Roadmap: Neuroplasticity - sbahc.org.sasbahc.org.sa/ISCIC_Sessions_2014/ISCIC_session2/S2.1 Edelle...
Transcript of Roadmap: Neuroplasticity - sbahc.org.sasbahc.org.sa/ISCIC_Sessions_2014/ISCIC_session2/S2.1 Edelle...
1
Neuroplasticity in Recovery After SCI:
optimizing recovery through
rehabilitation interventions
Edelle C. Field-Fote, PhD, PT, FAPTA
Professor, Physical Therapy & Neurological Surgery
Principal Investigator, The Miami Project to Cure Paralysis
INTERNATIONAL SPINAL CORD INJURY CONFERENCE:
TOWARD BETTER QUALITY OF LIFE
Roadmap:
1. What neural mechanisms underlie
neuroplasticity?
2. What happens in the brain following CNS
injury and can we reverse these changes?
3. How can we use this information to
promote upper extremity function?
4. What is the innate capacity of spinal circuits
and do they respond to training?
5. Is there an optimal approach to improving
walking function?
Neuroplasticity
• The capacity of the CNS to undergo
changes in function and structure in
response to use and motor learning
• May be favorable or unfavorable
2
neural excitability influences responsiveness
Kandel, Schwartz & Jessell, Principles of Neural Science, 2000
Spinal
motoneuron
Modified from Asanuma & Mackel Jpn J Physiol, 1989.
Sensory input influences the
motor cortex
Roadmap:
1. What neural mechanisms underlie
neuroplasticity?
2. What happens in the brain following CNS
injury and can we reverse these changes?
3. How can we use this information to
promote upper extremity function?
4. What is the innate capacity of spinal circuits
and do they respond to training?
5. Is there an optimal approach to improving
walking function?
The cortex reorganizes
after SCI…
Green et al. Neurology, 1998
…does this contribute
to functional deficits?
3
Cortical excitability is increased with
sensory stimulation
Pre MEP Post MEP
Ridding et al, Exp Brain Res, 2000
Roadmap:
1. What neural mechanisms underlie
neuroplasticity?
2. What happens in the brain following CNS
injury and can we reverse these changes?
3. How can we use this information to
promote upper extremity function?
4. What is the innate capacity of spinal circuits
and do they respond to training?
5. Is there an optimal approach to improving
walking function?
Hand function is highest priority
among those with tetraplegia
Anderson K. J Neurotrauma, 2004
Gross UE Movement
Pinch
Pinch with rotation Grip with rotation
Grip
Massed practice for task-specific
training effects
Beekhuizen & Field-Fote. Arch Phys Med Rehabil, 89: 602-608, 2008
4
Somatosensory Stimulation Parameters
• 2 hrs/day
• median nerve stimulation (at wrist)
• Either:
– in conjunction with MP training (MP +SS)
– or alone (SS)
• Parameters: trains of stimulation
– 10 Hz (500ms on / 500 ms off)
– 1 msec pulse duration
– Submotor threshold intensity
• (no visible thumb contraction)
• Goal:
– Preferentially activate large proprioceptive
and cutaneous sensory fibers
stimulating electrode
over median nerve
(recording electrodes over
thenar eminence)
Ridding et al. Exp Brain Res, 2000 (ND)
Conforto et al. Ann Neurol, 2002 (Stroke)
Outcome Measures
10 measure: Jebsen-Taylor Hand Function Test
Electrophysiologic (MEPs):
• AMT thenar
• RMT biceps (to determine rTMS frequency)
• Recruitment Curve thenar (active contraction)
20 Measures
Functional measures
• Pinch Grip Strength
• 9-Hole Peg Test
What approach is best for improving
motor & sensory function?
Beekhuizen &Field-Fote . Arch Phys Med Rehabil, 2008
Jebsen-Taylor Hand Function Test Monofilament Sensory Testing
% Change (pre-post)
Pre training Functional Test
5
Post training Functional Test Change in hand function is associated
with change in excitability
Pre-training
Post-training
Sample thenar MEP at 88% MSO
Co
rtic
al M
ap
pin
g
Hoffman & Field-Fote. Phys Ther, 2007
Is direct cortical activation more beneficial
than indirect (somatosensory) activation ?
Available approaches to direct cortical stimulation
– Transcranial direct current stimulation (tDCS)
•Modulates neuronal excitability
•Studies in persons with stroke
– anodal vs cathodal
– Repetitive transcranial magnetic stimulation
•Activates neurons
•Studies in persons with stroke (high frequency)
6
tDCS
Effects on cortical excitability
– Neuromodulator
– Anode=
EXCITATION
– Cathode=
INHIBITION
ANODE CATHODE
(Fregni & Pascual-Leone, 2007)
Hand function in persons with tetraplegia -
effects of direct vs indirect cortical activation
0
0.5
1
1.5
2
2.5
tDCS TENS VIB
9HPT (pegs)
Pinch force (kg)
rTMS in SCI and ND
• High frequency
(excitatory) rTMS
– Direct cortical activation
– Elicits motor response
(Pascual-Leone, 1994; Beradelli et al, 1998; Butefish et al, 2004; Kim et al, 2006;
Tallelli & Rothwell, 2006)
Results:
functional outcomes
Dashed line indicates threshold for moderate effect size
7
Conclusions
• Both direct and direct cortical
activation augments training effects
• Stimulation choices depend on:
– Device availability
– Clinic vs home use
Roadmap:
1. What neural mechanisms underlie
neuroplasticity?
2. What happens in the brain following CNS
injury and can we reverse these changes?
3. How can we use this information to
promote upper extremity function?
4. What is the innate capacity of spinal circuits
and do they respond to training?
5. Is there an optimal approach to improving
walking function?
The spinal cord can coordinate the limbs
following complete spinal cord transection
Field & Stein. J Neurophysiol. 1997; 78: 1394-1403 and 1404-1413
Infant Stepping Response
evidence of central pattern generators in humans
8
Roadmap:
1. What neural mechanisms underlie
neuroplasticity?
2. What happens in the brain following CNS
injury and can we reverse these changes?
3. How can we use this information to
promote upper extremity function?
4. What is the innate capacity of spinal circuits
and do they respond to training?
5. Is there an optimal approach to improving
walking function?
TS
OG LR
Locomotor training improves walking in SCI
– is there a “best” approach?
• Treadmill training with manual
assistance (TM)
• Treadmill training with CPN
stimulation assist (TS)
• Overground training with CPN
stimulation assist (Walkaide II
stimulator; OG)
• Treadmill training with robotic
assistance (Lokomat robotic
orthosis; LR)
TM
Field-Fote & Roach. Phys Ther, 91:48-60, 2011
N = 74 enrolled, 64
completed (across 4 groups)
Note: Robotic Orthosis
used in Passive Mode Only
Changes in Walking Speed
by Intervention Group
Sp
eed
(m
/s)
Walking speed in ND individuals is 1.2 m/s (2.7mph)
Field-Fote & Roach. Phys Ther, 91:48-60, 2011
9
Changes in Walking Distance
by Intervention Group
Sp
eed
(m
/s)
Field-Fote & Roach. Phys Ther, 91:48-60, 2011
Whole-body vibration decreases
spasticity and improves
walking in persons with SCI
Excitability in response to
stretch can be quantified
The Pendulum
T
est
Hig
h spastic
ity Lo
w spastic
ity
WBV is associated with improved
gait speed and quality
Ness & Field-Fote. Gait & Posture, 2009
10
How might vibration influence
the locomotor CPG?
Vibration elicits involuntary step-
like movement in ND individuals
•Vibration elicits locomotor-like movements
•Single muscle or contralateral leg
•Cyclic behavior suggesting CPG origin
Gurfinkel et al. Eur J Neurosci, 10:1608-1612, 1998
Vibration elicits involuntary stepping in
individuals with SCI
Vibration: 60 Hz, ~1 mm displacement
ND Individual: Involuntary Stepping with
Muscle Vibration
Field-Fote et al, Neurorehabil Neural Repair. 2012
11
Motor-incomplete SCI: Involuntary Stepping
with Muscle Vibration
Field-Fote et al, Neurorehabil Neural Repair. 2012
Motor-complete SCI: Involuntary Stepping
with Muscle Vibration
Field-Fote et al, Neurorehabil Neural Repair. 2012
Conclusions & Considerations
1. Neural mechanisms underlying
neuroplasticity rely on changes in
excitability
2. Neural excitability is influenced by
practice and by stimulation
3. Combining training and stimulation may
represent an optimal approach to
promoting adaptive neuroplasticity
For the future:
Repair strategies are likely to be effective
only when combined with rehabilitation
strategies
The BAD News:
To Date No Intervention has been shown to be More Effective than Rehabilitation
for Improving Function
The GOOD News:
To Date No Intervention has been shown to be More Effective than Rehabilitation
for Improving Function
REPAIR
REHABILITATION
+
12
● National Institutes of Health ● The Schumann Foundation
● The Buoniconti Fund ● National Institute for Disability &
● Craig H. Nielsen Foundation Rehabilitation Research
PRIMARY
SPONSORS WBV influences on spasticity
• cumulative multi-session effects
• early within-session effects
• late within-session effects
FS
E (
deg
rees)
Intervention week
Ness & Field-Fote. Restor Neurol Neurosci, 2009
Early vs Late Effects on Cortical Excitability
Rationale:
unilateral arm use is associated
with inhibition of the inactive cortex
INHIBITION↓ EXCITATION↑
(Mc Combe & Waller, 2008)
ACTIVE
CORTEX
(UNI)
INACTIVE
CORTEX
(UNI)
BILATERAL BASELINE
but…
13
bilateral arm use is associated with
bihemispheric excitation
(Mc Combe & Waller, 2008)
BILATERAL BASELINE ACTIVE
CORTEX
(UNI)
INACTIVE
CORTEX
(UNI)
EXCITATION↑ EXCITATION↑
Field &Stein. J Neurophys, 1997
The spinal cord controls limb coordination
of innate, rhythmic behaviors
Bimanual typing task interface
N = 28 ND participants
Safety Study: Bihemispheric
Anodal tDCS Results
Mean change in scores BE-tDCS: 19.4 (95% CI 12.82-25.99)
Mean change in scores sham: 12.5 (95% CI 7.6-17.3)
14
Conclusions in ND subjects
• tDCS yields greater gains in manual
performance versus practice alone.
• No effects on short term memory