Otosclerosis

Genesis of Otosclerosis

Otosclerosis means the fixation of the smallest auditory ossicle, the stirrup (stapes), due to alteration processes affecting the bones in the middle ear. Consequently, there is a disruption of the sound transmission in the middle ear, involving a mild sound sensitivity disorder. Usually, the affected patients suffer from a hearing loss which progresses in a series of stages. Frequently, the disease affects first one ear and later develops in the other ear as well.

Symptoms of Otosclerosis

Depending on where the otosclerosis occurs in the ear, it may involve different symptoms. Frequently, the alteration affects the auditory ossicles entailing a slowly progressive hearing loss due to the disruption of the sound transmission. In about 30 % of the patients, the disorder affects both ears. Tinnitus is another important symptom, being characterised by a low-pitched sound. Otosclerosis seldom affects the inner ear (cochlea). However, if this happens, the patient may suffer a complete hearing loss in severe cases.

Diagnosis of Otosclerosis

After two or three different examinations, it is generally possible to establish a reliable diagnosis. One suitable examination method, among the usal hearing tests, is the so-called “Gelle’s Test” which consists in generating a sound with the tuning fork while increasing the pressure in the ear canal, which causes a stiffening of the ossicular chain. If the sound of the tuning fork is perceived as loud as at normal pressure, the patient is likely to suffer from otosclerosis.

The computed tomography can help establish the diagnosis of otosclerosis, since it visualizes alterations of the bones.  
A threshold search audiometry can be performed to measure the conductive hearing loss of both air and bone conduction. The air conduction audiometry helps establish the hearing threshold, when the sound waves pass the ear canal and the middle ear, whereas the bone conduction measurement determines the hearing ability in the inner ear.

However, in some cases, a direct endoscopic inspection of the middle ear may be necessary to establish the diagnosis of otosclerosis.

Surgical Treatment of Otosclerosis

The hearing impairment caused by otosclerosis can generally be well repaired by a surgical intervention (stapesplasty). In this operation the immobilized stapes bone is first almost completely removed with the help of a microscope and finest surgical instruments and then replaced by a micro-implant made from titanium, which restores the sound transmission between the auditory ossicles and the inner ear. For the required opening of the stapes footplate we prefer a no-touch surgery by means of a CO2 laser.

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