What may be the cause of sudden deafness?

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Human sound is transmitted along the pathways of the outer ear, middle ear, inner ear, and central nervous system. A "short circuit" in any link on the pathway will lead to deafness. Sudden deafness refers to sensorineural hearing loss that occurs suddenly and unexplained within 72 hours (a hearing loss of at least 20 decibels in two adjacent frequencies).

What is the cause of sudden deafness?

Sudden deafness is a sudden, unexplained sensorineural hearing loss, also known as sudden deafness. Its onset, rapid progression, and treatment effect are directly related to the time of treatment, so it should be regarded as an otological emergency.

It is currently generally speculated that sudden deafness may be related to a very thin artery in the inner ear - the internal auditory artery. The internal auditory artery is a blood vessel that specifically supplies blood to the inner ear. After this artery enters the ear, there is no collateral circulation, just like a branch without branches when it reaches its terminal. Therefore, if the internal auditory artery spasms or thromboembolism occurs, the blood supply to the inner ear will be insufficient or Complete blockage will affect the function of the inner ear, resulting in sudden deafness. Because this artery is very thin, current testing methods, such as CT and MRI, are difficult to detect the exact problem or the location where the blood flow is blocked.

The cause of sudden deafness is unknown. Many pathogenic factors may cause sudden deafness. Currently, the main ones that have been widely recognized include the theory of viral infection, the theory of circulatory disorder, The autoimmune theory and the membranous labyrinth rupture theory, etc.

1. Viral infection
Many viruses may be related to this disease, including cytomegalovirus, mumps virus, rubella virus, measles virus, herpes simplex virus and influenza viruses A, B and Chickenpox virus, etc. Many patients have a history of colds before the onset of the disease. Sudden deafness in children often occurs in winter and spring when upper respiratory tract infections and mumps are popular, and the hearing loss is more severe. Before the onset, there is often a history of exposure to colds or mumps or illness. The medical history suggests that the disease is closely related to viral infection.

2. Circulation disorders
It is generally believed that inner ear blood supply disorder is the main cause of sudden deafness. The degree of hearing loss in patients is related to cochlear blood flow velocity, blood flow and blood vessel cross-sectional area. . The blood supply of the inner ear comes from the labyrinth artery. The physiological activities of the hair cells in the inner ear have high oxygen consumption and poor tolerance to hypoxia. A decrease in blood pressure or partial pressure of circulating carbon dioxide may cause a decrease in the oxygen tension of the cochlear perilymph, thereby reducing the oxygen supply to the inner ear. , causing hearing loss.

3. Trauma.
Sudden hearing loss may occur in major car accidents, head injuries, fights, etc. Some are transient and will heal automatically in a few days; some are delayed onset, with no hearing loss at the beginning and hearing loss occurring after a few days. When this happens, you must treat it promptly and don’t wait a few days to see what happens.

4. Autoimmunity
The autoimmune theory is sudden deafnessNewer pathogenic mechanisms. Epidemiological studies suggest that some autoimmune diseases such as Cogan's syndrome, temporal bone arteritis, systemic lupus erythematosus, polyarteritis nodosa, etc. are related to sudden deafness.

5. Membrane rupture
Membrane rupture refers to the rupture of the round window membrane or vestibular membrane of the inner ear, combined with the rupture of the cochlear membrane. Studies have found that there may be certain defects in the anatomy of the inner ear that lead to rupture of the window membrane in patients with traumatic brain injury, forced coughing, vomiting or sneezing, and barotrauma caused by high flying, diving and swimming, resulting in sudden deafness.

6. Membranous labyrinth hydrops
Some mild or moderate sudden hearing loss, with or without vertigo, may be different types of Meniere's disease. Sudden deafness may also be the first symptom of Meniere's disease, and 5% to 6.6% of patients eventually develop Meniere's disease; 27% (3/11) of patients with sudden deafness have a positive furosemide test. Symptoms such as ringing. Sudden changes in middle ear air pressure and intracranial pressure occur due to sudden exertion or drastic changes in air pressure, which can induce sudden onset.

7. Life and work are stressful. Long-term mental tension and lack of relaxation may lead to sudden deafness.

8. Others

Regarding the pathogenesis of sudden deafness, there are also theories such as metabolic disorders, inner ear edema, allergies, stria vascularis dysfunction, etc., which have yet to be verified. . Clinically, most patients have no obvious cause of the disease, and some have obvious fatigue, emotional agitation, mental stress and a history of colds. These factors may have a certain relationship with the disease.

The treatment of sudden deafness must be prompt and timely. The earlier the treatment, the better the effect. Among them, the low-frequency descending type has the best therapeutic effect, followed by the high-frequency type, and the flat type and total deafness type have the worst effects. Treatment mainly involves the use of drugs that improve microcirculation, glucocorticoids, which can be intravenously infused, taken orally, or injected into the tympanic membrane and around the ears, and drugs that reduce blood viscosity. If the effect is not good, neurotrophic drugs, etc. can be used in the later stage. While taking active treatment, you should also maintain an optimistic attitude.