The organ of equilibrium
Synonyms
Vestibular apparatus, vestibular organ, vestibular organ, balance ability, coordination of movements, dizziness, balance organ failure
introduction
The human organ of equilibrium is located in the inner ear, in the so-called labyrinth.
Several structures, fluids and sensory fields are involved, which measure rotational and linear accelerations in order to be able to maintain the balance of the body and to enable spatial orientation by maintaining a constant field of vision.
anatomy
The organ of equilibrium is located in the inner ear together with a part of the auditory organ, which is located in a section of the skull, the petrous bone.
These structures are referred to as a labyrinth, whereby a distinction is made between bony and membranous labyrinths. The bony labyrinth are interconnected cavities embedded in the bone. It starts with a forecourt (vestibule), which extends forward into the cochlea (Cochlea, Part of the auditory organ) and backwards into the semicircular canals (part of the organ of equilibrium).
This bony labyrinth contains a water-clear liquid, called a perilymph, in which the membranous labyrinth floats. This follows the structure of the bony labyrinth, so to a certain extent represents its spout. It is also filled with a liquid, the viscous endolymph.
Another division of the labyrinth is that of vestibular and cochlear. The cochlear belongs to the hearing organ, the vestibular, on the other hand, forms the organ of equilibrium and consists of several interconnected parts:
- Sacculus
- utricle
- 3 semicircular canals = Semicircular duct (Ger. = semicircular corridors) à upper, rear and side
The semicircular canals are perpendicular to one another. In relation to the body axes, the upper 45 degrees deviate from the median plane (in a sense the mirror axis of the body running through the head and feet), the rear 45 degrees deviate from the frontal plane and the lateral 30 degrees deviate from the horizontal plane.
The membranous labyrinth contains several sensory fields, so-called sensory epithelia, which are responsible for recording the equilibrium parameters. In Saccule and utricle are these the Macula sacculi as well as the Macula utriculi (Macula = Spot), which are at right angles to each other. In the semicircular canals these are the 3 cristae ampullares (Crista = Bar).
The information that is gained through these sensory fields is passed on to the balance nerves, the vestibular nerve, with the help of the sensory cells, and from it to its nerve nuclei, the vertibular nuclei in the brain stem. From there there are connections to the brain (Postcentral gyrus), to the spinal cord, to other parts of the brain stem, to the cerebellum, to the muscles of the eyes, as well as to other parts of the muscles.
Histology and tissue
The structure of the different sensory epithelia is comparable except for small differences.
There are always sensory cells, the hair cells, and supporting cells in which the hair cells are embedded. Each hair cell has several cell processes, namely a long (Kinozilium), and several short ones (stereocilia). These are connected by a tip on the left, which can be imagined as rope-like structures between the individual cilia (Cilium = Cilia).
Above the hair and supporting cells there is a gelatinous mass, which has a different structure depending on its location.
On the Macules in Saccule and utricle In each case there is a so-called gelatinous statolith membrane, which gets its name from embedded calcium carbonate crystals (= Statoliths) receives. The cell processes of the hair cells protrude into it. However, they are not immersed directly into the membrane, but are still surrounded by a narrow space containing endolymph.
The Cristae the semicircular canals, on the other hand, are covered by the cupula, also a gelatinous mass into which the cell processes protrude.
Both the Macules as well as the Cristae are the hair cells via synaptic connections between the equilibrium organ and the equilibrium nerve (Vestibular nerve) coupled.
The sensory epithelia are surrounded by other epithelium, but have a greater height than this and protrude beyond it.
The liquids in the labyrinth also have a special composition.
The perilymph, which surrounds the membranous labyrinth, contains an aqueous electrolyte-containing liquid that is similar to that of the intercellular spaces (interstitial Fluid) in the body. That is, the sodium content is high, while the potassium content is low. The mechanism of perilymph formation is not exactly understood; the connection with that plays a role Subarachnoid space of the brain, which is located between the brain and the meninges.
The endolymph contained in the membranous labyrinth is also a liquid, which, however, in contrast to the perilymph, contains little sodium and a lot of potassium. The endolymph is produced by structures both in the vestibular labyrinth and in the cochlear labyrinth (Stria vascularis).
The different content of electrolytes (= ions) is important for the stimulation of the sensory cells, which can pass on information to the brain.
Function of the balance organ
The function of our balance organ (vestibular organ) is to keep our body in balance in every position and in every situation so that we can orientate ourselves in space.
This phenomenon is particularly impressive when you are sitting on a very fast moving carousel. Although the body turns against the environment without us moving, our balance organ still helps us not to lose our orientation.Even if a patient turns in a circle, he should then be able to quickly perceive the environment again clearly and without any dizziness or visual disturbances afterwards.
The organ of equilibrium therefore consists of different parts in order to be able to fully fulfill its function. On the one hand there are the three semicircular canals, which, due to their different orientation, can perceive every direction and every rotational movement in our body or in our environment and adjust the body accordingly. On the other hand there are the two macular organs sacculuc and utriculus. These help us to be fully oriented again within a few milliseconds in the case of translational accelerations (for example when you come to a screeching halt in the car), but it is not enough if only our muscles and our brain know that we have just stopped or that we are the world turns around us because we are sitting on a carousel.
Our eyes also need to be informed. Another function of the organ of equilibrium is therefore to pass all information to the eye. In this way, the eye can adapt to the respective situation and carry out a compensatory movement (nystagmus). This can be observed particularly well on the train with the person opposite you: if the person opposite looks out the window, a translational acceleration acts on him because the train is moving. Accordingly, the organ of equilibrium fulfills its function and forwards the information to our eyes. If the other person looks out the window and tries to fix a point, his eyes will always jump back as soon as the landscape has passed.
Ultimately, this process is a functional coupling between the organ of equilibrium and the eyes.
How does dizziness arise from the balance organ?
Dizziness can be caused in a number of different places. The organ of equilibrium perceives the sense of balance and transmits them to the brain via a large nerve.
The cause of dizziness can therefore lie in the equilibrium organ or in the large equilibrium nerve (e.g. vestibular neuritis). Furthermore, different stations of the brain come into question (e.g. vertigo caused by alcohol).
In addition, there can also be a disagreement between what the eye sees and what the balance feels (e.g. carousel driving). The brain cannot classify this correctly and signals dizziness.
The exact cause of the vertigo is sometimes difficult to assess and can therefore usually only be determined by an ENT doctor or a neurologist.
In addition to the inflammation of the equilibrium nerve (vestibular neuritis) mentioned above, so-called “benign paroxysmal positional vertigo” (BPPV) is an even more common cause of persistent or recurring vertigo. There are small crystals (otoliths) in the passages of the organ of equilibrium and influence it with every movement.
How can you train the organ of equilibrium?
Just as you can improve your strength, endurance or dexterity, you can also improve your balance organ through regular training.
The reason for this is the formation of new synapses in the brain, which link the information with one another and thus make it faster and easier to call up. It is important that you adapt the training to your level of training. There are numerous exercises that increase in intensity and difficulty.
So someone with acute inner ear infection and constant dizziness shouldn't do the same exercises as a healthy person. Since the exercises can lead to dizziness, these people would otherwise be very much at risk of falling.
Patients with an equilibrium organ disease should only perform exercises while lying down, also because of their bed rest. For example, you can move your eyes in different directions and get faster and faster.
In another exercise, you can alternately tilt your head back and forth while increasing your speed. This exercise can also be varied by tilting your head from side to side. In addition, there is the possibility to move a finger or pen back and forth in front of your nose and try to follow it with your gaze at all times.
It is important that these exercises are experienced as difficult and that a feeling of dizziness arises. Otherwise, you should switch to more demanding exercises.
Diseases of the organ of equilibrium
Diseases of the vestibular apparatus (organ of equilibrium) are usually characterized by vertigo / vertigo. Examples of common vestibular forms of vertigo are benign paroxysmal positional vertigo, Vestibular neuritis and Meniere's disease.
Benign paroxysmal positional vertigo (benign = benign, paroxysmal = paroxysmal) is a clinical picture of the organ of equilibrium, which is triggered by a change in the position of the body. The reason for this are stones of the Maculeswhich stimulate the sensory cells. This is known as Canalolithiasis. Symptoms of this inadequate irritation are vertigo, nausea, vomiting, pseudo movements of the environment and nystagmus. This form of dizziness is treated by means of storage samples.
Further information can be found under our topic: Positional vertigo
Vestibular neuritis is an inflammation of the equilibrium nerves. This becomes noticeable as permanent vertigo, nausea with vomiting, sham movements, tendency to fall and nystagmus. The therapeutic options are bed rest, immobilization of the head, medication for nausea and dizziness (Antivertiginosa) as well as training of balance.
Please also read our article on this Vertigo training.
The symptoms of Meniere's disease also include vertigo, nausea, vomiting, tendency to fall, nystagmus, as well as tinnitus and inner ear hearing loss. A hydrops of the endolymph in the labyrinth is probably responsible for the symptoms. The whole thing is treated with medication against nausea and vomiting (Antiemetics) as well as betahistine.
How are crystals formed?
This section also refers to the so-called "benign paroxysmal positional vertigo" (BPPV).
This leads to sudden attacks of dizziness due to the small crystals (otoliths or statoliths) contained in the organ of equilibrium. These crystals consist mainly of calcium carbonate and are present in every human being in the organ of equilibrium. Usually, however, these are embedded in a kind of “membrane” and remain there. In the case of positional vertigo, the crystals are likely to detach and shift into the fluid-filled ducts of the organ of equilibrium.
What to do if the organ of equilibrium is inflamed?
If an inflammation of the equilibrium organ or nerve is suspected, for example due to excessive dizziness, nausea and vomiting, an ear, nose and throat doctor should be consulted.
If this confirms the suspicion, several therapeutic measures come into question. First, the doctor will determine the severity and urgency of drug treatment. In any case, rest by strict bed rest is advisable. At the same time, drugs are often given to combat dizziness and nausea (antivertiginous drugs).
In the case of advanced inflammation, drugs from the group of so-called "glucocorticoids", which also include cortisone, are prescribed. These are the method of choice for inflammation of the equilibrium nerve (vestibular neuritis).
In addition to bed rest and drug therapy, another important component is physiotherapy to strengthen the organ of equilibrium and to compensate for the symptoms caused by the brain.
When do you need cortisone?
Cortisone belongs to the group of drugs known as "glucocorticoids". These are often used for inflammation as they suppress the immune system.
This leads to a reduction in symptoms and thus dizziness and nausea. For inflammation of the organ / nerve of equilibrium (vestibular neuritis), glucocorticoids (for example "methylprednisolone") are the drug of choice.
These improve the recovery of the organ of equilibrium and thereby reduce both the acute complaints and any symptoms that may persist afterwards. However, it is important to be certain of the diagnosis as different therapies are used depending on the cause of the vertigo. For example, cortisone only helps with inflammation and not with congenital, degenerative or traumatic defects.
Disorders of the organ of equilibrium
The organ of equilibrium (vestibular organ) is located in the inner ear, more precisely in the cochlea of the inner ear. From here it ensures a coordinated sense of balance with every movement and every position of the body in space.
A disruption of the organ of equilibrium is therefore associated with increased discomfort. Typical signs of a disturbance of the equilibrium organ can be sudden attacks of dizziness, which get worse in certain positions or with certain movements, for example when turning your head.
Many patients complain of sudden attacks of dizziness, especially when falling asleep. This is due to signs of wear and tear in the ear, which ultimately lead to a disturbance in the organ of equilibrium. These are small stones that are deposited in the inner ear and then disrupt the function of the organ of equilibrium.
In addition to dizziness, there are other symptoms that suggest a disorder of the balance organ. On the one hand, many patients complain of recurring nausea. This can be explained by the fact that the brain has to process inaccurate information again and again due to the constant feeling of dizziness. This can lead to discomfort and also increased nausea.
Headaches are also common. This is due to the connection between the balance organ and the eye. Normally the eye always adapts its movements to the position of the body and relies on the information it receives from the organ of equilibrium. If there is a disturbance in the organ of equilibrium, this is always accompanied by incorrect eye movements and can thus lead to headaches due to the constant attempts to compensate. Causes of a disturbance in the organ of equilibrium can on the one hand be signs of age, such as the crystal stones (otholias), which are deposited incorrectly, but it can also be a circulatory disturbance, which means that the inner ear and thus the organ of equilibrium cannot be adequately supplied.
In addition, there are so-called neurotopic viruses, i.e. viruses that spread in the area of the brain, which can temporarily damage the organ of equilibrium and thus lead to disorders. This usually not only results in a disturbance of the organ of equilibrium, but also in a temporary hearing loss or at least in hearing impairment, since the auditory nerve is usually also affected.
Failure of the equilibrium organ
The organ of equilibrium (vestibular organ) is a tiny organ in the cochlea in our inner ear.
This sensory organ receives information about the position in which our body is currently and in which direction we are tilting our head. When we start to spin in circles like crazy or when we turn our head around to shout something to someone, for example, our equilibrium organ has to work particularly quickly and precisely so that we don't lose our balance and fall over.
If there is a failure in our equilibrium organ, there is always dizziness and a certain tendency to fall. It is important to distinguish which part of the equilibrium organ fails. On the one hand, there are the three floor corridors, which are responsible for rotational movements and always monitor in which direction our head and / or our body are currently moving.
On the other hand, there are the two macular organs (sacculus and utriculus), which measure the so-called translational acceleration and gravity at all times. So if we suddenly stop in a car at full speed, these two macular organs ensure quick orientation and the necessary balance.
However, it is possible that after a flu-like infection, for example, the patient becomes more dizzy. This can be caused by a short, one-sided failure of the organ of equilibrium.
Usually the vestibular nerve, i.e. the cranial nerve that forwards the information to the brain, is disturbed by the viruses and therefore no longer forwards the information to the brain.
However, it can also be the case that when the pressure is increased, for example due to an otitis media, the nerve is compressed and can therefore no longer adequately convey the information.
As soon as the balance organ fails, the patient has the feeling that he is sitting in a rapidly rotating carousel. There is a strong vertigo that is often associated with compensatory eye movement (nystagmus). The nystagmus is directed away from the diseased side, which means that in the event of a functional disorder (vestibular neuritis) or a failure of the left balance organ, for example, the eyes compensate to look in the right direction. At the same time, the patient has the feeling that everything is turning to the left and there is an increased tendency to fall to the left.
However, so-called benign (benign paroxysmal) positional vertigo can also occur. In this case it is a question of recurring attacks of vertigo, depending on the position of the patient. In addition, there is often nausea and, in rare cases, vomiting. In this case it is not a question of a complete failure of the equilibrium organ. It is much more a matter of small crystals of calcium carbonate, which are normally located above the organ of equilibrium, but which have now been detached due to trauma (for example a fall in the ear) and therefore supply the organ of equilibrium with incorrect information when positioned in certain positions and therefore irritate it.
As a result, certain positions of the patient lead to sudden but very severe vertigo.
If a patient complains of movement-dependent vertigo, paired with vertigo, then it is usually a bilateral failure of the organ of equilibrium (bilateral vestibulopathy). Mostly it is difficult for the patient to orientate himself, especially in the dark. Since the eyes are often blurred and compensatory movements occur again and again (nystagmus), headaches can also occur. In addition, repeated attacks of dizziness can cause nausea or even vomiting.
The cause of bilateral failure of the vestibular organs is often what is known as Meniere's disease. Hearing loss or ringing in the ears is often added, but it can also lead to an isolated feeling of dizziness.
Since meningitis can also be the trigger for the frequently occurring dizziness, patients should definitely go to the doctor for a neurological check-up. However, it can also be the case that suddenly occurring dizziness is only triggered by an otitis media and disappears on its own with treatment of the disease.
