Worldwide, millions of people suffer from tinnitus. The subjective and objective causes can be very different and differ from person to person. In general, tinnitus can occur in connection with a variety of diseases of the ear and the auditory pathway.
Subjective and Objective Tinnitus
With regard to specific causes of tinnitus, a distinction is made between two types of tinnitus when diagnosing: A tinnitus that originates from an actual sound source in the body (e.g. flow noises in blood vessels), and a tinnitus that has no sound source in the body as the cause can be. If such a sound source can be identified within the body, it is called objective tinnitus, otherwise it is called subjective tinnitus.
The majority of those affected (more than 99%) have subjective tinnitus, while objective tinnitus occurs very rarely. The perception of a subjective tinnitus does not arise in the ear itself, but rather through abnormal activity of nerve cells in the brain. An ENT doctor can determine which tinnitus it is exactly (subjective or objective).
Overview of the Causes of Tinnitus
Find out in detail below about possible causes of tinnitus and learn which processes, according to the latest scientific findings, lead to the perception of subjective tinnitus, and what role the emotional and cognitive evaluation play with regard to tinnitus.
Possible causes of subjective tinnitus:
- Sudden hearing loss
- Age-related hearing loss
- Sound trauma (noise trauma, pop trauma, explosion trauma)
- Foreign body in the ear canal
- Inflammation of the ear
- Viral and bacterial infections
- Acoustic neuroma
- Meniere’s disease
- Chronic otitis media
- Cardiovascular diseases
- Central nervous system disease
- Decompression sickness
- Metabolic and kidney diseases
- Endolymphatic fluctuations
- Autoimmune diseases of the inner ear
- Functional disorders of the temporomandibular joint or the cervical spine
- Muscular causes
Possible causes of objective tinnitus:
- Hemangiomas (blood sponges)
- Vascular malformations
- Soft palate nystagmus
- Tubal dysfunction
- Change in the bloodstream of the neck veins
- Tumors in the middle ear
New Knowledge About the Development of Tinnitus
For a long time science assumed that subjective tinnitus developed in the inner ear. However, this assumption has been refuted by the fact that tinnitus usually persists even after the auditory nerve is severed.
With the help of imaging methods, it was also possible to determine that the neural activity in tinnitus patients has changed in different areas of the brain. In principle, the healthy balance between inhibitory and excitatory processes in the auditory networks of the brain is disturbed: In the brain centers involved, there is increased activation and synchronized firing of the nerve cells without an actual sound source being present.
In this respect, there are parallels to phantom perceptions and pain in subjective tinnitus: abnormal neuronal activity occurs in the brain, although there is no corresponding stimulus as a trigger.
Accordingly, although tinnitus is triggered in most cases by hearing impairment, the cause leading to the perception of tinnitus is located in the brain.
Which Processes in the Brain Lead to the Perception of Noises in the Ears?
The sensory cells of the inner ear are arranged tonotopically. This means that the cells that are anatomically located at the beginning of the cochlea are responsible for perceiving high frequencies. Those cells that are further at the end of the cochlea use lower frequencies. This arrangement can be symbolized with the keyboard of a piano: At one end are the low notes, at the other the high notes.
If the sensory cells of the inner ear are damaged, the hearing ability deteriorates in the frequency ranges for which the damaged sensory cells are responsible. In the affected frequency ranges, weaker signals are passed on from the inner ear to the primary auditory cortex.
The tonotopic structure continues in the entire auditory pathway up to the primary auditory cortex. The nerve cells in the primary auditory cortex responsible for the frequency ranges concerned now receive unusually weak signals. The brain then adapts to the new circumstances and reorganizes the connections between the affected nerve cells (reorganization).
Incorrect Subjective Tinnitus Results
Affected nerve cells change their connections to neighboring cells in an unfavorable way, so that normal signal processing is disrupted. This can lead to chronic overactivity and synchronized firing of the affected nerve cells, which then becomes noticeable as tinnitus.
Psychological Consequences of Tinnitus
In tinnitus, the emotional assessment of the noise in the ear plays a major role. Stress, restlessness or even fears can promote the development of tinnitus or increase the perception of noises.
Tinnitus patients often have psychological problems to a high degree as a result of ringing in their ears: sleep disorders, concentration disorders and depressive syndromes are the most common. The global extent to which a patient is affected by their tinnitus can be recorded using psychological questionnaires and quantified in terms of tinnitus severity.
Last but not least, the fact that Tinnitus is an “invisible ailment” sometimes makes it difficult for those affected to find understanding in others for their burden.
Tinnitus patients often report a current psychological stress situation (permanent stress, burnout) when tinnitus first appeared. In addition, stress has an intensifying effect on their subjective burden as the disease progresses. One to five percent of the total population develop serious psychosocial difficulties during the course of the disease due to tinnitus.
Tinnitus can therefore have a negative impact on all areas of life for those affected and lead to serious, undoubtedly disease-related problems in coping with everyday life, which can range from concentration disorders to problems falling asleep and staying asleep to incapacity for work.
As a result of tinnitus, those affected sometimes withdraw from society: the noise in the ear makes it difficult for those affected to relax, so that they react more irritably in social situations without actually wanting to. Even the noise alone – without considering the psychological consequences – can also make communication with others difficult.
The ringing in the ears or the frequent hearing loss make it difficult for those affected to take part in conversations. These circumstances can prevent patients from finding the necessary support in their environment or from establishing social contacts that can also have a stabilizing function for the patient.
Not only can tinnitus be a symptom of another disease itself, it can also cause many different symptoms. Find out more about possible tinnitus symptoms and what treatment options are available here.
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