The main cause of decreased hearing by a sudden loss of hearing is suspected in a circulatory disorder of the blood in the inner ear with concomitant minor supply of hair cells. The hair cells represent the sensory cells of the inner ear, which are responsible for the conversion of the sound stimulus into an electrical stimulus.
The hair cells then transmit the impulses via the auditory nerve to the brain, where the sound and the sound can then be perceived as being. In order to maintain the function of the hair cells, it is essential that these cells are supplied with blood and thus with oxygen. If there is a blood circulation disorder in the inner ear area, the loss of function will result in the described hearing impairment.
The reasons for this circulatory disorder have not been established, but there are many causes of blood supply to the inner ear. To name:
If the blood changes its flow habits ( viscosity ), coagulation in the blood vessel with concomitant closure ( embolism ) of the vessel can occur more quickly. The condition is that the flow rate of the blood is reduced. This happens when the blood thickens, which is the case, for example, with reduced daily fluid intake. Particularly at risk are older people. Coagulation disorders of the blood can lead to premature blood clotting and thus cause a vascular occlusion. It is believed that the hearing loss is a minor stroke or infarction of the inner ear. The causes correspond approximately to those of myocardial infarction or major stroke. Patients who suffer from the typical symptoms of stroke (dizziness, possibly headache, paralysis, etc.) often have reduced hearing on one or both ears. It is assumed here that in addition to the blood clot, which clogged a vessel of the brain, even a small clot misplaced the vessel of the inner ear. The atherosclerosis causing arteriosclerosis, so the thickening of the vessel wall by fats and non-degradable glycerides, is held responsible for the cause of an acute hearing loss. This can occur with a permanently high cholesterol, lack of exercise, obesity or diabetes mellitus.
Noise can also be a possible cause of a hearing loss. However, the underlying mechanisms are not yet fully understood.
One explanatory approach is the direct effect of noise on the inner ear. In order to be able to hear, hair cells in the inner ear have to be deflected differently depending on the pitch and volume. Figuratively, this can be imagined by a lawn on which the blades of grass are deflected by the wind. If the hair cells are constantly deflected by noise, their metabolism increases and they need more nutrients and oxygen. If the noise persists for a longer period of time without a break for regeneration, the metabolism eventually exhausted and the hair cells can no longer be adequately supplied. The result is the irreparable sinking of hair cells. With the progressive decline finally the hearing performance decreases.
Another explanatory approach emphasizes the psychological burden of noise. If the victim can not escape the noise, he feels it as stress. It automatically relaxes and reactively releases hormones that lead to increased blood pressure through constriction of blood vessels. Normally, this reaction from the body makes a lot of sense, because stress requires a willingness to act. However, if the blood pressure rises too much, blood circulation may be impaired in some cases. One possibility is that the vessels leading to the inner ear are narrowed too much. The result is a shortage of the inner ear, which manifests itself in an ear noise or a hearing loss. If this condition lasts too long, it can lead to a sudden loss of hearing with a further symptom severity.
Although there is no evidence, the stress factor is repeatedly blamed for an acute hearing loss. This is probably due to the fact that hearing loss often occurs in patients who are either in an acute stressful situation or who suffer from a chronic stress situation. One explanatory approach is a high adrenaline release during a stressful situation. Adrenaline has the task to increase the blood pressure accordingly (see also: hypertension). This is done by a constriction of the blood vessels. If the vessels narrow too much and reduce their diameter, it can also lead to a blood supply of the hair cells of the inner ear (similar effect of the heart attack).
An inner ear or a hair cell damage can always be caused by injuries and trauma. It is therefore particularly important to ask the patient about recent falls or accidents.
It can also happen that infections cause a hearing loss. Otherwise, these infections can be unremarkable and only noticeable on the inner ear. The diagnosis proves to be difficult for this reason. Pathogens can be mumps viruses, herpes viruses, HIV or adenoviruses. The doctor should therefore ask the patient for any causative research for concomitant disease at the moment and the weeks and months before.
Middle ear inflammation ( ottitis media ) can also cause a sudden hearing loss. Reason here is an inflammatory accumulation of fluid in the inner ear, which hinders the transmission of sound from outside to inside.
A cold can simulate a sudden loss of hearing. As a rule, however, there is no malfunction of the inner ear. Only the symptoms of these mutually independent diseases can overlap. Both diseases can lead to a feeling of pressure in the ear, dizziness and a deafness.
In contrast to the acute hearing loss, there is no circulatory disturbance in the inner ear. Rather, it is the inflammatory swollen mucous membrane in the throat area, which leads to a ventilation disorder of the middle ear. This in turn manifests itself in a feeling of pressure in the ear and a hearing loss. The dizziness in a cold is not caused by a functional impairment of the equilibrium organ in the inner ear, but by the usually filled with secret sinus, which exert a strong pressure on the skull structures.
In principle, all vessel-laying situations can trigger a hearing loss. One must not forget also holding and growth damages of the spinal column, particularly the cervical spine, which can push off by appropriate bending, vessels, which supply the ear with blood and oxygen.
Disorders of the cervical spine itself can in turn have different causes. One possibility would be muscular tension in the neck and neck area, which affect the supply structure pulling from the back towards the ear. Hardened muscle can press on blood vessels or nerves and thus manipulate the supply to the inner ear, which can manifest itself symptomatically in a hearing loss.
A direct injury to the inner ear due to muscle tension is unlikely, but conceivable through a whiplash injury. A rotation of the cervical spine in the context of an accident can thus be another possible cause.
If there is no acute accident and bony changes can still be detected, the age-related wear is seen as a possibility for narrowing of blood vessels or nerve cords in the direction of the ear. For the treating physician, the description and posture of the patient is usually decisive, so that he examines the cervical spine as a possible cause of a sudden hearing loss. If the patient reports a one-sided auditory noise and shows an abnormal posture or muscling of the cervical region, in most cases the cervical spine is quickly revealed as the cause.
In principle, all autoimmune diseases affecting the vessels in the body can also cause a sudden loss of hearing. Again, typical accompanying signs of the patient's sudden hearing loss should be inquired. For example, a patient suffering from temporal arteritis usually complains of severe throbbing headache. Diagnosis is made by blood testing and identification of autoantibodies found in the blood in such a case.
The possibility of a tumor in the auditory nerve as a cause of hearing loss must always be considered. Although this cause of an acute hearing loss is quite rare, it should not be forgotten. In the case of a tumor disease, the so-called acoustic neuroma is described as the most common cause of hearing loss tumor. The diagnostic tool of choice here is the magnetic resonance imaging (MRI) of the head.
At times it can happen that major neurological disorders can trigger the symptoms of a hearing loss. In addition to the stroke described above should also be mentioned the multiple sclerosis (MS) and meningitis (meningitis).
In many cases, behind the sudden hearing loss on one side, there is also only ear contamination due to increased lard production or improper cleaning by cotton swabs ( earwax plug is pushed into the ear canal ).
In most cases, a sudden loss of hearing leads to a complete recovery. Only very rarely does a hearing loss or an ear noise persist. However, the risk of permanent damage increases with the number of auditory cancers that have passed through, as hair cells break with every sudden hearing loss.
Hair cells are essential to our hearing, so their diminishing numbers explain the symptom enhancement. Simply put, this means that the worse you hear, the more hair cells you hear. A new disease is favored mainly by stress and cardiovascular diseases, which can affect the circulation in the inner ear.