1. Dynamic Posturography
Sensory Organization
Motor Control Testing
Posture Evoked Response

2. Computerized Dynamic Posturography
Sensory Organization Test—measurement of sway energy under various visual and support conditions.
Motor Control Test—measurement of sway in response to tilt or translation in the support surface.
Posture Evoked Responses—EMG recordings during the Motor Control Test.

3. Measuring Sway Energy Pt stands on force plates (pressure transducers)
pick up vertical forces
weight distribution
front-back
left-right
Pick up horizontal sheer forces

4. LIMITS OF STABILITY
The furthest distance in any direction a person can lean away from midline (vertical) without altering the original base-of-support (by stepping, reaching, or falling)

6. Muscle Contractile Patterns
Dynamic Equilibrium
Sensory Organization
Motor Coordination
Determination
of Body Position
Choice of
Body Movement
Compare, Select
& Combine Senses
Select & Adjust
Muscle Contractile Patterns
Visual
System
Vestibular
System
Somato-
Sensation
Ankle
Muscles
Thigh
Muscles
Trunk
Muscles
Environmental
Interaction
Generation of
Body Movement

7. Equilibrium Score
Maximum sway compared to calculated limits of stability
1 – (Max sway/LOS)
100 % = No Sway
0% = Sway reaches LOS
Normed for age and height

8. Sensory Organization Test
Normal
Vision
Eyes
Closed
Sway-Referenced
Vision
Fixed
Surface
Sensory Organization Test
SOT 3 1 2
Sway-Referenced
Surface 4 5 6

9. Equilibrium Scores For each of the 6 conditions Composite of all 6
Derived Sensory Analysis

11. Ratio Conds. Functional Relevance Somatosensory (SOM) 2/1 Visual (VIS)
Pt’s ability to use input from the somatosensory system to maintain balance.
Visual (VIS)
4/1
Pt’s ability to use input from the visual system to maintain balance.
Vestibular (VEST)
5/1
Pt’s ability to use input to the vestibular system to maintain balance.
Preference (PREF)
3+6/2+5
The degree to which pt relies on visual info to maintain balance, even when the info is incorrect.

12. Sensory Analysis

13. Strategy Analysis Hip vs. Ankle Dominant
Hip–high frequency, greater effect in horizontal shearing force
Ankle–low frequency, greater effect in vertical forces.

14. COG Alignment Average weight distribution
Displayed for each conditions
Offsets may reflect:
peripheral sensory
neurogenic
musculoskeletal
adaptation

16. Motor Control Test Support Surface Translations Sway amplitude Latency
Forward
Backward
Sway amplitude
Latency
Weight symmetry

17. Motor ControlTest (MCT)
Amplitudes - Threshold/Small - Mid-range/Medium - Saturating/Large
Directions - Forward - Backward
Measures - Latency - Strength - Symmetry

18. MCT: Normal Latencies
Latencies Slightly Shorter For Large vs Medium Displacements
Latencies Symmetrical Between Left & Right Sides

19. MCT: Latencies Prolonged
Possible Deficits: - Extremity/Spinal Orthopedic Injury - Output Pathways
Problem Conditions: - Minor If Isolated - Major If Combined
Possible Treatments: - Rehabilitation? - Lifestyle
Unilaterally

20. MCT: Latencies Prolonged
Possible Deficits: - Neuropathy - Multiple Sclerosis - Spinal Orthopedic - Brainstem/Cortical
Problem Conditions: - Minor If Isolated - Major If Combined
Possible Treatments: - Lifestyle
Bilaterally

21. Adaptation Test (ADT) Slow Toes Up (Down) Rotations - 8 degrees/sec
Sequences of 5 Trials measure response time

22. ADT: Adaptation Test Normal Adaptation
Sway Energy Scores Higher During Initial Trials
Sway Energy Decreases Progressively With Repeated Rotations
Normal Adaptation

23. ADT: Adaptation Test
Possible Deficits - Mal Adaptation - Ankle Weakness
- ROM impairments
Problem Conditions - Irregular Surfaces
Possible Treatments - Rehabilitation
Failure to Adapt

24. Elderly Fallers: Fail Toes-Up Adaptation Whipple & Wolfson, Balance, 1990
Age-Matched Groups of Fallers & Non-Fallers Compared
Toes-Up Adaptation Failure Significantly Higher in Faller Group

25. Posture Evoked Responses
EMG from:
Gastrocnemius Tibialis anterior

26. PERs Short Latency approx 30 ms Mid Latency approx 73 ms
Monosynaptic stretch reflex
Mid Latency approx 73 ms
Polysynaptic segmental reflex
Long Latency approx 104 ms
Postural response – possibly automatic?