incus (anvil) is located in the middle.
Stapes (stirrup) is between the incus and the oval window opening to the inner ear and transmits the vibrations transmitted to it by other ossicles to the inner ear.
Sound vibrations transmitted by the stapes ossicle to the oval window and inner ear fluids cause fluctuations in the inner ear fluids. These fluctuations are transformed into electrical signals by the sensory organs in the cochlea (snail), the hearing-related part of the inner ear. These signals are transmitted to the brainstem and from there to the brain via the auditory nerve.
How does otosclerosis cause hearing loss?
In otosclerosis patients, new bone formation often settles at the base of the stapes (stirrup) ossicle, preventing it from moving. obstructs and causes loss of sound transmission to the inner ear. In this case, the patient develops conductive hearing loss.
New bone formation caused by this disease sometimes settles in the inner ear wall. It also causes 'sensorineural' loss originating from the inner ear by affecting the cochlea (snail) directly or indirectly. This type of hearing loss, in which 'sensorineural' loss is added to conductive hearing loss, is called 'mixed' hearing loss. In more than half of the patients, both ears are affected by the disease, although not at the same level.
What are the symptoms of otosclerosis?
In most patients, The complaint that requires consulting a doctor is unilateral or bilateral hearing loss. The loss develops slowly and the patient initially notices that he or she cannot hear only soft sounds (such as whispers). Some of the patients state that they hear mutual conversations better in noisy environments.
The second most common complaint is ringing in the diseased ear (tinnitus). More rarely, there may be complaints of dizziness or mild imbalance.
How is otosclerosis diagnosed?
When the patient is examined by an Ear, Nose and Throat physician, the eardrums generally appear normal. Hearing measurements made in sound-insulated cabins using an examination instrument called a tuning fork or special devices called an audiometer make the diagnosis. The hearing measurement result called 'audiogram' also evaluates whether the disease has reached a stage that can be corrected by surgery.
Despite all the examinations and diagnostic examinations performed before the surgery, the definitive diagnosis is made during the surgery in patients with conductive hearing loss. . This means that, when the middle ear is examined during surgery in some patients who are operated on with a preliminary diagnosis of otosclerosis, it may be revealed that the problem causing hearing loss is due to another ear disorder other than otosclerosis. In this case, the improvement in hearing that can be achieved through surgery may be at a lower level, and it may even be impossible to correct the problem with surgery.
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