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Dizziness and balance problems
A guide for patients and carers
How does the balance system work?
It is often said that the sense of balance comes from the balance organs located in the inner ear. This is largely true and indeed most cases of dizziness and vertigo are due to problems in these balance organs. The ear has three main components: the external, or outer ear, which is the only part that can be seen from the outside; the middle ear, whose main function is to transmit the sound from the outer to the inner ear; and the labyrinth, or inner ear. The labyrinth is 4 located deep inside some of the hardest bones in our skull. It is divided into the cochlear organ, which is responsible for hearing, and the vestibular organ, which is responsible for balance. This close link between the hearing and balance organs in the ear is the reason why your doctor will ask you what your hearing is like.
The vestibular, or balance, organs inform the brain about the movements and position of your head. There are three sets of tubes or semi-circular canals in each vestibular organ, and these detect when you move your head around. There are also two structures called the “otoliths”, which inform the brain when the head is moving in a straight line and indicate the position of the head with respect to the pull of gravity. Dizziness or vertigo occurs when the right and left balance organs do not work together (in symmetry), because this makes your brain think that your head is moving or turning when it is not. This also explains why many forms of dizziness are either triggered or increased by movements of the head. However, it is important to bear in mind that the maintenance of balance is a complex function and that while the ear is a very important component of the system, it is not the only one.
In order to have a good sense of balance we need to be able to see where we are and be aware of the position of certain key parts of our body in relation to the other parts and to the world around us. The brain has to know how the feet and legs are positioned with respect to the ground and how the head is positioned with respect to our chest and shoulders. This information is conveyed to the brain by detectors of position and movement located in our muscles, tendons and joints, particularly in the neck, ankles, legs and hips. A crucial aspect of the efficiency of the balance system is that our brain can control balance by using the information that is best suited at any particular point in time. For instance, in the dark, when the information conveyed by our eyes is reduced or unreliable, our brain will use more information from our lower limbs and our inner ear. If, on the other hand, we are walking on a sandy beach during the day, the information coming from our legs and feet will be less reliable and we will tend to use our vision and vestibular organs more.
We almost never have to rely solely on the information provided by the balance organs of the ear, and that is why even people who have lost the function of both inner ears do not entirely lose their sense of balance. So while dizziness and imbalance usually arise from disorders of the inner ear, because of the complementary support provided by the eyes and the detectors of movement located in our joints and muscles, most people usually regain a good sense of balance. Problems with the nerves carrying the impulses from the balance organs to the brain or problems in the balance centres of the brain can also cause dizziness, but these are less common.
In order to have a good sense of balance we need to be able to see where we are and be aware of the position of certain key parts of our body in relation to the other parts and to the world around us. The brain has to know how the feet and legs are positioned with respect to the ground and how the head is positioned with respect to our chest and shoulders. This information is conveyed to the brain by detectors of position and movement located in our muscles, tendons and joints, particularly in the neck, ankles, legs and hips. A crucial aspect of the efficiency of the balance system is that our brain can control balance by using the information that is best suited at any particular point in time. For instance, in the dark, when the information conveyed by our eyes is reduced or unreliable, our brain will use more information from our lower limbs and our inner ear. If, on the other hand, we are walking on a sandy beach during the day, the information coming from our legs and feet will be less reliable and we will tend to use our vision and vestibular organs more.
We almost never have to rely solely on the information provided by the balance organs of the ear, and that is why even people who have lost the function of both inner ears do not entirely lose their sense of balance. So while dizziness and imbalance usually arise from disorders of the inner ear, because of the complementary support provided by the eyes and the detectors of movement located in our joints and muscles, most people usually regain a good sense of balance. Problems with the nerves carrying the impulses from the balance organs to the brain or problems in the balance centres of the brain can also cause dizziness, but these are less common.
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