Balance is a complex process involving the reception and integration of sensory input and the planning and execution of movement. It’s the ability to control the center of gravity over the base of support in any given sensory environment. Reflexes are automatic responses by the peripheral or central nervous system to help support postural orientation and maintain balance; they occur rapidly enough to not be under volitional control.
Balance is a result of the interaction of three separate systems in the body:
- The Visual System, which helps us see things in the environment and orient us to the hazards and opportunities presented.
- The Vestibular System (the inner ear), which provides the brain with information about the position and motion of the head in relation to gravity.
- The Proprioceptors/ Somatosensory Receptors which are located in joints, ligaments, muscles, and the skin to provide information about joint angle, muscle length, and muscle tension all of which is gives information about the position of the limb in space.
The brain needs input from all three systems to distinguish motion of the self from motion of the environment. Any mismatch in these inputs can produce nausea, vomiting and dizziness. Some common examples that we all experience are
- The sense of perceived motion when sitting in a car at a stop light and the car next to you creeps forward, causing you to slam on your brakes
- When on a boat, proprioceptors perceive a rocking boat under your feet, but your eyes see a steady horizon.
More long-term complications with balance can make an affected person feel persistently unsteady or dizzy. In fact, as many as four out of ten Americans will at some point experience an episode of dizziness significant enough to send them to a doctor. These issues can be caused by improper function of the systems mentioned above, health conditions, or as a side effect from some medications. In severe forms, a balance disorder can intensely impact day-to-day activities resulting in an inability to function and cause psychological distress.