Week 6: CPD

Question 1

what does CDP stand for?

Answer 1

computerized dynamic posturography

Question 2

what is the use of CDP?

Answer 2

• helps quantify functional limitations
• allows a view of how the vestib, visual, and proprioceptive systems work together
• can help with differential diagnosis, but does not allow diagnosis of specific pathology
• track progress of treatment plans, such as PT exercises

Question 3

COG

Answer 3

center of gravity over base of support

Question 4

BOS

Answer 4

base of support; the area b/t the feet and surface (are they flat foot, on tip toes)

Question 5

LOS

Answer 5

limits of stability; the outermost perimeter of COG positions

Question 6

what are the 3 strategies used to resist falling

Answer 6

1) ankle: rotation of body about the ankle joint, support is firm and COG movements are slower (sway)
2) hip: rapid movement about the hips, effective for rapid COG movements (jerk)
3) step: used to recover balance when out COG deviates beyond our LOS boundary

Question 7

2 times when balance can be lost

Answer 7

1) lack of sensory information due to altered environments (dark, uneven floor)
2) sensory information is conflicting or misinterpreted (because of impaired sensory input or confused signals)

Question 8

what does SOT stand for

Answer 8

sensory organization test

Question 9

list the 6 SOT subtests

Answer 9

1) eyes open with stable platform and visual surround (baseline)
2) eyes closed with stable platform
3) platform is fixed with visual surround sway-referenced
4) platform is sway-referenced and visual surround is fixed (eyes open)
5) platform is sway-referenced and eyes are closed
6) both platform and visual surround are sway-referenced

Question 10

how to administer the SOT subtests

Answer 10

• 3 trials for each condition
• each trial is 20 seconds
• –the purpose of this is reliability and to determine those who might improve performance with practice
• measures: there are scores for each of the 6 conditions and also a composite score

Question 11

what do we want the SOT equilibrium score to be

Answer 11

want near 100% which indicates minimal sway

Question 12

SOM ratio on SOT test

Answer 12

compares condition 2 with the baseline (somatosensory ratio)

• a ratio of 100 indicates that these are fairly equal
• if lower than 90, ability to use somatosensory input may be impaired

Question 13

VIS ratio on SOT test

Answer 13

compare condition 4 to baseline (visual ratio)

*if the ratio is lower than 70-80, ability to use visual input may be impaired

Question 14

VEST ratio on SOT test

Answer 14

compare condition 5 with baseline (vestibular ratio)

• equilibrium scores are often 50% of baseline
• VEST is usually in the 50-70 range

Question 15

PREF ratio of SOT test

Answer 15

campares scores of sway-referenced vision (conditions 3 & 6) with scores of equivalent eyes closed (conditions 2 & 5)
{vision preference ratio}
*normals are closer to 90-100%
*reduced PREF scores are seen in pts who lose balance with conflicting visual cues

Question 16

strategy analysis as an SOT measure

Answer 16

quantification of ankle and hip movement with regard to amplitude of anterior/posterior sway
*normals are closer to 100%

Question 17

COG alignment on SOT testing

Answer 17

how well the COG aligns with the base of support

• should be centered
• pts will think they are erect when they are not, may be significantly to the right, left, forward, or backward
• there are age-matched norms which is important because COG will change with the normally aging population

Question 18

expected pattern of results for all subtests of the SOT for normals

Answer 18

1) baseline score–near 100
2) usually 90 or higher
3) usually above 90
4) lower than condition 3, but higher than 70
5 & 6) relying on vestibular input alone, expectations drop, may be as much as 50% below baseline
—comparable scores are seen on conditions 5 and 6

Question 19

how would vestibular pathology present on SOT

Answer 19

depressed scores on conditions 5 & 6

Question 20

aphysiologic patterns seen on SOT (faking)

Answer 20

better scores seen on more difficult conditions

• –may be anxious or exaggerating sway
• –other signs of nonorganic sway: side to side sway or circular sway, answer yes to every question of questionnaire

Question 21

voluntary COG control test

Answer 21

pt maintains cursor on center target then moves to one of eight perimeter targets

• movement commands are issued randomly and must be maintained for 5 seconds
• targets are at 45 degree angles to center target
• this test can help give info on limits of stability

Question 22

measures obtained from COG control testing (5)

Answer 22

• reaction time: how fast they react to movement
• movement velocity: how fast they reach the target
• end point excursion: percentage of straight line distance between center and target
• maximum excursion: looks for pt attempts toward additional movement
• directional control: measure deviations from straight path

Question 23

impaired voluntary control shows up as:

Answer 23

• movement restriction
• movement slowing
• reaction time delay
• uncoordinated movement: deviation from the straight line path
• CDP may also be used to quantify function, daily life limitations
• —provides vital information on how to interpret the SOT

Question 24

abnormalities of voluntary control can be due to these issues (4)

Answer 24

• age and weakness of musculature
• anxiety or fear
• central brain disorders (parkinson’s, MS)
• aphysiologic

Question 25

what does MCT stand for

Answer 25

motor control test

Question 26

what does MCT testing measure

Answer 26

*automatic reactions to unexpected balance disturbances

Question 27

how is MCT testing done

Answer 27

• 3 disturbances in forward direction: small, medium, large
• there are 3 disturbances in backward direction: small, medium, and large
• –3 trials of each
• –excursion is dependent upon height

Question 28

what is actually happening in MCT testing

Answer 28

• movement in one direction places COG in opposite direction

* motor response is required to recenter COG over base of support

Question 29

measures of MCT testing

Answer 29

primary measure is latency

• latency: time in msec between beginning of translation and active force exerted by feet
• weight symmetry: percentage of body weight placed on each leg
• –100% corresponds to equal weight bearing
• amplitude scaling:
• –scaling of actions in right and left legs
• –base on pt’s height and weight

Question 30

adaptation test what is it and how is it done

Answer 30

measures how well a person can suppress automatic reactions to surface perturbations

• five toes-up rotations
• five toes-down rotations

Question 31

measure of adaptation test

Answer 31

amplitude of sway after each surface disruption

*larger adaptation scores indicate greater disruption to pt’s stability

Question 32

normal responses expected of MCT tests

Answer 32

there are latency norms

• generally, any latency over 200msec is considered questionable
• should bear weight equally on the two legs
• response amplitude should increase in proportion to increase in translations size

Question 33

normal responses expected of adaptation test

Answer 33

the first scores may be the poorest and then increasingly better scores may be observed

• bilateral prolonged latencies: automatic system may be impaired bilaterally
• –most likely not a vestibular disorder
• unilateral prolonged latencies: may also be associated with CNS disorder
• –may be MS or acoustic neuroma or other demyelinating disease

Question 34

interpretation (of MCT and adaptation test)

Answer 34

• strength asymmetry: pt may favor one leg for balance
• excessive strength: may be overreaction to peripheral stimuli
• aphysiologic: responses to small translations are very large and variable
• –these may be associated with exaggerated sway on SOT results