Combining Spinal Cord Transcutaneous Stimulation and Activity-based Training in Inpatient Rehabilitation to Facilitate Upper Limb Function of Individuals with Acute to Subacute Cervical Spinal Cord Injury

The purpose of this clinical trial is to understand the safety and practicality of using spinal cord transcutaneous (through the skin) stimulation in an inpatient setting as well as how the combination of activity-based training (ABT) and spinal cord transcutaneous stimulation (scTS) can improve participants' ability to use their hands, arms, and trunk in an inpatient rehabilitation program. The main questions it aims to answer are:

* Is the combination of spinal cord transcutaneous stimulation and ABT is safe and practical when applied to individuals with acute to subacute cervical SCI during inpatient rehabilitation?
* How the combined intervention can improve hand and arm function when applied to those individuals? The investigators will assess the safety, feasibility, and preliminary efficacy of the combined intervention and compare to a sham control (sham stimulation combined with ABT) and a ABT only group to see if the combined intervention can lead to greater function recovery.

Participants will:

* Receive one type of the three intervention (scTS+ABT, sham scTS+ABT, or ABT only) for 10 sessions with 30 mins/session over 2 weeks.
* Receive assessment before, during, and immediately after the intervention, and at 1-month, 2-month, and 3-month follow-up visits.

The objective of this study is to investigate the use of scTS combined with ABT in inpatient rehabilitation, to facilitate UE functional recovery for individuals with acute to subacute cervical SCI. The investigators will assess the safety, feasibility, and preliminary efficacy of the combined intervention with a 10-day regimen in a randomized, sham-controlled clinical trial. The investigators hypothesize that the combination of scTS+ABT applied in individuals with acute to subacute cervical SCI will 1) be both safe and feasible when implemented as a part of the medical care in an inpatient SCI rehabilitation program, and 2) promote greater improvements in UE function compared to sham control and ABT alone. In addition, the investigators will explore the potential neurophysiological mechanism underlying the combined intervention by evaluating the pre-post changes of cortical and spinal excitability. The investigators anticipate that the functional outcome improvements will be associated with the gains of cortical and spinal excitability.

(Aim 1) To determine whether scTS+ABT intervention is safe when applied to persons with acute to subacute cervical SCI during inpatient rehabilitation. The investigators will evaluate the intervention safety based on the adverse event reports focusing three categories: (1) scTS-related (pain/discomfort and skin integrity), (2) ABT-related (musculoskeletal injuries, heart rate, and oxygen saturation levels), and (3) SCI-related (spasticity and autonomic dysreflexia). The type, frequency, and severity of adverse events reported in scTS+ABT group will be compared to those from ABT alone group. (Aim 2) To examine whether a 10-day regimen of scTS+ABT is feasible to apply to individuals with acute to subacute SCI during an inpatient rehabilitation program. The interest and willingness of participants to enroll and complete this study will provide insight into the feasibility of scTS+ABT intervention. The investigators will assess the feasibility based on quantitative data including ease of recruitment (accrual rate) and study completion rate and compare the study completion rate in scTS+ABT and ABT alone group. (Aim 3) To evaluate the efficacy of scTS+ABT intervention in promoting UE functional recovery in acute to subacute SCI, as compared to the sham control and ABT only. Given the greatest opportunity for recovery and neuroplasticity in acute-subacute SCI stage and the promising results demonstrated in the previous chronic SCI studies, the investigators expect that applying scTS+ABT at early stages would lead to greater UE function improvements compared to scTSsham+ABT and ABT only. UE motor impairment, voluntary handgrip strength, and UE functional ability will be quantitatively assessed three time at baseline, once at the end of intervention, and once at 1-, 2-, 3-month follow up. Within-group and between-group comparison will be made to evaluate the efficacy of different interventions. (Aim 4, Exploratory) To quantify and characterize the neurophysiological changes after scTS+ABT, as compared to the sham control or ABT alone. Previous chronic studies have suggested that scTS can increase the excitability of spinal network and activate the motor neurons within spinal cord distal to the lesion, leading to restoration of voluntary motor control. Here, the investigators will examine whether a 10-day regimen of scTS+ABT applied in the acute to subacute stage can also lead to neurophysiological gains. Pre-post changes in the cortical and spinal excitability will be measured and compared to the sham control and ABT only group. As an exploratory aim, the investigators will evaluated on a subset sample of each group (n=4).

Eligibility Criteria:
Inclusion Criteria:

* must be at least 18 years of age.
* must have had a spinal cord injury for less than or equal to 8 weeks.
* must have a traumatic cervical SCI with lesions (AIS A or B, C5-C7).
* must have some degree of motor dysfunction in the hand (bilateral UE motor score \<25).
* must be medically stable enough to participate in activity-based recovery training.
* must be able to tolerate spinal cord transcutaneous stimulation, as determined by study staff.
* must have ability to understand and the willingness to sign an informed consent.

Exclusion Criteria:

* have a history of seizures, head trauma and/or cognitive deficit
* have surgically implanted foreign bodies such as a pacemaker, metal plate in the skull, and metal inside the skull
* have a pressure sore or skin issues.
* have severe spasticity.
* in medically unstable condition.
* have a history of illicit drug abuse.
* have a history of medical disorders of my heart, lungs, bladder, kidneys or other parts of my body that are unrelated to my spinal cord injury.
* unable or unwilling to wean from anti-spasticity medication (for an example: baclofen, Xeomin, and Lioresal).
* unable to meet the attendance requirements.
* currently enrolled in another interventional research study.
* unable to follow instructions and maintain alertness during assessments and training.