BALANCE

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BALANCE

• V.Southard PT MS GCS

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Balance basics

• Balance def. ability to maintain ones COM
  within the BOS in a given sensory environment.
• Systems involved MS, NM Somatosensory,visual,and
  vestibular

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Stabilizing postural responses

• Postural control is maintained in a cooperative
  manner

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Faulty balance

• Pathology in any system
• Disruption between the potential biomechanical
  and neurophysiologic constraints

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Performing A Comprehensive Balance Exam

• Interview Pt.
• PMH
• Social Hx
• Fall hx
• Meds
• Mental Status
• Observation

• Biomechanical Factors
• Sensation
• Coordination
• Vision
• Cone of Stability
• Motor Coordination
• Sensory Organization

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Components of Postural Control

• Limits of Stability maximum angle from vertical
  that is tolerated without the loss of balance.
• Base of support proportional with LOS
• Height of COM is inversely proportional to LOS
• Sway

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Sensory organization

• Afferents provide information about body position
  from 3 sources
• Somatosensory
• Visual
• Vestibular

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Somatosensory

• Peripheral receptors and Joint receptors of the
  foot and ankle
• Detects motion of the body with respect to the
  supporting surface
• Detects motion of the body segments with respect
  to each other
• In impairment delayed responses of 20-30 msec
• Role in scaling motor response to perturb.

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Vision

• Provides info about body position relative to
  environment and moving environment itself
• Most sensitive to low frequency stimulation
• When moving more information is processed

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Vestibular

• Two Functions
• Stabilizes the eyes during head movement to
  assure steady gaze
• Maintains upright vertical body alignment during
  head movement
• Slowest of the three afferent systems
• With conflicting info, vestibular system acts as
  a reference to ensure appropriate motor responses

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Central processing

• Compares information from the three systems
• Intact processes result in the right motor output
• Conflict Sitting in a car and the car next to
  you moves
• visual identifies movement of environment
• somatosensory perceives no change in position

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Motor Coordination

• Motor synergies maintain upright posture
• Response depends on
• Latency of response
• Task dependence
• Invariance of motor output
• 
  

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Automatic postural reactions

• Def Synergistic patterns of activation of LE
  muscle in response to perturbation
• Occur to maintain the COM within the BOS
• Three synergistic motor responses are
• Ankle strategy
• Hip strategy
• Stepping strategy

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Ankle Strategy

• Used during quiet stance or secondary to small
  perturbations on a normal support surface
• M activity initiates distally at the ankle and
  the radiates to the thigh and abdominal m,
  producing torque at the ankle

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Hip Strategy

• Occurs in response to moderate perturbation and
  or when the support surface is narrow relative to
  the base of support, or when there is a direct
  perturbation to the pelvis. I.E. Standing on a
  curb and being pushed. If this didnt occur, you
  would have to step off the curb
• Muscle are activated in prox to distal

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Stepping Strategy

• Occurs when the LE and trunk cannot maintain the
  COM with the BOS.
• A step will Increase the BOS or realign it

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Evaluating Automatic Postural Reactions

• Selection of the appropriate synergy
• Latency of response
• Amplitude of response or evidence of
  cocontraction
• Visually assess the pts. motor response when
  perturbated
• I.D. the deficit so your intervention will be
  optimal

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Balance strategies

• Selected in response also to sensory input
• expectation
• prior experience
• practice

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Adaptation and Flexibility

• Assess motor synergies and determine whether they
  are appropriate
• Change the testing conditions by
• Changing the support surface
• Varying the magnitude of the perturbation
• Pts. should be able to utilize a variety of
  strategies

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Cognition

• Attention is not required to maintain balance
• However we monitor the environment
• Inattention to the environment may result in
  being at risk for falls

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Increased risk for falls MS impairment

• Biomechanical limitations
• ROM
• M weakness

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Neuromuscular impairment

• Loss of m mass, dec. force production, and
  decreased isokinetic jt. Mvt., impaired motor
  learning, slower simple and complex voluntary
  reaction times

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Function of afferent system

• Redundancy allows pts. with impairments to
  maintain upright postural alignment

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Somatosensory impairments

• Elderly have 30-50 dec. vibration sense at the
  ankle
• Jt. Position sense is dec.
• Peripheral Nerve conduction slows with age

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Visual impairments

• Dec. visual acuity, reduced visual fields,
  increased susceptibility to glare, poor depth
  perception, and reduction in peripheral fields
  are seen in the elderly
• Dec. sensitivity to low spatial frequencies
  results in the requirement for greater contrast
  to detect spatial differences successfully

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Vestibular impairments

• Loss of the vestibular system results in
  appropriate use of the ankle strategy, but he hip
  strategy is not used in the maintenance of
  upright control
• Declines in auditory and vestibular function are
  widely documented in the elderly

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Sensory organization testing

• Also referred to as CTSIB.
• 6 conditions the pt is viewed for degree of sway
  and maintenance of position.
• Enables the examiner to select and weigh
  conflicting sensory references
• Misleading visual information is more problematic
  than absent vision

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Balance Assessment Tools

• Should have the following characteristics
• Reliable
• Valid
• Sensitive
• Specific
• Ability to detect change over time

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Assessment Tools

• Measures of Standing Balance
• Romberg Assess the integrity of the neural
  systems for individuals with neurosyphyllis.
  Selective loss of the posterior columns.
• Pt stands, both feet together with narrow BOS
  arms folded across chest.
• Assess the amt. Of postural sway observed with
  eyes open and then closed for 30 sec.
• How long the pt. can maintain the position is
  timed.

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One leg stance time

• Document length of time pt. maintains position
• Important predictor of falls in the elderly

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Functional Reach

• DEF Max distance a person can reach forward
  while maintaining a fixed base of support.
  Margin of stability can be determined.
• Reach is the mean difference of initial and final
  positions over three test trials
• Impaired reach has been found predictive of falls

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Computerized assessment of postural control

• Utilizes computerized measurement of postural
  sway using a force platform
• Effectively captures age associated changes inc.
  postural sway during static and controlled
  leaning conditions.
• Relationship to pt. functional performance is not
  clearly established

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Eval of Sensory Organization

• Roles of various sensory inputs on the
  maintenance of postural control.
• Computerized versions measure on stable and
  moving support surfaces
• CTSIB

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Functional Performance Measures

• Evaluate functional performance of selected tasks
  with performance criteria established for scoring
  purposes
• Rely on factors such as strength, flexibility,
  motor control, and endurance to complete the
  activities. Therefore they require more than
  balance
• Ex TUG, Berg, Tinetti

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Timed Up and Go

• Measures the time required to rise from a std.
  Chair, walk 3 meters, turn around, return, and
  sit down.
• I ADLs scored tasklt10sec
• lt20 sec cutoff functional ability.
• gt30 sec. Had impaired mobility and inc risk for
  falls

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BERG functional balance scale

• 14 tasks ranging in difficulty. Each item is
  scored 0-4 based on specific criteria. Scale
  allows grading to reflect improvement.
• lt 45/56 increased risk for falls
• Best single predictor of falls
• Scores lt or to 40 present with almost 100 risk
  of fall

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Tinnetti (POMA)

• 2 sections balance and gait
• Highest possible score 28
• Scores lt19 indicate high risk for falls
• 19-24 at risk, but not high risk
• Attempts to quantify quality of gait performance,
  captures higher level of function. Pt may use an
  assistive device

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Treatment approaches

• Any underlying impairment potentially modifiable
  should be addressed
• If not modifiable, compensation techniques and
  pt. education should be the initial focus.
• Practice reactions to improve reaction time
• Comprehensive tx plans include inc. pts. ability
  to maintain postures, control movements of the
  COM, respond to disturbances of the COM

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Treatment of Balance Dysfunction

• 1. Weakness Progress from static?dynamic
• 2. Challenge on different surfaces, use visual
  distortion, modify perturbations
• 3. Vestibular emphasize appropriate strategy to
  decrease symptoms.
• 4. Somatosensory ? change the external
  environment add stimulus to inc. awareness
  ofextremities