Safety and Feasibility of Paired Vagus Nerve Stimulation With Rehabilitation for Improving Upper Extremity Function in People With Cervical Spinal Cord Injury

The current study will evaluate the safety and feasibility of a novel rehabilitation protocol to improve upper limb motor recovery in adults with incomplete cervical SCI. In this double-blinded, randomized, placebo-controlled pilot trial, 8 adults (above 18 years) with cervical SCI will be randomly assigned in a 1:1 ratio to active VNS paired with rehabilitation or control VNS paired with rehabilitation. All participants will be implanted with a VNS device and randomized to receive either active VNS (0.8mA) or control VNS (0.0 mA) paired with upper limb rehabilitation. All participants will receive three 1.5-hour sessions per week for 6 weeks of in-clinic therapy, followed by a daily, 30 minutes home therapy program for 90 days. The rehabilitation therapy involves repetitive, progressive, task-specific exercises adjusted to the participant's functional level. Participants, assessors, and therapists will maintain blinding until the completion of this phase. After 90 days, in phase II, participants in the control VNS group will cross over to receive active VNS paired with rehabilitation. Safety and feasibility measures are the primary outcomes of this study. Safety measures will include the incidence of surgical and VNS therapy-related events. Feasibility metrics include reporting attrition rate and compliance rate with both in-clinic therapy sessions and home exercise programs. To measure efficacy, change in Graded and Redefined Assessment of Strength, Sensibility, and Prehension from baseline to immediately after 6-week in-clinic treatment and 90-day assessment will be analyzed. Additional clinical outcomes include the Toronto Rehab Institute Hand Function Test, Capabilities of Upper Extremity Questionnaire, spinal cord injury independence self-care measure, and spinal cord injury quality of life. The results of this study will provide valuable information on safety and feasibility and insight into the efficacy of pairing VNS with rehabilitation in people with SCI. Knowledge obtained from this study will lay the groundwork for future large randomized control trials to assess the dosing and effectiveness of pairing VNS with rehabilitation.

Inclusion criteria

• a diagnosis of traumatic incomplete (AIS B-D) cervical spinal cord injury (C8 and above)
• at least 12 months post-traumatic SCI
• demonstrate some residual movement in the upper limb (e.g., able to perform pinch movement with thumb and index finger)
• meet all clinical criteria for the surgical VNS implantation as determined by the PI, neurosurgeon, and anesthesiologist.

Exclusion criteria

• non-traumatic SCI, injury
• presence of ongoing dysphasia or aspiration difficulties
• evidence of vagus pre-existing vocal cord paralysis as determined with laryngoscopy procedure
• participants with prior left-sided anterior cervical surgery who exhibit too much of scar tissue at the surgery site which will be determined by neurosurgeon
• concomitant clinically significant brain injury
• history of prior injury to a vagus nerve
• receiving medication that may significantly interfere with the actions of VNS on neurotransmitter systems at study entry
• other comorbidities or complications that will hinder or contraindicate surgical procedure
• medical or mental instability
• pregnancy or plans to become pregnant during the study period.