Otosclerosis is an impairment of sound transmission to the inner ear caused by remodelling of components of the auditory organ, most commonly the stirrup and the oval window, but other ossicles may be affected. The causes are not fully understood. The greatest influence on remodelling of components involved in sound conduction is thought to be endocrine disruption, viral infections and toxic substances.
Table of contents:
- Otosclerosis - what is behind the term?
- How does it manifest itself?
- ENT - diagnosis and treatment
- Treatment
- When to see a doctor?
Otosclerosis - what is behind the term?
Otosclerosis is described as a progressive dysplasia (change in the nature of the tissue) with destruction, remodelling and ossification of the areola of the vagus - the component of the inner ear responsible for the sense of hearing and balance. The remodelling is multistage and may have different triggering causes. The most common factors influencing the development of osteosclerosis include viral infections, autoimmune processes, mechanical trauma, metabolic disorders (e.g. diabetes), hormonal, toxic (drugs, smoking, alcohol) and vascular (disorders of the blood supply to the auditory organ). In addition, the process can also occur in people with a genetic predisposition, but can also start without an external factor. Regardless of the triggering inducer, the essence of the process is the destruction of the healthy bone that makes up the components of the auditory organ, which most often leads to the immobilisation of the stirrup (one of the ossicles) in the oval window, a structure involved in the conduction of sound to the inner ear, from which the stimulus is then transmitted to the higher levels of the auditory organ - the nervous system.
How does it manifest itself?
Otosclerosis manifests itself by progressive hearing loss and persistent tinnitus of a hissing, buzzing nature. Usually the hearing loss is bilateral, but not equally severe. It most often appears between the ages of 15 and 40. Unfortunately, the disease can lead to profound hearing loss, while the course of the process is many years. The most important diagnostic issue is a thorough history, which includes the entire history of lesion progression. Usually, the nature of the changes is linear and slow, presided over by a progressive impairment of sound perception. Pregnancy and lactation can accelerate and aggravate the changes. Factors influencing the progression of the process in women may also include oestrogen agents. The clinical picture may additionally include balance disorders and dizziness.
Laryngologist - diagnosis and treatment
In the case of progressive hearing loss accompanied by tinnitus, dizziness and balance disorders, the specialist to visit first is an ENT specialist. During the visit, he or she will perform an otoscopic examination, which will be preceded by a thorough clinical history. This examination consists of looking at the external ear canal using a special device with a light source inside (otoscope). The examination is not painful and allows, among other things, an assessment of the tympanic membrane, which in the case of otosclerosis is wall-shaped and translucent, the so-called Schwarz sign. In addition, tonal and verbal audiometry is performed.
Hearing test, photo: panthermedia
The former assesses the hearing threshold to determine the type and degree of hearing impairment. The second complements the first and assesses the person's understanding of speech. In tonal audiometry, otosclerosis is characterised by a reduction in hearing threshold of about 10-20 dB at 2 kHz. As the disease progresses and the inner ear is damaged, the threshold curves align horizontally or fall in high frequencies. Reed tests - the Rinny and Weber tests - play an important role in the ENT examination. These tests are designed to assess the conduction and reception of acoustic waves.
Treatment
Causal treatment in otosclerosis is unfortunately not possible. Pharmacological treatment can act as an auxiliary and only slow down the disease process. The most effective treatment is surgery. The indication for surgery is an increase in the air conduction threshold of 30 dB. For those who do not qualify or choose not to undergo surgery, sodium fluoride treatment and hearing aids may be offered. Stirrup surgery is highly specialised and based primarily on microsurgery using a microscope. This type of surgery is made possible by the enormous development of techniques, microsurgery, prostheses and laser systems. The main surgical method is stapedectomy, which involves making a small hole in the stirrup (one of the ossicles of the ear) and placing a microprosthesis in it. This procedure can even be performed under local anaesthetic. This allows continuous contact with the patient, monitoring of hearing improvement and observation of any irritation of the inner ear structures. It is important to realise that the procedure involves an extremely small surgical field and the surgeon works with a microscope. These operations are categorised as so-called minimal invasive high successsurgery techniques. The development of ear microsurgery has been a great step in the treatment of this type of condition, but they are nevertheless not without postoperative risks. The most serious, yet rarest, complication is damage to the vagus and total deafness. Others include balance disorders, tinnitus or dizziness. The number of complications decreases with the experience of the centre performing such procedures. The qualification for surgery is not obvious either; certain circumstances may prevent surgery. One of the contraindications is Meniere's disease, permanent balance disorders, active otitis media and perforation of the eardrum. Pharmacological treatment is of limited use, only allowing the progression of the disease to be halted.
When to see a doctor?
Otosclerosis can follow a similar course to several ENT conditions. Nevertheless, certain symptoms may suggest its suspicion. Most often, the course is slow and long and involves a gradual loss of hearing, usually in people before the age of 40. In many cases, pregnancy can accelerate the progression and exacerbate symptoms, in which case patients often see a doctor. Tinnitus may be the first noticeable and life-limiting symptom.
Hearing disorders are often accompanied by dizziness and imbalance. In these cases, it is worth consulting an ENT specialist who, in addition to a basic ENT examination, will refer for audiometric hearing tests.