Otosclerosis
Otosclerosis (or otospongiosis) is a disease characterized by a limited lesion of the bone capsule, the so—called labyrinth of the inner ear, which results in the development of ankylosis of the stirrup, which can lead to conductive hearing loss (or conductive otosclerosis). Also, a consequence of the development of the disease may be a disorder of the functioning of the apparatus responsible for the perception of sound, and the onset of sensorineural type of hearing loss (the so-called cochlear otosclerosis). In addition to hearing loss, otosclerosis of the ear can also be manifested by characteristic ear noise, ear pain, dizziness and the presence of neurasthenic syndrome. As for the diagnosis of such a disease, it implies audiometry, X-ray sighting, otoscopy, threshold audiometry, stabilography, and more. Doctors often prescribe surgical treatment to improve the patient’s hearing. If we talk about conservative therapy, it is aimed at stopping the otosclerotic process.
The content of the article:
Pathogenesis of otosclerosis
Classification of otosclerosis
Causes of otosclerosis
Symptoms and manifestations of otosclerosis of the ear
Diagnosis of otosclerosis
Treatment and prevention of otosclerosis
Otosclerosis
As you know, today otosclerosis occurs in 1% of the population. An interesting fact is that the majority of cases are women (about 80%). Usually, the symptoms of otosclerosis appear only at the age of 20. This disease is characterized by its slow development and constant course, and it begins with a lesion of one ear. As you know, otosclerosis affects two ears, but the development of the disease in the second ear begins a few months after the disease of the first. Unilateral otosclerosis is rare (it is observed in 3% of patients). Symptoms are significantly aggravated in pregnant women.
Pathogenesis of otosclerosis
The main feature of the bone capsule of the labyrinth is its representation in the form of primary and bone formed during embryogenesis without the presence of secondary ossification. In the case of otosclerosis, as is known, the process in which mature bone is formed can be activated in different parts of the bone labyrinth. At the very beginning, there is the formation of immature, and as it is often called, spongy bone tissue, which contains a large number of vessels. It is such a focus of otosclerosis that is active. Further, the immature bone tissue of this focus is modified into sclerosed mature bone.
It is known that the foci of otosclerosis themselves have a multiple character. Doctors detect 50% of all cases of otosclerosis already in the area of the vestibule window, whereas only 30% are in the snail capsule itself, and about 15% are in the areas of semicircular tubules.
If the focus of otosclerosis is located in the area of the vestibule window, then this can lead to a sclerotic process, affecting the base of the stirrup with the further development of ankylosis. As a result, the immobilized state of the stirrup and the violation of the sound—conducting function of the ear, and hence, subsequently, the development of conductive hearing loss. If the focus of otosclerosis is located in the staircase of the labyrinth itself, then there is a malfunction of the apparatus responsible for sound perception. The latter leads to the possible appearance of sensorineural hearing loss.
Classification of otosclerosis
The classification of otosclerosis depends on the degree of violation of sound conduction and sound perception. There are three forms of otosclerosis:
conductive otosclerosis;
mixed form of otosclerosis;
cochlear otosclerosis.
The first form of conductive otosclerosis is usually characterized by a course with a violation of only sound conduction. Conducting a threshold audiogram, the doctor notes a noticeable increase in the thresholds of air conduction, despite the fact that bone conduction remains within normal limits. Otosclerosis of this form is considered the most favorable for the patient to transfer, and all because the treatment gives a quick and good effect, in the future completely restoring hearing.
As for the mixed form of otosclerosis, it is characterized by a reduced degree of hearing due to characteristic violations of sound transmission and due to manifested disorders of sound perception. Threshold audiogram, as a rule, reveals an increased level of thresholds of both air and bone conduction. If the operation is performed in a timely manner, then the patient’s hearing will return to the level of bone conduction.
The third characteristic form of otosclerosis is cochlear otosclerosis: it is usually expressed in a severe violation of the sound—receiving function of the ear. With this form, the threshold of bone conduction is 40 dB or more. A surgical operation can restore hearing to the level of bone conduction, but this will not be enough to fully restore hearing.
If otosclerosis is classified according to the nature of the symptoms, then slow, abrupt and transient types are distinguished. The development of any type of otosclerosis involves three periods, among which: the initial period, the period of the most pronounced clinical manifestations and the terminal period.
Causes of otosclerosis
Today there are several theories about the etiology of otosclerosis, among which the hereditary theory occupies a significant place. According to the researchers, often the occurrence and development of the disease is transmitted through the hereditary line and is associated with the presence of genetic defects in the parents. Also, we should not forget about the connection of the disease with metabolic and endocrine changes in the body, which is especially pronounced in pregnant women.
Another famous theory is the theory of infectious exposure, which is associated with a genetically determined predisposition to otosclerosis. As recent research by scientists has shown, such an impact can be a consequence of measles. Other authors say that impaired blood supply to the bone capsule, as well as calcification of cartilage tissue may also be characteristic factors.
Symptoms and manifestations of otosclerosis of the ear
The onset of otosclerosis of the ear is usually asymptomatic. It is also often called the histological stage of the disease. However, at this stage, changes occur in the very structure of the bone tissue of the labyrinth, while clinical manifestations are still absent. In rare cases, the disease is characterized by a very rapid course, accompanied by the development of sensorineural hearing loss. In most cases, the initial stage lasts about 2 years, during which the patient notes a slight noise in the ear, which appears periodically. As for hearing loss, it may be insignificant at this stage and can only be detected during audiometry.
As mentioned earlier, at the beginning of the disease, an inconspicuous hearing loss is characteristic, which is expressed in a violation of the perception of low tones, while the perception of high tones remains the same. Usually patients complain of slurred male speech, while female speech and the speech of children are heard well by the patient. Further, the observation of paracuzis Willis is characteristic, in other words, an apparent (imaginary) improvement in the state of hearing in a noisy environment. It should be said that noise in otosclerosis does not affect the perception of certain sounds at all.
Another possible symptom of otosclerosis may be Weber’s paracusis, that is, a deterioration in perceived speech when listening to other sounds that are directed to the cochlea in parallel. This symptom is observed especially during walking and chewing food.
As the disease develops, there is a noticeable deterioration in hearing with a characteristic violation of the perception of low and high tones. Also, the patient may not perceive whispered speech, and understanding ordinary speech will be difficult. It should also be said that the hearing loss accompanying otosclerosis never assumes a regressive character, but it can only be its more deepened form. It is possible that the progression of this symptom is associated with overwork, as well as endocrine rearrangements in the body (childbirth, pregnancy, menstruation). Hearing with otosclerosis can fall to the 3rd stage, but complete deafness is not terrible for the patient.
Another characteristic symptom of otosclerosis is noise in the ear, which occurs in more than 80% of patients. The main distinguishing feature of this symptom is the lack of correlation of pronounced ear noise with the degree of hearing loss. Such a noise is somewhat reminiscent of the noise of primus or the rustle of leaves. Researchers believe that such noise is primarily associated with metabolic and circulatory disorders occurring in the cochlea.
An integral symptom of otosclerosis of the ear is earache, which occurs during the exacerbation of this inflammatory process. It should be said that the pain has a special bursting character, and its location is observed in the area of the mastoid process. Usually, after the occurrence of another pain syndrome, the patient has an even greater hearing loss.
Dizziness is a symptom that is extremely rare. Such a symptom may be transient in nature or may simply be poorly expressed. If patients have a neurasthenic syndrome, then we can say that it is caused by hearing impairment. Hearing loss does not allow the patient to feel fully in society, so often patients simply avoid communication, becoming withdrawn and apathetic natures. There may also be a sleep disturbance.
Diagnosis of otosclerosis
Usually, the first thing patients come to an otolaryngologist with, not knowing that they have otosclerosis, is complaints of noise in the ear and hearing impairment. The first task of any otolaryngologist is to differentiate otosclerosis from many other possible causes of hearing loss. When diagnosing otosclerosis, it is important not to confuse it with chronic purulent otitis media, cholesteatomas, ear tumor, adhesive otitis media, ankylosis of the stirrup, Meniere’s disease and others. To do this, the otolaryngologist prescribes an otoscopy and a detailed examination of the ear.
With the help of otoscopy or microtoscopy, it is possible to identify the Holmgren triad (sulfur absent in the ear, dry skin in the auditory canal and reduced skin sensitivity in case of irritation). It should be said that with otosclerosis, there is no change in the eardrum. In the case of atrophy, the Schwartz spot (translucent mucous membrane of the tympanic cavity in the place affected by atrophy) will be an indirect sign of otosclerosis.
Also, for the purpose of diagnosis, audiometry is performed, which is designed to determine a violation of the perception of speech in a whisper. When examining with a tuning fork, it can be revealed whether the conductivity of sounds through tissues is increased or not. The result of threshold audiometry will depend on the form of otosclerosis itself.
Acoustic impedance measurement can be an auxiliary method for diagnosing otosclerosis. But to distinguish, for example, otosclerosis from cochlear neuritis, you can use ultrasound research, which is not at all disturbed in this disease.
In the case of vestibular function examination (by indirect otolithometry or vestibulometry of stabilography), hyporeflexia was detected in more than 60% of patients, while hyperreflexia was detected in 15%. Approximately 20% of patients have the disease without any vestibular disorders. If the patient feels dizzy, then it is urgently necessary to consult with a vestibulologist or an otoneurologist. With the help of X-ray of the skull, it is possible to determine changes in the bone tissue of the labyrinth capsule. But a more accurate result, of course, will show a CT scan of the skull, with which you can visualize the foci of otosclerosis on the monitor.
Treatment and prevention of otosclerosis
If we talk about the treatment of otosclerosis, then the most effective way is surgical intervention, which will improve the mechanism of transmission of sound vibrations at the level of the auditory ossicles by transferring it to the perilymph of the labyrinth. The operation is expedient, first of all, for those whose bone conduction decreased by at least 25 dB, while the air conduction was no more than 50 dB. If the patient has hearing loss, then the operation is contraindicated for him.
Today , three types of operations are common in surgery:
mobilization of the stirrup;
fenestration of the labyrinth;
stapedoplasty.
The purpose of the first type of operation is to release the stirrup from the bone splices that contributed to its immobilization. The second type of operation is aimed at creating a completely new window in the wall of the threshold of the labyrinth. It should be said that the effect of these two types of operations is very unstable. Hearing improvement can only be for several years, and it is possible that after a while hearing loss will continue to progress.
As for the third type of surgery — stapedoplasty — it is the most effective, consolidating the achieved result for a long time. During stapedoplasty, a prosthesis is implanted, which replaces the stirrup. This type of operation is possible both with and without stapedectomy. In case of non-use of stapedectomy, the fixation of the prosthesis to the anvil is usually performed using a hole that is made at the base of the stirrup. Usually, a stirrup prosthesis is made either from cartilage tissue or from the bone of the patient himself. Titanium, ceramics and Teflon are also used. This type of surgery is performed only on the ear that hears worse. The operation on the second ear is possible no earlier than six months after the first operation. Unlike the other two types of operations, stapedoplasty fixes the achieved effect for a long time. But the patient needs to know that even this effective type of surgery cannot prevent the development of otosclerosis again and again. If we talk about the most successful conservative method of treatment, then it is a combination therapy using sodium fluoride, preparations containing calcium and vitamin D3.
