Otosclerosis is a pathological process involving the region of the inner ear and it is a relatively common cause of hearing disorders and other troubles. To understand the issue, we have to know some information about the anatomy of the ear and the transmission of sound sensations.
Sound is a mechanical vibration that is "captured" by our funnel-like ears and it passes through the outer ear canal to the eardrum, which vibrates. From the eardrum, the vibration is transferred through the middle ear by three tiny bones - the hammer, anvil and stirrup - to the inner ear. The inner ear contains the auditory organ itself, the so-called cochlea, which is located in a bony labyrinth. The cochlea is able to convert the vibrations into nerve impulses and these are transferred into the brain.
The otosclerosis affects the middle ear and its little bones and also the bony labyrinth of the inner ear. The most commonly affected site is the connection between the stirrup and the cochlea. The result is impaired mobility of the stirrup and disruption of transmission of the sound vibrations to the cochlea.
Scheme - the area in the red circle is the place affected by otosclerosis
Although a certain level of degeneration of the bony apparatus of the inner and middle ear occurs during the life in the majority of people, the typical otosclerosis occurs in young people, often between the ages of 30-40 years. It is assumed that it is a result of genetically inherited disorder with possible contribution of hormonal effects as the disease is more common in women.
The main symptom is gradual hearing loss and the patient may sometimes suffer from irritating sounds (buzzing, rustling) in the affected ear (so-called tinnitus). Due to a possible disruption of nearby-located vestibular apparatus, dizziness and other stability disorders can occur as well.
The patient with the above stated symptoms is usually examined by an otolaryngologist. The doctor can directly examine the outer ear canal and the eardrum, the middle and inner ear can be indirectly examined thanks to audiometry. The audiometry helps us to confirm the hearing loss, to evaluate its severity and possible location of the pathology.
The conservative means of therapy are very limited and there is not a substantial chance to influence the course of the disease without surgical intervention. Surgical procedures have much better outcome, but they must be performed by a skilled surgeon. During the procedure, the affected bones of the middle ear are removed and replaced with implants.