Tinnitus is the perception of noises in the ear which correspond to no acoustic signal in the environment. The buzzing, ringing, tinnitus is the perception by the individual of noises or sounds which do not come from the outside, but are produced by the patient himself/herself.

Tinnitus corresponds to the buzzing or hissing sounds heard in one or two ears, or in the head, in the absence of any sound source in the surrounding environment.

The sounds heard can be various natures: low tone pure sounds (buzzing), high-pitched (hissing), continuous or pulsatile, etc.... However, the sounds perceived by the subject are mostly complex and can be similar, for example, to the sound of a bell, hissing, a steam noise, an engine, a grating, a cicada/cricket sound.

The tinnitus is not strictly speaking an auditory hallucination (AH). It can be distinguished from AH by the rudimentary contents of the noises heard (pure sounds or more or less wide-band frequency noises devoid of sense or direction) and by the fact that the patient is aware that they originate from his/her own body.

It results from the production of an abnormal neural signal at a particular level of the auditory pathways which, after being processed by such pathways, is interpreted as a noise when it reaches the auditory cortex.



Given that there is no external source of noise, the sound received is an auditory hallucination created by a reorganization at the level of the cerebral cortex following the loss of auditory acuteness in the frequency of the tinnitus. That is why people who suffer from tinnitus avoid speaking about it too much for fear of being taken for hallucinating persons!

The persons who suffer from it hear a ghost noise produced by the part of the brain which is not stimulated by the usual noises at frequencies which one does not hear any more, given the loss of auditory acuteness in the zone corresponding to the frequencies of the tinnitus.

Regarding the origin of tinnitus, the theory that is most widely recognized is the existence of an external hair cell lesion. In particular, an alteration in the stereohairs attached to the external hair cells would induce the uncoupling of the tectorial membrane. This would lead to a hyperexcitability of the auditory nerve because of the excessive release of glutamate, which would be at the origin of the perceived sounds. A sound trauma can therefore lead to a lesion of the IHC which is visible with the use of electronic microscopy.

MRI Scan showing Tinnitus

MRI (Magnetic resonance imaging) shows clearly this abnormality (see the illustration). Currently, it is well-established that chronic tinnitus is associated with an increase in the activity of the temporo-parietal cerebral cortex.

There are two forms of tinnitus:

THE CAUSES:

Click on the photo to enlarge.

Some of the causes are well known and some others unclear. It is about a symptom and not about a pathology with diverse sources. The causes can be associated with various affections: disorders of the external ear, of the middle ear and\or the internal ear, Meniere syndrome, acoustic neuroma, cranial trauma, high blood pressure, endocrine disorders, etc.

Tinnitus Has Diverse Origins

At the level of the Hearing System: the presence of earwax attached to the eardrum, presbyacousis, otospongiose, Meniere disease, acoustic neurinome, chroni otitis, cholesteatome, abrupt deafness, fracture of the rock;

It appears essentially in the second part of life, after 60 years. Indeed, it often accompanies the hearing loss on high frequencies related to aging ( presbyacousis ), but also the hearing loss related to exposure to noise of professional origin (toleries, boilermaking, tailings(spinnings), orchestras) or during leisure activities (hunting, shooting (firing), concerts and orchestrate rock, mp3 players). The misuse of personal stereos and the non compliance with the legislation concerning the sound levels in theaters (cinemas, concert halls, discotheques) are at the origin of the development of a premature aging of the hearing system.

At the Vascular Level: vascular problems (reduced bloodflow, modified blood crase) are often incriminated as far as they can intervene at every level of the peripheral and\or central auditory pathway, without underestimating its implication on the nervous system in general.

At the Metabolic Level: health problems such as diabetes, high blood pressure, high cholesterol level, high uric acid... oestrogen-progesterone hormonal disorders, thyroid disorders.

Certain medications may cause tinnitus in certain individuals.

Ototoxic medications: certain antibiotics (especially those of the class of aminosides administered intravenously for treatment of systematic or generalized infections), diuretics, anti-paludism medicines (against malaria), anti-cancerous medications and certain analgesics (salicylates such as aspirin) indicate in their product description the risk of toxicity for the ear as a side effect.

Nutrition can also have an incidence on tinnitus, for instance: excessive consumption of caffeine, alcohol, drugs, spicy products, etc.

We shall also note that the psychological factors (stress, anxiety, disturbing emotional event, depression) can influence, stress, or even reveal tinnitus. The disturbance caused by the tinnitus is not necessarily related to its intensity but rather to the perception felt by the individual towards this unwanted and sometimes so tenacious noise.

Neuropsychology teaches us that stimulus sounds that are new or associated with a negative experience are treated as significant sounds and evoke an emotional response which prepares the body for a reaction of flight or confrontation. The repetition of these sounds is translated by an intensification of their perception and a resistance to their suppression by other stimuli.

In contrast, the repetition of neutral signals is accompanied with the progressive fading of the induced responses, which corresponds to the phenomenon of habituation.

The outcome of a tinnitus devoid of emotional meaning for the subject is thus the habituation

Hyperacousis is a dysfunction of the hearing of the internal organ which perceives this sound. The individual has no finer hearing, but perceives noises much more hardly, which sometimes forces such patients to isolate themselves to avoid the noise.

It is a rare affection. The affected persons have perfectly normal hearing, but their level of tolerance to sounds is reduced for certain sounds or sound levels which are not nevertheless recognized by the others as specially strong or unpleasant. The exposure to these sounds causes pain or tinnitusto the hyperacousic individuals, and they can be unbearable and last more or less for a long time. In contrast to a common thinking, if a hyperacousic person is forced to expose himself/herself to the sound that make him/her suffer, instead of protecting himself/herself from it, his/her hyperacousis aggravates. Some extreme cases exist.

Balance Disorders

One-sided or bilateral vestibular dysfunctions, Meniere disease, gentamicine-induced ototoxicity, vestibular neuronite or the labirynthitis are part of the causes of balance disorders.

Balance disorder or what we call the "cerebellar syndrome" is so caused by a damage to the cerebellum or to parts that also contribute to the control of balance such as the internal ear. Several factors allow the detection of a balance disorder.

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