BRAIN PLASTICITY AFTER SPINAL CORD INJURY CORTICAL REORGANIZATION AFTER CHRONIC SCI

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BRAIN PLASTICITY AFTER SPINAL CORD
INJURYCORTICAL REORGANIZATION AFTER CHRONIC SCI

• Mar Cortes
• Non-invasive Brain Stimulation and Human Motor
  Control Lab
• Burke Medical Research Institute
• Cornell University
• New York

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SCI PHASES AND KEY PATHOLOGICAL EVENTS
Rowland et al, Neurosurg Focus, 2008
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STRATEGIES FOR SPINAL CORD REPAIR Multiple
systems affected - multivariety of approaches

• Prevention of injury
• Reduction of secondary damage
• Replacement of lost cells
• Strategies to enhance regeneration
• The development of new circuitry/ rehabiliation
  of remaining circuitry

• Neurophysiology to understand the underlying
  mechanisims of dysfunction
• Neuromodulation - to enhance cortical/spinal cord
  excitability
• Training therapies - to enhance/repair motor
  function

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BRAIN NETWORKS INVOLVED IN MOTOR CONTROL REMAIN
RESPONSIVE IN CHRONIC PARALYSIS
Healthy Subject
SCI Patient
5/5
Motor Power
1/5
MEP at 110 RMT
Edwards et al, in preparation
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Transcranial Magnetic Stimulation Mapping
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REORGANIZATION AND PRESERVATION OF MOTOR CONTROL
OF THE BRAIN IN SCI
Kotilo et al, J Neurotrauma (2011)
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CORTICOMOTOR REPRESENTATION OF FOREARM MUSCLES
FOLLOWING CERVICAL SCI

• AIM Investigate changes in cortical map
  reorganization of forearm muscles with lack of
  voluntary activation but corticospinal response
  in chronic SCI non-invasively
• Preservation of corticospinal responses of
  impared muscles
• Changes in somatotopic localization
• Differences in map area and volume compared with
  healthies
• SIGNIFICANCE Therapeutic strategies aiming for
  restoring spinal cord function even with chronic
  sci can build on a preserved competent brain
  control

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CORTICAL REORGANIZATION AFTER CHRONIC SCI
PATIENT GENDER AGE LEVEL OF INJURY ASIA TYPE TIME SINCE INJURY MUSCLE SIDE MOTOR POWER
1 F 29 C4 B 2.3 FCR L 1
2 M 31 C5 B 7.5 FCR L 1
3 M 44 C4 C 1.8 ECR R 1
4 F 55 C5 A 2.1 FCR R 1
5 M 54 C6 A 2.2 FCR R 1
6 M 70 C1 D 3 ECR R 1
7 F 24 C4 B 5.8 ECR L 1
8 M 17 C4 B 4 ECR R 1
9 M 50 C6 A 29 FCR L 0
10 M 50 C1 C 3 ECR L 1
Presence of MEP gt 100uV in forearm muscle, with
normal latency range. Motor Power of forearm
muscle 0-1/5. Chronic SCI (gt1year after injury).
Cervical injury. Tetraplegic. Traumatic/non-trauma
tic. Complete/Incomplete
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CORTICAL REORGANIZATION AFTER CHRONIC
SCIOPTIMAL SITE LOCATION OF FOREARM MUSCLES
Right hemisphere
Left hemisphere
Cz
Cortes et al, in prep
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CORTICAL REORGANIZATION AFTER CHRONIC SCI
MEDIAL SHIFT OF THE OPTIMAL SITE IN SCI SUBJECTS
Right hemisphere
Left hemisphere
Cz
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EMG BIOFEEDBACK MUSCLE SPECIFIC TRAINING RESTORES
NEUROPHYSIOLOGICAL VALUES IN CHRONIC SCI
SCI pre training
SCI post training
Healthy subject
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CONCLUSIONS

• TMS GUIDED REHABILITATION
• Muscles that are profoundly affected after SCI,
  can be identified by TMS
• GREATER POTENTIAL FOR RECOVERY
• Muscles with corticospinal response to TMS,
  despite being clinically silent, may have
  biological substrate for functional enhancement,
  even in chronic phase
• CORTICAL REORGANIZATION AFTER CHRONIC SCI
• - Changes in cortical organization occurs after
  SCI
• - Clinically silent muscles in tetraplegic
  patients have a medial shift cortical
  representation, in the direction of the
  deafferented lower limb
• - The understanding of the cortical
  reorganization after chronic SCI may have
  implications for function recovery, by using
  therapeutic strategies that specifically target
  that brain area (brain stimulation protocols)

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Neuromodulation to enhance spinal excitability
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Peripheral stimulation of somatosensory afferents
conditioned by TMS, increases spinal
excitability, traduced in a larger H-reflex
amplitude
TMS
TMS80RMT Only
PNS
PNS Only
TMS
PNS
20ms
Combined TMS80RMTPNS
Cortes et al, Clin Neurophys, 2011
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Neuromodulation paradigm to modulate spinal
excitability Spinal Associative Stimulation
protocol
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Repetitive paired stimulation can induce changes
in excitability at the spinal cord level that are
sustained after the intervention period
H-reflex recruitment curve
H-reflex amplitude progressively increased over
the paired pulse intervention period
Left shift of the H reflex RC after the
intervention period, with a lower threshold
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CONCLUSIONS

• Non-invasive Brain Stimulation can be used as a
  neuromodulatory tool to target spinal cord and
  induce changes and enhance excitability at that
  level
• SAS may be useful to strength residual pathways
  after incomplete injuries.
• SCI plastic changes outlast intervention period
  gt therapeutic window to apply behavioral
  training in order to enhance motor recovery

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FUTURE CONSIDERATIONS TO ENHANCE MOTOR RECOVERY
AFTER SCI
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ACKNOWLEDGEMENTS
Dylan J Edwards Raj Ratan Bruce Volpe Avrielle
Rykman Alvaro Pascual-Leone Gary
Thickbroom Josep Valls-Sole
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Thank you
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Chronic SCI motor performance after Upper limb
Robotic Training
Pre training
Post - training