Smooth body movement and balance are taken for granted. Thus, most people have no difficulty walking on beach sand, on an uneven gravel path, or getting up at night in the dark. However, if there is damage to the body’s balance system, such activities can be particularly tiring or even dangerous. Instability can also be accompanied by dizziness, vertigo, vision and hearing problems, difficulty concentrating and memory impairment.
What is balance?
Body balance is the ability to maintain your centre of gravity within your base of support, preventing falls and ensuring stability. It’s a complex process that involves multiple systems working together. These include the visual, vestibular (inner ear), and proprioceptive (sensory nerves) systems. When the balance system is functioning properly, it allows a person to:
- orient themselves correctly in relation to gravity,
- see clearly in motion,
- easily determine the direction and speed of movement, and
- make automatic corrections to the body’s posture in order to maintain balance, in various conditions and activities.
Balance and movement
Balance and Movement
A complex set of sensorimotor data achieves and maintains balance through vision (optics), touch (proprioception), and the vestibular system (motion, posture, spatial orientation). Accordingly, this information is integrated, analyzed, and leads to adaptive movements of the eyes and body. Medications, injuries, diseases, and aging can affect one or more of the above systems. Furthermore, psychological factors may also affect balance.
Sensory information:
- Visual stimuli: Light is detected by rods and cones (sensory receptors of the retina) and converted to visual signals in the brain. These signals help orient the individual in relation to other objects in the visual environment.
- Muscle, tendon and joint stimuli: Sensory receptors from the legs, arms and other parts of the body send nerve signals to the brain, in order to determine the position of the body in space.
Of particular importance are sensory stimuli that come from:
- the cervix (neck) that indicate the direction in which the head is turning, and from
- the ankles that provide information about the movement of the body in relation to the surface on which it is standing, as well as the quality of the surface (hard, soft, slippery or uneven).
- Vestibular system inputs: Sensory information about posture, movement, and spatial orientation is provided by the vestibular system. When the sensory organs on both sides are functioning normally, the inputs they send to the brain are symmetrical.
Processing conflicting sensory inputs
The human balance system includes a complex set of sensorimotor control systems.
When sensory input from different sources is conflicting, i.e., when one of these subsystems is damaged, disorientation occurs. The result will be balance disturbances, as well as other symptoms such as dizziness, vertigo, vision problems, nausea, fatigue, and difficulty concentrating. The disruption to the patients’ lives and daily routines is significant. Due to the complexity of the system, diagnosing and treating the causes of the disorder is a challenge.