Introduction
Quantifying balance — the science behind the platform.
Posturography turns the multisensory work of standing into numbers. Computerized dynamic posturography isolates and challenges vision, vestibular and somatosensory inputs in turn, producing a sensory profile no clinical test can match — useful for differential diagnosis, rehabilitation planning, fall-risk and return-to-play.
Standing upright is a fast, automatic negotiation between three sensory systems: vision, the vestibular apparatus in the inner ear, and the proprioceptive feedback from muscles and joints. Posturography measures how well that negotiation works, and how the patient responds when one of the systems is challenged.
The simplest form, static posturography, just records body sway during quiet stance on a force plate. The most sophisticated, Computerized Dynamic Posturography (CDP), adds a moving platform and a moving visual surround to expose how the central nervous system reweights the senses under conflict.
The vestibular system encodes head acceleration through the semicircular canals and otoliths, providing the inertial reference frame for gaze stability and postural control.1 The proprioceptive and visual systems contribute parallel estimates of body position and motion; the central nervous system fuses them into a single percept.2 Posturography's power is that it can subtract any one of these channels and watch what happens.
The CDP battery has four parts: the Sensory Organization Test(SOT) for sensory weighting, the Motor Control Test (MCT) for automatic postural reflexes, the Adaptation Test(ADT) for motor learning, and the Limits of Stability (LoS) for voluntary control. Each produces objective, quantitative metrics keyed to age-matched norms.6
The clinical position of CDP is functional, not anatomic. It will tell you that a patient's balance depends abnormally on vision, or that the vestibular channel is under-weighted — but it will not localise the lesion. The complementary tests are caloric, vHIT, VEMP and imaging; CDP earns its keep by translating those site-of-lesion findings into a functional picture of how the patient actually stands.5
The cerebellum's role in tuning postural responses, exposed by the ADT, makes CDP one of the few clinical tools that quantifies motor learning at the bedside.3,4 Combined with the SOT's sensory profile, the result is a multi-axis description of the patient's balance system that informs rehabilitation, surgery, and disposition decisions across vestibular, neurological, geriatric and concussion populations.
The centre of pressure — the raw signal
Every posturographic measurement begins here: the centre of pressure under the feet moves in real time as the patient sways. Static posturography records that trajectory during quiet stance; everything more sophisticated adds perturbations to it.
Sway area small, CoP excursion within a narrow envelope.
Where to start
Abbreviations used in this chapter
Hover any abbreviation in the prose for an instant tooltip with the full expansion and a one-line clinical gloss. The full set is listed below.
- CDP
- Computerised Dynamic Posturography — Quantitative balance assessment on a moving platform with sway-referenced visual surround.
- SOT
- Sensory Organization Test — Six-condition CDP protocol that probes how the patient weights vestibular, visual and somatosensory inputs.
- MCT
- Motor Control Test — CDP test of automatic postural reflexes following sudden platform translations.
- ADT
- Adaptation Test — CDP test of motor learning across repeated unexpected platform tilts.
- LoS
- Limits of Stability — Voluntary-lean test in eight directions — measures reaction time, excursion and directional control.
- CoP
- Centre of Pressure — Point of ground-reaction-force application; the raw sway signal captured by force plates.
- VOR
- Vestibulo-Ocular Reflex — Reflex that drives the eyes equal-and-opposite to head movement to stabilise gaze.
- VEMP
- Vestibular-Evoked Myogenic Potential — Otolith reflex test — cVEMP (saccule) and oVEMP (utricle).
- vHIT
- video Head Impulse Test — Goggle-mounted camera quantifies VOR gain for each canal; detects covert saccades the bedside HIT misses.
- VNG
- Videonystagmography — Goggle-recorded vestibular battery — gaze, pursuit, saccade, OKN, positional, calorics.
- PPPD
- Persistent Postural-Perceptual Dizziness — Chronic functional vestibular disorder by Bárány criteria; ≥3 months of dizziness worse standing or with visual motion.
- MS
- Multiple Sclerosis — Demyelinating disease with characteristic central oculomotor signs (INO, GEN, downbeat nystagmus).
- TBI
- Traumatic Brain Injury
- AI
- Artificial Intelligence
- ML
- Machine Learning
- VR
- Virtual Reality
- AR
- Augmented Reality
- IMU
- Inertial Measurement Unit — Gyroscope-based sensor used in head-tracking and rehab biofeedback devices.
- FGA
- Functional Gait Assessment
- FCD
- Functional Conversion Disorder
- CNS
- Central Nervous System