Using Non-invasive Brain and Spinal Cord Stimulation to Improve Arm and Hand Function After Spinal Cord Injury

Combining Non-invasive Brain and Spinal Cord Stimulation for Improving Arm and Hand Function Following Spinal Cord Injury.

Cervical spinal cord injury (SCI) disrupts communication between the brain and spinal circuits, affecting voluntary movement control and contributing to arm and hand impairments, the top recovery priority for people with tetraplegia. Although rehabilitation and emerging neuromodulation approaches can support meaningful gains, many individuals experience persistent limitations in reaching and grasping. Current noninvasive stimulation strategies typically target the brain OR the spinal cord alone, despite strong reciprocal interactions between these structures. Cervical transcutaneous spinal cord stimulation (tSCS) can enhance upper limb function. Cerebellar stimulation, given its key role in sensorimotor integration and modulation of corticospinal excitability, represents a promising but underexplored therapeutic target. Theta burst stimulation (TBS), a rapid form of repetitive transcranial magnetic stimulation (TMS), induces lasting changes in cortical excitability and may promote associative plasticity when paired with spinal cord stimulation. This double-blind, randomized, sham-controlled pilot trial (n=24) will evaluate the feasibility, preliminary efficacy, and mechanisms of combined cerebellar TBS + cervical tSCS in people with chronic cervical SCI (AIS B, C or D). Participants will either receive cerebellar TBS + cervical tSCS, tSCS only, or sham stimulation while engaging in functional task practice such as pinching and grasping 3x/week for 8 weeks. Feasibility outcomes include adherence, retention, and safety. Efficacy will be assessed using the GRASSP strength sub-score and KINARM-based measures of sensorimotor control. Mechanistic outcomes will assess changes in cortical and spinal cord functional connectivity using resting state fMRI, corticospinal excitability using motor evoked potentials, and spinal excitability using the H reflex. Findings will establish whether combined cerebellar TBS and cervical tSCS is feasible, safe, and capable of enhancing upper limb recovery.

Inclusion Criteria:

1. At least 19 years of age and no older than 75 years at the time of enrollment. Previous research has demonstrated the safety and efficacy of stimulation-based interventions in adults up to 75 years of age. The lower age limit reflects the legal age for independent informed consent in British Columbia.7,8
2. Non-progressive cervical SCI from C2-C8 inclusive
3. AIS classification B, C or D
4. Indicated for upper extremity training procedures by the participant's treating physician, occupational therapist, or physical therapist
5. GRASSP-Prehension score ≥10 or GRASSP-Strength score ≥30
6. Minimum 12 months after injury (i.e., chronic SCI)
7. If prescribed anti-spasticity or pain medications, must be at a stable dose for at least 4 weeks before commencing study procedures
8. Stable management of spinal cord related clinical issues (e.g., spasticity management, autonomic dysreflexia)
9. Capable of providing informed consent

Exclusion Criteria:

1. Has any unstable or significant medical condition that is likely to interfere with study procedures or likely to confound study endpoint evaluations, such as severe neuropathic pain, depression, mood disorders or other cognitive disorders
2. Has been diagnosed with autonomic dysreflexia that is severe, unstable and uncontrolled
3. History of additional neurologic disease, such as stroke, multiple sclerosis and traumatic brain injury
4. History of seizures (e.g. epilepsy).
5. Any implanted metal (other than dental implants) in the skull or presence of pacemakers, stimulators, or medication pumps in the trunk.
6. Participant has undergone electrode implantation surgery.