Activity in Cerebral Palsy: How it helps muscles

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Activity in Cerebral PalsyHow it helps muscles
( brains!)
Diane L. Damiano, PhD PT National Institutes of
Health Bethesda MD USA
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TAKE HOME MESSAGE

• Activity,
• Activity,
• Activity.

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Activity and Cerebral Palsy

• Those with CP have one of the most sedentary
  lifestyles among pediatric disabilities (Longmuir
  Bar-Or 2000)
• Van den Berg-Emons et al (1995) estimated that
  average child with CP would need to exercise
  2.5 hours/day to reach activity levels of peers

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Step Counts in CP by GMFCS LEVEL vs. Peers
(Bjornson et al 2007)
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Outline

• Discuss generalized effects of activity on muscle
  structure function and motor outcomes
  (optimizing physical rehabilitation)
• Neurobiology of activity potential role of
  activity-based protocols for promoting neural
  recovery and restoration of function

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• Muscles now known to be one of the most
  plastic tissues in the body
• Muscles respond in a fairly stereotypical
  manner to the amount and type of activity imposed
  upon them
• Lieber et al, 2004

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Muscle Myths

• Previously thought that fiber types and of
  fibers determined genetically and could not
  change (marathon runners sprinters born, not
  made)
• Rehabilitation of those with CP and other CNS
  disorders failed to include muscle strengthening
  or other intense training paradigms because it
  would gt spasticity.

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How Do Muscles Adapt? (Harridge, Exp Physiol,
Review 2007)

• Two basic mechanisms at the level of the muscle
  fiber (cell)
• Change in mm size
• Primarily by increase/decrease in fiber diameter
• Mediated by satellite cells that repair or grow
  muscles (or replace themselves)
• Change in size directly related to maximal force
  output
• (In extreme cases (elite bodybuilders) perhaps
  normal development (Sjostrom, 1992) the number of
  fibers may increase)
• Change in protein isoform (MHC) composition
• affects maximal shortening velocity (faster if gt
  Type II)

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How can muscle adaptations be indiced?

• Decrease mm size
• Immobilization
• Decrease activity level (contractile activity)
• Weightlessness
• Increase mm size
• Placing loads on muscles, e.g. progressive
  resistance exercise (PRE)
• Change protein isoform (MHC) composition
• High or low frequency electrical stimulation or
  high intensity (speed) voluntary training
• Denervation

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Muscle plasticity in adult developing skeletal
mm changes in MHC composition induced by
inactivity fast-type activity in Type I fibers
Schiaffino et al. Physiology 22 269-278 2007

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What happens to muscles in CP?

• From infancy on ( perhaps before) children w/ CP
  do not move as much as those w/o CP move
  differently
• Muscles cells are not mature at birth therefore
  in CP, muscles may fail to develop properly
  from outset
• If muscles are not used, they become
  progressively weaker then it becomes even harder
  to move
• To what extent is this preventable or reversible?

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What CP Care Environment Does to Muscles

• Many treatments in CP weaken muscles
• Muscle-tendon lengthenings ltforce-generation
  capability (Delp Zajac, 1992)
• Orthoses can cause atrophy of calf mms
• Botulinum toxin paralyzes one mm at a joint to
  allow gt stretch enhance opposite mm function
• ITB depresses involuntary voluntary muscle
  activity
• PT casting, splinting, restrictive garments,
  prior emphasis on movement quality vs. quantity,
  ban on strengthening can limit muscle development

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Strength in CP vs. Non-CP Dominant Side
(Wiley Damiano, DMCN 1998)
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Non-Dominant Side
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Strength by GMFCS Level
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Muscle Strengthening

• Multiple reviews in CP other conditions showing
  that strength is predictably increased (Dodd,
  Tayl0r Damiano 2002 Taylor, Dodd Damiano
  2006)
• Changes in gait speed other aspects of
  functioning noted often but not consistently
• Depends on dose and duration. Must be done
  properly for sufficient time to achieve
  benefits
• Must be maintained across lifespan

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Muscle Fatigue in CP

• Fatigue is cited as main cause for decline or
  cessation in walking in CP (Bottos 2004)
• Cardio-respiratory endurance lower in CP
• No reports on voluntary muscle fatigue in CP
• We hypothesized that those with CP would be more
  fatigable than age-matched peers, and that
  endurance would worsen with level of involvement

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Methods

• Subjects 18 w/ CP 15 controls (ages 10-23y)
• Fatigue Protocol
• Biodex isokinetic dynamometer
• Consecutive, maximal, (concentric)
• reciprocal knee extension/flexion reps
• 35 repetitions at 60 deg/s
• Instructions Push all the way up as hard and
  fast as possible pull down.
• Verbal encouragement each repetition

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Methods

• Computed slope of the decline in torque
  (normalized to peak torque) in the quadriceps
  hamstrings mms

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Results for the Quadriceps
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Correlation of Slope GMFCS
Spearman (r) -0.50, p .035
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RESULTS

• Group w/ CP had greater endurance in their
  quadriceps than controls hamstrings not
  different in CP
• Stackhouse et al. 2005 evaluated fatigue with
  electrically elicited contractions found
  quadriceps (but not triceps surae) to be less
  fatigable in CP
• We further found that the less functional (and
  weaker) they were, the greater their endurance
  tended to be
• HOW DO YOU EXPLAIN THIS?

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FATIGUE PARADOX

• Stronger individuals may fatigue more rapidly
  (inconsistent)
• Muscles in CP have predominance of Type I fibers
  (Rose 2001)
• The subjective complaint of fatigue is likely due
  to weakness. Individuals with CP are working at
  higher of maximum, so this makes them feel more
  tired during a similar task - same thing happens
  in elderly
• Loss of strength with age increases fatigue even
  more
• Suggests that the most effective long term
  strategy to avoid fatigue is to maintain/increase
  strength to lessen relative effort

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In Vivo Evidence of Muscle Plasticity
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THIGH CT SCANS IN TWO MATCHED PATIENTS WITH
COMPLETE SCI (n56)
TRADTIONAL PT CONTROL 6
MOS. OF FESCYCLING
(Sadowsky, McDonald, Damiano et al)
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Introduction to Muscle Architecture

• Fascicle geometry
• Fascicle Length (FL)
• Fascicle Angle (FA)
• FL MT / sin (FA) (Shortland et al, 2002)
• Muscle size
• (2D) Muscle thickness (MT)
• (3D) Cross-sectional area (CSA)
• (3D) Muscle volume
• (3D) Muscle length

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RECTUS FEMORIS 3D US
Longitudinal ?
RF
Axial ?
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Relationship of muscle size to strength in CP

• Ohata et al (2004, 2006) suggested that muscle
  thickness could be used as a surrogate measure of
  strength in CP, especially for those who are too
  young, too cognitively impaired or lack
  sufficient motor control.

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MUSCLE THICKNESS IN ADULTS WITH CP (Ohata et al,
Phys Ther 2006)
BY STANDING ABILITY
BY GMFCS LEVEL
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Muscle Ultrasound (US)

• GE VOLUSON730 E linear (2D) volume (3D) probes
  
• PARTICIPANTS18 w/CP (12 ambulators), 20
  Controls 11 measured before after intense
  summer sports camp
• METHODS
• Muscles
• Rectus Femoris (RF)
• Vastus lateralis (VL)
• Position Supine with hips knees in extension
• Measurements
• RF 50 of ASIS to Patella
• VL 50 of GT to lateral femoral condyle

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Relationship of Muscle Thickness to Peak Torque
VL MT (mm)
ISOMETRIC PEAK TORQUE (N.m)
p lt 0.05 p lt 0.01
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Rectus Femoris Cross-Sectional Areain CP by
GMFCS Level and vs. Control
GMFCS X Normalized Cross-Sectional Area r
0.50, p .05
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RECTUS FEMORIS THICKNESS
CONTROL (23kg) RFT20.0 mm
GMFCS II (21kg) RFT13.3 mm
GMFCS III (25.6kg) RFT105 mm
GMFCS IV (28.4kg) RFT10.4 mm
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CHANGE IN RECTUS CROSS SECTIONAL AREA (CSA) BY
WEEKS IN SPORTS CAMP
Does intense and prolonged physical activity gt mm
size in CP? (new evidence suggesting this is
possible in as few as 3 weeks)
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NEUROBIOLOGY OF ACTIVITY

• Over the past 40 years, considerable data have
  been accumulated on the beneficial physiological
  effects from physical activity
• We are now becoming aware what activity does for
  the brain (e.g. it decreases depression slows
  cognitive decline in Alzheimer's)

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PROMOTING ACTIVITY

• Activity should be done early and often
  parents can have the largest effect on this in
  infancy
• In addition to physical changes, personality,
  cognitive social development may also be
  affected by early activity (or lack thereof)

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Activty-Based Exercise Programs

• Catch-22 Those with CP need intense exercise to
  improve motor function, but they lack the motor
  function to exercise intensely.
• Therapeutic approach Use of devices that force
  or enable person to exercise beyond their
  voluntary capabilities
• Body-weight supported treadmill training
• Lokomat and other motor driven gait devices
• FES and motor-assisted cycles

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RANDOMIZED TRIAL OF TREADMILL TRAINING IN
INFANTS WITH DOWN SYNDROME (Ulrich
DA, Ulrich BD, Angulo-Kinzler RM, Yun J 2001)
Description 30 infants with DS assigned to
control or home treadmill training beginning at
independent sitting. Followed until onset of
independent walking.
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RESULTS
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Review of BWSTT in Pediatric Rehabilitation
(Damiano DeJong, 2008 in press)

• Shown to be efficacious (RCT) in Down Syndrome to
  accelerate motor milestone acquisition more
  intense training seems to increase activity
  levels at 2 years
• Pediatric SCI prolonged training in a few
  individual cases with impressive anecdotal
  results in most (children can be taught to step
  even if they cannot move voluntarily)
• CNS impairments 17 studies (no RCT) suggesting
  that this improves gait speed and GMFM DE. No
  comparison to alternatives (e.g. over ground
  training)

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RESULTS BWSTT ICF ACTIVITY
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Potential Benefits of Treadmill Training in CP

• Strengthen anti-gravity muscles (by adjusting BWS
  or adding weights)
• Increase gait speed (gt belt speed)
• Improve gait symmetry (e.g. elongating shorter
  strides)
• Improve interlimb coordination (through
  appropriate sensory inputs practice)
• Increase endurance aerobic training)
• Combinations of above

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Motor-Assisted Cycling

• BWS treadmill training labor cost intensive,
  difficult for therapist/ family
• External assistance needed for those who cannot
  cycle on their own due to paresis or lack of
  motor control (FES-cycles or new motor assist
  devices)
• Cycling can be performed in home with little or
  no assistance, trunk balance or WS
• Form of locomotion similar in phasing frequency
  to walking (Ting, 2002)
• Evidence of shared neural circuitry similar
  reflex modulation in walking cycling (Brooke
  1997)

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Current Cycling Trial

• PARTICIPANTS 10 children w/ CP, ages 5-17,
  GMFCS III/IV
• PROTOCOL All perform 50RPM passive or
  active-assisted cycling 30 min/day for 5
  days/week X 3 mos
• GOAL improve lower extremity coordination
• PRIMARY OUTCOMES Changes in comfortable as
  fast as possible cadence, variability in
  cadence, EMG reciprocation vs. synchronization
• SECONDARY OUTCOMES 1) changes in spasticity 2)
  Changes in cortical activation in response to a
  sensory stimulation using fMRI none able to be
  still enough

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Case study from motor-assisted cycling study

• 5 ½ yo boy with spastic diplegia
• GMFCS III ambulates w/ post walker
• Ashworth 3 (0-4) in quadriceps hamstrings
  (strong catch in first half of motion)
• Had adapted cycle, but needed assist from parents
  to ride
• He was able to cycle with the device part of the
  time (no resistance)

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Cortical Plasticity

• The brain is also use-dependent
• Dramatic changes in the PNS produce dramatic
  changes in brain (e.g. SCI amputation)
• Spinal circuits can be accessed and trained
  effects may be specific and localized
• Spinal circuits may be used to drive cortical
  changes that may be more generalized
• How do we help the brain recover?

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What type of activity does brain like?

• Intense (amount, speed, mm activation)
• Some imposed rhythm but variable (more neural
  control)
• Complex or interesting solving problems
• Electrical stimulation (other sensory
  stimulation)
• Locomotor training (loading/ proprioceptive
  input)

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Conclusions

• Those with motor disorders need to be active
  their whole life to minimize negative plasticity
  in mm (e.g. atrophy) optimize positive
  plasticity (e.g. gtfiber size)
• Increasingly obvious that we have been
  under-rehabilitating people with CP other motor
  disorders
• Potential for exercise and activity to restore
  neural function and connectivity just beginning
  to be realized, Muscle activation (electrical
  activity) appears necessary to drive cortical
  plasticity

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THANK YOU
NIH CLINICAL CENTER