Transcutaneous Auricular Vagus Nerve Stimulation as a Treatment for Neuropathic Pain Following Spinal Cord Injury

Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) as an Anti-inflammatory Strategy for the Treatment of Neuropathic Pain Following Spinal Cord Injury

This pilot randomized, double-blind, sham-controlled clinical investigation will evaluate the feasibility and safety of a 30-day home-based transcutaneous auricular vagus nerve stimulation (taVNS) intervention in adults with spinal cord injury (SCI) and neuropathic pain. Participants will be randomized to receive either active taVNS targeting the auricular branch of the vagus nerve or sham taVNS delivered to the earlobe. Primary outcomes include feasibility, safety, adherence, acceptability, and blinding success. Exploratory outcomes include changes in neuropathic pain, systemic inflammatory biomarkers, vagal tone assessed via heart rate variability, and quality of life.

Neuropathic pain is a common and debilitating complication following spinal cord injury (SCI) and is frequently resistant to pharmacologic treatment. Chronic neuroinflammation and reduced vagal tone are increasingly recognized contributors to persistent neuropathic pain after SCI. The vagus nerve plays a central role in immune regulation and descending pain modulation.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive neuromodulation technique that stimulates vagal afferent fibers via the external ear. Prior Health Canada-authorized trials conducted by the investigative team have demonstrated the feasibility, safety, and autonomic effects of taVNS in individuals with SCI.

This single-site, randomized, double-blind, sham-controlled pilot study will enroll 32 adults with SCI and neuropathic pain. Participants will be randomized 1:1 to receive either active or sham taVNS for 4 hours per day over a 30-day home-based intervention period. Outcomes will be assessed at baseline and immediately post-intervention. Feasibility and safety outcomes are primary, while exploratory clinical and mechanistic outcomes will inform the design of a future definitive randomized controlled trial.

Inclusion Criteria:

• SCI of any level or severity
• 18 years of age or older
• current neuropathic pain
• on no medications or on a stable prescribed dose (no change in prior 6-weeks) of anti-inflammatory, pain medications and/or depression medications

Exclusion Criteria:

• Prone to autonomic dysreflexia
• presence of cardiovascular disease
• pacemaker or other implanted electrical device
• cerebral shunts
• epilepsy
• pregnant or attempting to become pregnant
• current wound/infection
• unstable dose of prescribed anti-inflammatory, depression, or pain medications within past 6-weeks.