Balance Flashcards
where is the COM located in most ppl?
2/3 of body height, above BOS, slightly anterior to sacrum
define balance
control of COM over the BOS
list the 3 primary sensory systems involved in our neurophysiological processing of balance
- Vision
- Somatosensory
- Vestibular
how much of each sensory system is weighed during postural control on a firm/stable surface?
- Somatosensory = 70%
- Vestibular = 20%
- Visual = 10%
how much of each sensory system is weighed during postural control on a compliant surface?
- Vestibular = 60%
- Visual = 30%
- Somatosensory = 10%
what is somatosensory input? How does it impact postural control?
- 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
what 2 subtypes of vision make up the visual input aspect of postural control?
- Central (foveal) vision
- Peripheral (ambient) vision
what is central (foveal) vision responsible for?
- environment orientation
- contributes to perceptions of verticality and object motion
- ID of hazards and opportunities
- Recieves more conscious recognition than peripheral vision
what is peripheral (ambient) vision responsible for?
- detects motion of self in relation to the environment
- head movements, postural sway
- largely subconsious
how does visual input impact postural control?
feedforward (anticipatory) postural control in changing environments
T/F: we are more visually reliant when we are younger and become less reliant on vision as we get older and older
FALSE
as we get older we become more visually reliant
how does vestibular input impact postural control?
- provides info to CNS about position and motion of the head
- semicircular canals, otoliths
- VOR, VSR, VCR
- Unique in its ability to distinguish self-motion form environment motion
how does the CNS process all of the inputs from balance senses?
- central sensory structures function first to compare available inputs between 2 sides
- then all 3 sensory systems are compared
- the info is combined to form perceptions of position and motion
*collectively termed multisensory integration/sensory organization
what is multisensory reweighting?
- When changes in the environment occur, the relative availability, accuracy, and usefullness of info from the 3 sensory systems may also change
- Available, accurate, and useful info is “upweighted” whereas unavailable, inaccurate, or less-useful info is “down-weighted”
give an example of multisensory reweighting
walking at night:
- Vision is down-weighted
- Somatosensory and Vestibular info is upweighted
define anticipatory postural control
- Motor planning based on prior experiences to avoid losses of balance
- Voluntary goal-directed movements in preparation for movement
- utilizes feedforward system and cerebellar control
Define Limits of Stability
Points at which COM approaches the limits of the BOS during postural sway or leaning
normal = 8º in all directions
what type of postural sway is normal during sitting? Standing?
- Sitting → around the hip
- Standing → around the ankle
Define reactive postural responses
reaction to unplanned perturbations to balance resulting in displacement of COG or moving the BOS
Feedback system → dependent on fast sensory and motor responses
List the 3 main reactive postural control strategies
- Ankle strategy
- quiet standing
- distal to proximal recruitment
- counteracts small perturbations
- Hip strategy
- proximal to distal recruitment
- counteract large perturbations
- primary strategy for mediolateral control
- Stepping strategy
- used when other 2 fail
- ultimately increases BOS
List some biomechanical considerations to balance
- Ankle PF and DF strength are independent predictors of functional performance
- Plantarflexion strength of big toe affected balance and function in older adults
- Weakness of hip and knee extensors associated with increased likelihood of employing a multi-step strategy to recover from balance perturbations
- Exercise has protective effect on fall risk in older adults
Compare somatosensory input and stability between sitting and standing balance
- Somatosensory input
- Sitting → thighs, buttocks, and fee t
- Standing → ankle/foot
- Stability
- Sitting → less DOF (3)
- Standing → more DOF (6)
Compare: direction of stability, anticipatory postural control, and reactionary stategies between sitting and standing balance
- Direction of stability
- Sitting → A/P most stable, LOB tends to primarily occur laterally
- Standing → lateral more stable than A/P
- Anticipatory Postural Control
- Sitting → Gastroc, quads, glutes
- Standing → Trunk extensors
- Reactionary Strategies
- Sitting → reaching
- Standing → ankle, hip, step
T/F: Gait is a highly variable activity and is a constant challenge to our balance
TRUE
essentially gait is controlled forward transference of COM and we alternate between DLS and SLS
Define dual task control
multitasking and filtering out distractions while maintaining balance
List some intrinsic fall risk factors
- Age
- Impaired balance
- Prior history of falls
- Fear of falling
- Comorbidities/Disease state
- Neuropathic
- MSK
- Visual
- Cognitive
- Cardiovascular
- Meds side effects
List some extrinsic fall risk factors
- Type of surface
- Slippery surface
- Obstacles, stairs, curbs
- Poor lighting or sudden changes in lighting
- Footwear
- Poorly fitted AD and/or orthotics
- Recreational drugs, alcohol
T/F: aging directly increases our likelihood to fall
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
how does aging impact balance strategies?
Essentially we get less effective and efficient at balance strategies
List some visual changes that come with aging that can impact balance
- Presbyopia
- Glare sensitivity
- Reduced dark adapation
- Difficulty shifting focus between near/far
- Slower visual reaction time
- Difficulty distinguishing color
- Loss of peripheral vision
List some common visual pathologies observed with aging
- Cataracts
- Glaucoma
- Macular degeneration
- Diabetic retinopathy
List some functional implications to visual changes with aging (related to balance)
- Higher fall risk at night or in reduced lighting
- At risk to trip over objects due to peripheral loss
- Slower reaction time → reduced reactionary strategies for balance
T/F: there are some significant changes to somatosensory input to balance with aging, more so than vestibular and visual input
FALSE
no real somatosensory changes associated with aging
List some Vestibular changes with aging that impact balance
- loss of hair cells in SCC and otoliths
- calcification of otolithic membranes
- microvascular ischemia
- reduction of vestibular and cerebellar neurons and nuclei
- reduced effectiveness of VOR
List some functional implications to vestibular changes with aging (pertaining to balance)
- less capacity for detection of rotation and gravity-related positions
- reduced gaze stabilization with head movements
- increased postural sway
- sensory substitutions can mask deficit more effectively than with other impaired systems
list some Neuromuscular and MSK changes associated with aging that impact balance
- decrease in # of type I and II fibers (II > I)
- decrease in # of MUs as well as max voluntary muscle activation
- muscle performance (strength, power, endurance) decreases 3% every year after age 60
- decrease in peak anaerobic muscle power
- increase in agonist/antagonist co-activation during volitional movement
- increased muscle CT → decreased flexibility
- increased risk for osteoporosis
List functional implications to changes in neuromuscular and MSK with aging
- reductions in strength, power and muscle endurance have all been tied to balance deficits
- high prevalence of OP results in more risk of fracture when falls occur
- Postrual changes lead to changes in COM/COG/BOS
- greater axial stiffness and reduced flexibility
List some cognitive changes that occur with aging and impact balance
- conceptual reasoning, memory, and processing speed decrease w/time
- decreased use of strategies to improve learning and memory
- reduced selective and divided attention
- gradual reduction in visual constructional skills
- research has shown that concept formation, abstraction, and mental flexibility decline with age, especially after age 70
How do we determine if our pt is “off balance”?
- Observation
- postural alignment, weight distribution
- functional task analysis
- Clinical history taking
- Subjective Outcome measures
- Objective Outcome measures
- cut-off scores
- minimum detectable change (MCD)
- meaningful clinically important difference (MCID)
List some subjective outcome measures for balance
- ABC (activities-specific balance confidence scale)
- Tinetti Falls Efficacy Scale
What is the ABC?
- 16-item (0-100 score)
- measures balance confidence in performing various activities w/o losing balance or experiencing a sense of unsteadiness
- evaluates vestibular, non-vestibular balance tasks and functional mobility
What is Tinetti Falls Efficacy Scale?
- 10-item
- each item is rated from 1 (very confident) to 10 (not confident at all)
- Assesses perception of balance and stability during ADLs as well as non-vestibular balance tasks, functional mobility, life participation, and self-efficacy
- Cut off scores:
- >80 increased risk of falling
- >70 indicates fear of falling
List some outcome measures that look at the Limits of Stability
- Functional reach test
- Multidirectional reach test
List some outcome measures that look at anticipatory postural control
- 5 TSTS
- BBS
- Mini BESTest
- 4 square step test
list some outcome measures that look at reactive postural responses
- Push/pull test
- Mini BESTest
- DGI/FGA
- Tinetti
List some exams/tests that look at sensorimotor integration
- Romberg Test
- Sensory Organization Test (SOT)
- Clinical Test for Sensory Interaction in Balance (CTSIB)
- “Foam and Dome Test”
What are the APTA EDGE 6 Core Outcome Measures?
- Berg Balance Scale
- Functional Gait Assessment
- Activities-Specific Balance Confidence Scale
- 10m walk test
- 6 minute walk test
- 5 times sit to stand
the principles of neuroplasticity are crucial when training what aspect of balance?
Anticipatory Postural Control
Especially: repetition, specificity matters, and transference
