Neural Facilitation of Movements in People With SCI

Spinal cord injury leads to long-lasting paralysis and impairment. Re-enabling movement of paralyzed areas is challenging and more information is needed about neurological recovery. The purpose of this study is to understand the contribution of individual neural tracts to movements facilitated by transcutaneous spinal cord stimulation (SCS).

Spinal cord injury leads to long-lasting motor impairment and paralysis that currently is not "curable". Electrical spinal cord stimulation (SCS) is beginning to be used as a neuromodulation technique to re-enable movement of paralyzed areas, however the mechanisms of neurorecovery induced by electrical neuromodulation of the spinal cord remain poorly understood. The goal of this project is to generate evidence-based knowledge of changes in the short-term excitability of corticospinal and reticulospinal neural structures that may mediate immediate improvements in motor function enabled by SCS. The proposed study will: (1) determine which kinds of SCS-facilitated movements are mediated by the corticospinal tract. (2) determine which kinds of SCS-facilitated movements are mediated by the reticulospinal tract. Having a better understanding of the neural mechanisms that are enhanced by SCS can allow the development of therapies that directly target the excitability and plasticity states of these structures towards improved and accelerated recovery.

Eligibility Criteria:
Inclusion Criteria:

Healthy volunteers

* Age between 16-65
* Healthy individuals with no major conditions of any organ system

Exclusion Criteria:

Healthy volunteers

* Not willing or able to provide consent
* Any acute or chronic pain condition
* Any acute or chronic disease of a major organ system
* Use of analgesics within 24 hours prior to study appointment
* Use of caffeine with 3 hours of study appointment
* History of epilepsy
* Implanted metal
* Active medical problems

Inclusion criteria:

Participants with spinal cord injury (SCI)

* Age between 16-65
* Traumatic SCI C4-T9 level, complete (ASIA A) or incomplete (ASIA B, C or D)
* at least 1 year post injury
* Stable medical condition
* difficulty independently performing leg movements in routine activities
* able to follow simple commands
* able to speak and respond to questions

Exclusion criteria:

Participants with spinal cord injury (SCI)

* Not willing or able to provide consent
* Any acute or chronic pain condition
* Any acute or chronic disease of a major organ system
* Use of analgesics within 24 hours prior to study appointment
* Use of caffeine with 3 hours of study appointment
* Presence of tremors, spasms and other significant involuntary movements
* Etiology of SCI other than trauma
* Concomitant neurologic disease such as traumatic brain injury (TBI) that will significantly impact the ability to follow through on study directions, multiple sclerosis (MS), stroke or peripheral neuropathy)
* History of significant medical illness (cardiovascular disease, uncontrolled diabetes, uncontrolled hypertension, osteoporosis, cancer, chronic obstructive pulmonary disease, severe asthma requiring hospitalization for treatment, renal insufficiency requiring dialysis, autonomic dysreflexia, etc).
* Severe joint contractures disabling or restricting lower limb movements.
* Unhealed fracture, contracture, pressure sore, urinary tract infection or other uncontrolled infections, other illnesses that might interfere with lower extremity exercises or testing activities
* Depression, anxiety, or cognitive impairment
* Deficit of visuo-spatial orientation
* Sitting tolerance less than 1 hour
* Severe hearing or visual deficiency
* Miss more than 3 appointments without notification
* Unable to comply with any of the procedures in the protocol
* Botulinum toxin injection in lower extremity muscles in the prior six months
* Any passive implants (osteosynthesis material, metallic plates or screws) below T9.
* Any implanted stimulator in the body (pacemaker, vagus nerve stimulator, etc.)
* History of alcoholism or another drug abuse
* Pregnancy (or possible pregnancy)
* Having an Intrathecal Baclofen Therapy Pump (ITB pump)
* History of epilepsy