Balance

Question 1

where is the COM located in most ppl?

Answer 1

2/3 of body height, above BOS, slightly anterior to sacrum

Question 2

define balance

Answer 2

control of COM over the BOS

Question 3

list the 3 primary sensory systems involved in our neurophysiological processing of balance

Answer 3

1. Vision
2. Somatosensory
3. Vestibular

Question 4

how much of each sensory system is weighed during postural control on a firm/stable surface?

Answer 4

1. Somatosensory = 70%
2. Vestibular = 20%
3. Visual = 10%

Question 5

how much of each sensory system is weighed during postural control on a compliant surface?

Answer 5

1. Vestibular = 60%
2. Visual = 30%
3. Somatosensory = 10%

Question 6

what is somatosensory input? How does it impact postural control?

Answer 6

• receptors located in joints, ligaments, muscles, skin provide info about muscle length, stretch, tension and contraction as well as pressure and joint position
• this is the dominant sense for upright postural control
  
  • most active in triggering automatic postural responses

Question 7

what 2 subtypes of vision make up the visual input aspect of postural control?

Answer 7

1. Central (foveal) vision
2. Peripheral (ambient) vision

Question 8

what is central (foveal) vision responsible for?

Answer 8

1. environment orientation
2. contributes to perceptions of verticality and object motion
3. ID of hazards and opportunities
4. Recieves more conscious recognition than peripheral vision

Question 9

what is peripheral (ambient) vision responsible for?

Answer 9

1. detects motion of self in relation to the environment
   
   • head movements, postural sway
2. largely subconsious

Question 10

how does visual input impact postural control?

Answer 10

feedforward (anticipatory) postural control in changing environments

Question 11

T/F: we are more visually reliant when we are younger and become less reliant on vision as we get older and older

Answer 11

FALSE

as we get older we become more visually reliant

Question 12

how does vestibular input impact postural control?

Answer 12

1. provides info to CNS about position and motion of the head
   
   • semicircular canals, otoliths
   • VOR, VSR, VCR
2. Unique in its ability to distinguish self-motion form environment motion

Question 13

how does the CNS process all of the inputs from balance senses?

Answer 13

1. central sensory structures function first to compare available inputs between 2 sides
2. then all 3 sensory systems are compared
3. the info is combined to form perceptions of position and motion

*collectively termed multisensory integration/sensory organization

Question 14

what is multisensory reweighting?

Answer 14

1. When changes in the environment occur, the relative availability, accuracy, and usefullness of info from the 3 sensory systems may also change
2. Available, accurate, and useful info is “upweighted” whereas unavailable, inaccurate, or less-useful info is “down-weighted”

Question 15

give an example of multisensory reweighting

Answer 15

walking at night:

1. Vision is down-weighted
2. Somatosensory and Vestibular info is upweighted

Question 16

define anticipatory postural control

Answer 16

1. Motor planning based on prior experiences to avoid losses of balance
2. Voluntary goal-directed movements in preparation for movement
3. utilizes feedforward system and cerebellar control

Question 17

Define Limits of Stability

Answer 17

Points at which COM approaches the limits of the BOS during postural sway or leaning

normal = 8º in all directions

Question 18

what type of postural sway is normal during sitting? Standing?

Answer 18

1. Sitting → around the hip
2. Standing → around the ankle

Question 19

Define reactive postural responses

Answer 19

reaction to unplanned perturbations to balance resulting in displacement of COG or moving the BOS

Feedback system → dependent on fast sensory and motor responses

Question 20

List the 3 main reactive postural control strategies

Answer 20

1. Ankle strategy
   
   • quiet standing
   • distal to proximal recruitment
   • counteracts small perturbations
2. Hip strategy
   
   • proximal to distal recruitment
   • counteract large perturbations
   • primary strategy for mediolateral control
3. Stepping strategy
   
   • used when other 2 fail
   • ultimately increases BOS

Question 21

List some biomechanical considerations to balance

Answer 21

1. Ankle PF and DF strength are independent predictors of functional performance
2. Plantarflexion strength of big toe affected balance and function in older adults
3. Weakness of hip and knee extensors associated with increased likelihood of employing a multi-step strategy to recover from balance perturbations
4. Exercise has protective effect on fall risk in older adults

Question 22

Compare somatosensory input and stability between sitting and standing balance

Answer 22

1. Somatosensory input
   
   • Sitting → thighs, buttocks, and fee t
   • Standing → ankle/foot
2. Stability
   
   • Sitting → less DOF (3)
   • Standing → more DOF (6)

Question 23

Compare: direction of stability, anticipatory postural control, and reactionary stategies between sitting and standing balance

Answer 23

1. Direction of stability
   
   • Sitting → A/P most stable, LOB tends to primarily occur laterally
   • Standing → lateral more stable than A/P
2. Anticipatory Postural Control
   
   • Sitting → Gastroc, quads, glutes
   • Standing → Trunk extensors
3. Reactionary Strategies
   
   • Sitting → reaching
   • Standing → ankle, hip, step

Question 24

T/F: Gait is a highly variable activity and is a constant challenge to our balance

Answer 24

TRUE

essentially gait is controlled forward transference of COM and we alternate between DLS and SLS

Question 25

Define dual task control

Answer 25

multitasking and filtering out distractions while maintaining balance

Question 26

List some intrinsic fall risk factors

Answer 26

1. Age 2. Impaired balance 3. Prior history of falls 4. Fear of falling 5. Comorbidities/Disease state * Neuropathic * MSK * Visual * Cognitive * Cardiovascular 6. Meds side effects

Question 27

List some extrinsic fall risk factors

Answer 27

1. Type of surface 2. Slippery surface 3. Obstacles, stairs, curbs 4. Poor lighting or sudden changes in lighting 5. Footwear 6. Poorly fitted AD and/or orthotics 7. Recreational drugs, alcohol

Question 28

T/F: aging directly increases our likelihood to fall

Answer 28

FALSE aging negatively impacts crucial systems involved in our balance, which leads to higher risk for falls. It does not directly cause increased fall risks

Question 29

how does aging impact balance strategies?

Answer 29

Essentially we get less effective and efficient at balance strategies

Question 30

List some visual changes that come with aging that can impact balance

Answer 30

1. Presbyopia 2. Glare sensitivity 3. Reduced dark adapation 4. Difficulty shifting focus between near/far 5. Slower visual reaction time 6. Difficulty distinguishing color 7. Loss of peripheral vision

Question 31

List some common visual pathologies observed with aging

Answer 31

1. Cataracts 2. Glaucoma 3. Macular degeneration 4. Diabetic retinopathy

Question 32

List some functional implications to visual changes with aging (related to balance)

Answer 32

1. Higher fall risk at night or in reduced lighting 2. At risk to trip over objects due to peripheral loss 3. Slower reaction time → reduced reactionary strategies for balance

Question 33

T/F: there are some significant changes to somatosensory input to balance with aging, more so than vestibular and visual input

Answer 33

FALSE no real somatosensory changes associated with aging

Question 34

List some Vestibular changes with aging that impact balance

Answer 34

1. loss of hair cells in SCC and otoliths 2. calcification of otolithic membranes 3. microvascular ischemia 4. reduction of vestibular and cerebellar neurons and nuclei 5. reduced effectiveness of VOR

Question 35

List some functional implications to vestibular changes with aging (pertaining to balance)

Answer 35

1. less capacity for detection of rotation and gravity-related positions 2. reduced gaze stabilization with head movements 3. increased postural sway 4. sensory substitutions can mask deficit more effectively than with other impaired systems

Question 36

list some Neuromuscular and MSK changes associated with aging that impact balance

Answer 36

1. decrease in # of type I and II fibers (II \> I) 2. decrease in # of MUs as well as max voluntary muscle activation 3. muscle performance (strength, power, endurance) decreases 3% every year after age 60 4. decrease in peak anaerobic muscle power 5. increase in agonist/antagonist co-activation during volitional movement 6. increased muscle CT → decreased flexibility 7. increased risk for osteoporosis

Question 37

List functional implications to changes in neuromuscular and MSK with aging

Answer 37

1. reductions in strength, power and muscle endurance have all been tied to balance deficits 2. high prevalence of OP results in more risk of fracture when falls occur 3. Postrual changes lead to changes in COM/COG/BOS 4. greater axial stiffness and reduced flexibility

Question 38

List some cognitive changes that occur with aging and impact balance

Answer 38

1. conceptual reasoning, memory, and processing speed decrease w/time 2. decreased use of strategies to improve learning and memory 3. reduced selective and divided attention 4. gradual reduction in visual constructional skills 5. research has shown that concept formation, abstraction, and mental flexibility decline with age, especially after age 70

Question 39

How do we determine if our pt is "off balance"?

Answer 39

1. Observation * postural alignment, weight distribution * functional task analysis 2. Clinical history taking 3. Subjective Outcome measures 4. Objective Outcome measures * cut-off scores * minimum detectable change (MCD) * meaningful clinically important difference (MCID)

Question 40

List some subjective outcome measures for balance

Answer 40

1. ABC (activities-specific balance confidence scale) 2. Tinetti Falls Efficacy Scale

Question 41

What is the ABC?

Answer 41

1. 16-item (0-100 score) 2. measures balance confidence in performing various activities w/o losing balance or experiencing a sense of unsteadiness 3. evaluates vestibular, non-vestibular balance tasks and functional mobility

Question 42

What is Tinetti Falls Efficacy Scale?

Answer 42

1. 10-item * each item is rated from 1 (very confident) to 10 (not confident at all) 2. Assesses perception of balance and stability during ADLs as well as non-vestibular balance tasks, functional mobility, life participation, and self-efficacy 3. Cut off scores: * \>80 increased risk of falling * \>70 indicates fear of falling

Question 43

List some outcome measures that look at the Limits of Stability

Answer 43

1. Functional reach test 2. Multidirectional reach test

Question 44

List some outcome measures that look at anticipatory postural control

Answer 44

1. 5 TSTS 2. BBS 3. Mini BESTest 4. 4 square step test

Question 45

list some outcome measures that look at reactive postural responses

Answer 45

1. Push/pull test 2. Mini BESTest 3. DGI/FGA 4. Tinetti

Question 46

List some exams/tests that look at sensorimotor integration

Answer 46

1. Romberg Test 2. Sensory Organization Test (SOT) 3. Clinical Test for Sensory Interaction in Balance (CTSIB) * "Foam and Dome Test"

Question 47

What are the APTA EDGE 6 Core Outcome Measures?

Answer 47

1. Berg Balance Scale 2. Functional Gait Assessment 3. Activities-Specific Balance Confidence Scale 4. 10m walk test 5. 6 minute walk test 6. 5 times sit to stand

Question 48

the principles of neuroplasticity are crucial when training what aspect of balance?

Answer 48

Anticipatory Postural Control Especially: repetition, specificity matters, and transference