British Tinnitus Association

V.Jayarajan FRCS, Msc - Consultant Audiological Physician

Background
The ability to stand and walk upright is something quite unique to humans. It is also a function that develops gradually. We all know that toddlers first lift themselves up to crawl, and usually by about 12 to 18 months they can stand and walk unaided.

When a child assumes the upright position, the brain has to adjust to this by perceiving imaginary horizontal and vertical planes. At this stage the child will have frequent falls while the brain is adjusting to the change in posture. This process requires inputs from different sensory systems. These are: the musculoskeletal system (proprioception), vision, and the balance organs in the internal ears. These inputs are received by a centre at the base of the brain – the vestibular nucleus. This in turn has links to a nearby organ – the cerebellum. The cerebellum has the role of coordinating posture and balance.

The Sensory Systems
Let us now look at all the sensory systems which are responsible for balance.

a) Proprioception
The muscles, bones and joints have sensory nerves which send messages about muscle activity and the movement of limbs. In this respect the most important joints are those which are involved in weight bearing. These are the ankles, knees, hips and the spine, together with the muscles attached to these areas. The ankles regulate minor swaying movements while the knees and hips control larger sway of the body. The muscles of the spine have the function of maintaining the curvature of the spine, preventing the individual from leaning too far forward or backwards. They also tend to keep the head upright, so that the eyes can focus on objects in different planes.

b) Vision
The eyes also play an important part in our balance by providing vital information about the environment, by working closely with the balance organs. This is achieved in several ways. We are able to keep our gaze fixed on an object during head movements, and also when we are moving. When we need to look at different objects, we can shift our gaze between objects, and are also able to follow moving objects even when we are in motion. All this can take place without causing a disturbance in balance, due to coordination of activity between the eyes and balance organs. In addition, fixing one’s gaze on an object will suppress the sensation of dizziness which occurs when there is a disorder of the balance organs.

c) The Balance Organs
The third sensory system that is responsible for the control of balance are the balance organs in the ears. These organs are located in the internal ears, and provide vital information about the body’s position in space. One part of each organ provides information about angular movement, such as body tilt, while another section detects changes in linear movement. The organs in the two ears are the mirror images of each other, and send information to the brain (vestibular nucleus).

What are the likely causes of a balance disorder?
The commonest reason for a balance disturbance is a disorder of the balance organs. However, it is important to realize that these symptoms could also occur in people who have diseases which affect their vision or proprioception. Furthermore, dizziness may be a manifestation of medical conditions such as anaemia, or when there is a sudden change of blood pressure.

First, let us look at actual damage to the balance organs. This could take one of two forms. The organ may slow increased activity (an ‘irritative’ lesion). In these cases patients often have severe nausea and may even vomit. Due to increased activity of the organ there is a sensation of spinning to the same side. This may even result in falls to this side. However, the damage may have the opposite effect, namely reduced function of the organ (a ‘paralytic’ lesion). In this case, the opposite organ’s activity predominates, and the spinning and falling is to the side opposite to the site of damage.

A third type of disorder is when there is a fluctuation of function of the balance organs. This may also affect the hearing organ, leading to intermittent attacks of dizziness, nausea, vomiting, hearing loss and tinnitus. These attacks may last up to 24 hours. The dizziness, nausea and vomiting are often so severe that patients require bed rest and even admission to hospital. There is then a gradual recovery of balance function. This process could take several days. However, further attacks could occur during this recovery phase, and this may prolong the recovery process. The initial attack is caused by increased activity of the balance organ. Hence the feeling of spinning is to the same side. After this, there is some residual damage of the organ. Hence during recovery there is a tendency to spin and fall to the opposite side.

In other subjects dizziness and sometimes nausea can be provoked by head movements. Symptoms commonly occur during bending, looking up, extending the head or turning in bed. This condition occurs due to misplacement of crystals in the balance organ during these movements. The symptoms usually last a few seconds, but can sometime go on for about a minute.

This disorder is not uncommon, and is usually due to movement of crystals in one of the balance organs. Rarely, both organs may be affected together, or at different times. Often no treatment is necessary, because the condition resolves spontaneously. However if it persists, a simple manoeuvre could be performed or certain exercises could be prescribed.

Dizziness may also be caused by disorders of the pathways of balance within the brain. This frequently occurs in subjects whose blood circulation is compromised. Unlike conditions affecting the balance organs, here the feeling of imbalance is more or less constant. People often describe the dizziness as a feeling of ‘wooziness’ There is little or no nausea, and the condition does not respond to ‘anti sickness’ medication.

In many people the sensation of dizziness causes a feeling of anxiety. Indeed, anxiety itself may be the reason for a patient’s dizziness. There is also a tendency to avoid the positions or actions which provoke the symptoms. Patients also tend to shut their eyes, in the hope that by doing so the dizziness would subside. Unfortunately all these factors in fact lead to an aggravation, rather than a relief of the problem. Avoidance of dizziness provoking positions prevents the natural recovery process due to reduced stimulation of the balance pathways, while eye closure prevents suppression of the mechanisms which inhibit the dizziness.

The role of other sensory systems
If the dizziness is caused by a disorder of either the balance organs or the balance pathways, the body will depend on the eyes and the sensors in the muscles and joints to maintain balance. In some cases, these systems may also be affected by diseases such as diabetes and arthritis. It then become quite difficult for the body to maintain its balance. These patients have a significant risk of falling.

What can be done to improve balance?
In most cases, there will be a gradual recovery of balance function. This process will be prolonged if there is marked anxiety or a lack of mobility. It has been shown that simple provocation exercises are the best treatment for patients with disorders of the balance organs and balance pathways. They should also be encouraged to keep active. This could take various forms, such as gardening, going for walks or playing sports which require good hand – eye coordination, such as tennis or badminton. Anxiety can often be relieved by a clear explanation about the underlying condition. Relaxation Therapy could also be helpful in treating anxiety. This could be carried out on its own, or may be practiced as a part of techniques such as Yoga, Pilates or Tai Chi.

Reviewed June 2009 - © British Tinnitus Association

This information is not a substitute for medical advice. You should always see your GP / medical professional.