Computerized Dynamic Posturography (CDP) provides a differential assessment of impairments through the following three sensory and motor protocols:
The Sensory Organization Test (SOT) objectively identifies problems with postural control by assessing the patient’s ability to make effective use of (or suppress inappropriate) visual, vestibular, and proprioceptive information.
During the SOT, useful information delivered to the patient’s eyes, feet and joints is effectively eliminated through calibrated “sway referencing” of the support surface and/or visual surround. The support surface and/or visual surround tilt to directly follow the patient’s anteroposterior body sway, eliminating orientation information. By controlling the usefulness of the sensory (visual and proprioceptive) information through sway referencing and/or eyes open/closed conditions, the SOT protocol systematically eliminates useful visual and/or support surface information and creates sensory conflict situations. These conditions isolate vestibular balance control, as well as stress the adaptive responses of the central nervous system. In short, patients may display either an inability to make effective use of individual sensory systems, or inappropriate adaptive responses, resulting in the use of inaccurate sense(s).
The SOT protocol is comprised of the following six sensory conditions:
- Eyes open, fixed surface and visual surround.
- Eyes closed, fixed surface.
- Eyes open, fixed surface, sway referenced visual surround.
- Eyes open, sway referenced surface, fixed visual surround.
- Eyes closed, sway referenced surface.
- Eyes open, sway referenced surface and visual surround.
The Motor Control Test (MCT) assesses the patient’s ability to quickly and automatically recover from unexpected external provocations. Sequences of small, medium or large (scaled to the patient’s height) platform translations in forward and backward directions elicit automatic postural responses. Measurements include onset timing, strength and lateral symmetry of responses.
The Adaptation Test (ADT) assesses the patient’s ability to modify motor reactions and minimize sway when the support moves unpredictably in the toes-up or toes-down direction. For each platform rotation, a sway energy score quantifies the magnitude of the force response required to overcome induced postural instability. This adaptive test simulates daily life conditions such as irregular support surfaces.