postural control Flashcards
6 multiple systems required for postural stability and orientation
biomechanical constraints
cognitive processing
movement strategies
control of dynamics
sensory strategies
orientation in space
biomechanics constraints
degrees of freedom
strength
limits of stability
cognitive processing
attention and learning
movement strategies
reactice
anticipatory
voluntary
control of dynamics
gait
proactive
orientation in space
perception
gravity, surfaces, vision
verticality
sensory strategies
sensory integration and sensory reweighting
postural control in stroke
83% of pts 2-4 weeks post stroke = balance disability
motor control impairments in stroke
slow movements, weakness, fatigue, incoordination, decreased force production, co-contraction
what cases motor control impairments in stroke
reduction in # and firing rate of motor units
decreased # of FT MU and increased atrophy of type. 2 fibers =
slower muscle contractile properties = decreased speed
decreased supra spinal drive and increased recurrent inhibition =
slower MU firing rates = decreased strength
increased cocontraction and decreased coordination =
reduced net force = decreased precision
3 global impairments in balance
sensation ( to detect or anticipate postural disturbance)
neural processing ( to select appropriate feedback/feedforward postural control)
effective motor output
Schematic representation of muscle activation (EMG), center of pressure (COP), and center of mass (COM) displacements during external perturbation (horizontal translation of force platform)
Impairment to the timing, magnitude and sequencing of muscle activation
postural control in PD
with ds progression = loss in postural stability, gait dysfunction, frequent falls
how does PC present in PD
lack of balance reaction, flexed posture, decreased trunk rotation, difficulty executing simultaneous movements/sequential movements
short shuffling gait, reduced arm swing, rigidity and tremor of extremities and head
in later stages of PD..
up to 68% falls
postural instability ___ responsive to drug therapy in PD
less
the basal ganglia is responsible for
controlling the flexibility of postural tone
scaling up the magnitude of postural movements
selecting postural strategies for environmental context
automatizing postural responses and gait
rigidity in PD in caused by what main domain of PC
biomechanics constraints (degrees of freedom, strength, limits of stability)
bradykinesia in PD is caused by what domain of PC
control of dynamics (gait, proactive)
movement strategies (reactive, anticipatory, voluntary) and sensory strategies (sensory integration and sensory reweighing)
proprioception deficits in PD are caused by what domain of PC
orientation in space (perception, gravity surfaces vision, verticality)
non motor symptoms in PD are caused by what domain of PC
cognitive processing (attention and learning)
postural control in mTBI
postural instability due to dysfunction in sensory integration
deficits in cognition = attention affects postural control
one of the most common symptoms of mTBI
balance disorders
dizziness reports in mTBI
23-81% report
postural control in MS is due to
extensive damage to CNS
MS demyelination =
sensorimotor cortex, basal ganglia, cerebellum, spinal pathways
motor learning preserved in early phase of MS =
capacity dependent on severity
MS Critical deficit: slowed spinal SS conduction =
delayed postural latencies and increased postural sway
postural control in SCI
aberrant synapse formation leads to inappropriate muscle recruitment and poor coordination
changes in excitability of spinal locomotion networks render some synapses hyperexcitable and some hypoexcitable
chronic SCI postural control
progressive deterioration of muscle properties diminished the ability to generate movements
vestibular system roles
perception of body position and self motion
orientation of trunk to vertical
controls COM (postural reactions)
stabilize head in space
balance evaluation outcome tools for stroke
berg balance scale
dynamic gait index
functional reach tst
TUG
balance outcome tools PD
berg
dynamic gait index
functional gait assessment
mini BesTESt
TUG
balance outcome tools for mTBI
high level mobility assessment HIMAT
balance outcome tools MS
berg
dizziness handicap
TUG w cognitive and manual
balance outcome tools SCI
TUG 10.8 seconds
balance outcomee tools vestibular disorders
dynamic gait index
dizziness handicap inventory
functional gait assessment
healthy older adults according to research - green
(dose-response relationships of ”balance training” parameters; training period of 11-12 wks, frequency of 3x/week, 31-45 minutes per session, 36-40 total # of sessions)-
Variety of training modalities (commonly multimodal exercise-based balance training)-
interventions for chronic stroke according to research - green
(balance/wt. shifting and gait training effective)
intervention for Parkinson - green
exercise interventions probably reduce rate of falls-
mod intensity PRE, 2-3x/wk over 8-10 wks-
intervention for MS - yellow
(balance interventions have a medium effect on outcomes; high intensity* & task-specific interventions are associated with better outcomes)-
intervention for vestibular disorders - yellow
(moderate evidence for improved postural stability following vestibular rehab exercises)
intervention for mTBI
(weak evidence for vestibular rehab exercises, subthreshold aerobic exercise)
intervention for incomplete SCI
[weak evidence for BWST (+ stimulation – FES or tDCS), small scale studies on VR-based balance training show promise]
example of biomechanical issues
ankle strength/ROM
example of stability limits
reaching
example of APAs
planned changed of position
example of reactive responses
unplanned response - step
example of sensory orientation
impact of vision/vestibulat system
example of gait
change gait speed or direction or cognitive load
6 systems of balance
biomechanics constraints
stability limits/verticality
anticipatory postural adjustments
postural responses
sensory orientations
stability in gait
