Title: Activity in Cerebral Palsy: How it helps muscles
1Activity in Cerebral PalsyHow it helps muscles
( brains!)
Diane L. Damiano, PhD PT National Institutes of
Health Bethesda MD USA
2TAKE HOME MESSAGE
- Activity,
- Activity,
- Activity.
3 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
4Step Counts in CP by GMFCS LEVEL vs. Peers
(Bjornson et al 2007)
5Outline
- 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
6- 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
7Muscle 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.
8How 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) -
9How 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
10Muscle 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
11What 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?
12What 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
13Strength in CP vs. Non-CP Dominant Side
(Wiley Damiano, DMCN 1998)
14Non-Dominant Side
15Strength by GMFCS Level
16Muscle 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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20Muscle 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
21Methods
- 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
22Methods
- Computed slope of the decline in torque
(normalized to peak torque) in the quadriceps
hamstrings mms
23Results for the Quadriceps
24Correlation of Slope GMFCS
Spearman (r) -0.50, p .035
25RESULTS
- 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?
-
26FATIGUE 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 -
-
27In Vivo Evidence of Muscle Plasticity
28THIGH CT SCANS IN TWO MATCHED PATIENTS WITH
COMPLETE SCI (n56)
TRADTIONAL PT CONTROL 6
MOS. OF FESCYCLING
(Sadowsky, McDonald, Damiano et al)
29Introduction 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
30RECTUS FEMORIS 3D US
Longitudinal ?
RF
Axial ?
31Relationship 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.
32MUSCLE THICKNESS IN ADULTS WITH CP (Ohata et al,
Phys Ther 2006)
BY STANDING ABILITY
BY GMFCS LEVEL
33Muscle 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
34Relationship of Muscle Thickness to Peak Torque
VL MT (mm)
ISOMETRIC PEAK TORQUE (N.m)
p lt 0.05 p lt 0.01
35Rectus Femoris Cross-Sectional Areain CP by
GMFCS Level and vs. Control
GMFCS X Normalized Cross-Sectional Area r
0.50, p .05
36RECTUS 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
37CHANGE 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)
38NEUROBIOLOGY 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)
39PROMOTING 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)
40Activty-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
41RANDOMIZED 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.
42RESULTS
43Review 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)
44RESULTS BWSTT ICF ACTIVITY
45Potential 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
46Motor-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)
47Current 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
48Case 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)
49Cortical 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?
50What 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)
51Conclusions
- 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
52THANK YOU
NIH CLINICAL CENTER