Week 6: CPD Flashcards
what does CDP stand for?
computerized dynamic posturography
what is the use of CDP?
- 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
COG
center of gravity over base of support
BOS
base of support; the area b/t the feet and surface (are they flat foot, on tip toes)
LOS
limits of stability; the outermost perimeter of COG positions
what are the 3 strategies used to resist falling
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
2 times when balance can be lost
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)
what does SOT stand for
sensory organization test
list the 6 SOT subtests
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
how to administer the SOT subtests
- 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
what do we want the SOT equilibrium score to be
want near 100% which indicates minimal sway
SOM ratio on SOT test
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
VIS ratio on SOT test
compare condition 4 to baseline (visual ratio)
*if the ratio is lower than 70-80, ability to use visual input may be impaired
VEST ratio on SOT test
compare condition 5 with baseline (vestibular ratio)
- equilibrium scores are often 50% of baseline
- VEST is usually in the 50-70 range
PREF ratio of SOT test
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
strategy analysis as an SOT measure
quantification of ankle and hip movement with regard to amplitude of anterior/posterior sway
*normals are closer to 100%
COG alignment on SOT testing
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
expected pattern of results for all subtests of the SOT for normals
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
how would vestibular pathology present on SOT
depressed scores on conditions 5 & 6
aphysiologic patterns seen on SOT (faking)
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
voluntary COG control test
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
measures obtained from COG control testing (5)
- 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
impaired voluntary control shows up as:
- 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
abnormalities of voluntary control can be due to these issues (4)
- age and weakness of musculature
- anxiety or fear
- central brain disorders (parkinson’s, MS)
- aphysiologic
what does MCT stand for
motor control test
what does MCT testing measure
*automatic reactions to unexpected balance disturbances
how is MCT testing done
- 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
what is actually happening in MCT testing
- movement in one direction places COG in opposite direction
* motor response is required to recenter COG over base of support
measures of MCT testing
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
adaptation test what is it and how is it done
measures how well a person can suppress automatic reactions to surface perturbations
- five toes-up rotations
- five toes-down rotations
measure of adaptation test
amplitude of sway after each surface disruption
*larger adaptation scores indicate greater disruption to pt’s stability
normal responses expected of MCT tests
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
normal responses expected of adaptation test
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
interpretation (of MCT and adaptation test)
- 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
