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Motor Systems: Proof of Principle



Spinal Epidural Electrode Array to Facilitate Standing and Stepping in SCI

Susan Harkema, Ph.D, Yuri Gerasimenko, Ph.D., Jonathan Hodes, M.D., Joel Burdick, Ph.D., Claudia Angeli, Ph.D, Yangsheng Chen, Ph.D, Christie Ferreira, Andrea Willhite, Enrico Rejc, Ph.D., Robert G. Grossman, M.D., Reggie Edgerton, Ph.D.

Fig 1 is Radiographic and clinical characteristics of subject with motor complete, but sensory incomplete SCI.
a)  T2 weighted sagittal Magnetic Resonance Image of cervical spine at subject’s injury site (C7-T1). Hyperintensity and myelomalacia noted at site of injury.
b)  AIS evaluation of the subject.




Note that the implant is not at the injury site.
Localization of electrode array relative to motoneuron pools as identified with motor evoked potentials during surgical implantation.
a) Post-operative fluoroscopy of the thoracolumbar spine showing the location of the implanted electrode array and neurostimulator.
b) Depiction of 16-electrode array configuration relative to spinal dorsal roots and corresponding motoneuron pools identified using EMG recorded from leg muscles.
c and d) Motor evoked potentials elicited using epidural stimulation at 2 Hz, 210 µs from 0.0 to 7 V with rostral electrodes, (5- : 6+) and caudal electrodes (10- : 9+) respectively. Muscles: IL: iliopsoas, AD: adductor magnus, VL: vastus lateralis, MH: medial hamstrings, TA: tibialis anterior, GL: gluteus maximus, SL: soleus, MG: medial gastrocnemius.


Whole Body Systems Neuromodulation

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Cardiovascular and Respiratory


Proof of Principle

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Bladder, Bowel, and Sexual Function


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Before implant is placed in the subject, the subject goes thru Locomotor Training including:

  • Stand and step training
  • Body weight support

  • manual assistance

There are Three time points over  two year period; during the pre-training subject has had:

  • Zero sessions for the first period;
  • 66 sessions in the second period; and finally
  • 170 sessions in the last period.



EMG activity with sc-ES during independent standing

The output of the spinal circuitry can be sufficiently modulated by the proprioceptive input to sustain independent standing
EMG activity increases in amplitude and becomes more constant bilaterally in most muscles with independent standing occurring at 8 V.

Reducing BWS changed the EMG amplitudes and oscillatory patterns differently among muscles .

(15Hz) (4/10/15- : 3/9+)
1 – 8V and 65% BWS
8V BWS from 45% to 5%.


(8 V,15 Hz) (4/10/15- : 3/9/14+)


Sensory Information modulates Lower extremity EMG activity during standing and stepping with body weight support and manual facilitation during sc-ES of caudal lumbosacral segments.