The control of posture and balance necessitates a truly multifaceted interaction of sensory, motor, and central nervous system processes. Each component must be actively contributing to the perceptual experience of the brain otherwise a “mismatch” can occur and dizziness and disequilibrium can be a result. The sensory component involves visual, vestibular (inner ear), proprioceptive (input from joint activity), and somatosensory inputs. The motor component involves what is called feedback of information from sensors in skeletal muscles primarily. Lastly, the central nervous system component includes the vestibular nuclei in the brainstem, the spine, and the cerebellum (small brain). An indispensable element of any test of balance and posture is the ability to actively alter that posture and evaluate the individual’s response to such an intervention.
Dynamic posturography assesses the individual’s postural control in the presence of experimentally induced external perturbations. The perturbation utilized is as simple as a foam cushion. During an actual test protocol, as the individual makes small movements the sensitive detectors in the force platform underneath the subject detect them and transmit this subtle information to a computer. This information is then utilized to determine alterations in what is called the center of pressure (CoP) or sway and aides in the calculation of the direction and amount of sway. This in turn helps formulate a precise diagnosis for rehabilitation.