balance 4565

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BALANCE

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Balance basics

Balance def.+ ability to maintain one’s

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 neurophysiologicconstraints

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Performing A Comprehensive

Balance Exam

Interview Pt.

PMH

Social Hx Fall hx

Meds

Mental Status

Observation

Biomechanical Factors

Sensation

CoordinationVision

Cone of Stability

Motor CoordinationSensory 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

LOSSway

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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 asa reference to ensure appropriate motorresponses

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Central processing

Compares information from the threesystems

Intact processes result in the right motoroutput

Conflict: Sitting in a car and the car next toyou 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

surfaceM 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 whenthere is a direct perturbation to the pelvis.

I.E. Standing on a curb and being pushed. If

this didn’t 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 perturbatedI.D. the deficit so your intervention will beoptimal

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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 complexvoluntary 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 peripheralfields are seen in the elderly

Dec. sensitivity to low spatial frequencies

results in the requirement for greatercontrast 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 maintenanceof 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 moreproblematic 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 bedetermined.

Reach is the mean difference of initial and

final positions over three test trialsImpaired reach has been found predictive of

falls

C i d f

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Computerized assessment of

postural control

Utilizes computerized measurement of

postural sway using a force platform

Effectively captures age associated changesinc. postural sway during static and

controlled leaning conditions.

Relationship to pt. functional performanceis not clearly established

E l f S O i ti

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Eval of Sensory Organization

Roles of various sensory inputs on the

maintenance of postural control.

Computerized versions measure on stableand moving support surfaces

CTSIB

F ti l P f

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Functional Performance

Measures

Evaluate functional performance of selected

tasks with performance criteria established

for scoring purposesRely on factors such as strength, flexibility,

motor control, and endurance to complete

the activities. Therefore they require morethan 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 task<10sec

<20 sec =cutoff functional ability.

>30 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.< 45/56 increased risk for falls

Best single predictor of falls

Scores < or = to 40 present with almost100% risk of fall

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Tinnetti (POMA)

2 sections balance and gait

Highest possible score 28

Scores <19 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

T t t h

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Treatment approaches

Any underlying impairment potentially modifiableshould 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

T t t f B l

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Treatment of Balance

Dysfunction

1. Weakness: Progress from staticdynamic

2. Challenge on different surfaces, use visual

distortion, modify perturbations3. Vestibular emphasize appropriate strategy to

decrease symptoms.

4. Somatosensory change the external

environment add stimulus to inc. awarenessofextremities

balance 4565

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