Compliance During a Vagus Nerve Stimulation Intervention Among Participants with Spinal Cord Injury and Ischemic Stroke

Research Objectives: After neurological injury, continued efforts to improve recovery of function are a priority for patients, clinicians, and researchers alike. Here, we describe the rate and characteristics of compliance with session completion among individuals with spinal cord injury (SCI) and ischemic stroke participating in vagus nerve stimulation (VNS) paired with rehabilitation studies.

Design: Two simultaneous prospective, double-blind, sham-controlled, plus open-label extension clinical trials

Setting: Community setting

Participants: Nineteen individuals with SCI [incomplete tetraplegia, >1 year post injury, age 18-64 years] and 17 individuals with ischemic stroke [>1 year post injury, age 22-79 years] who met all eligibility criteria were enrolled to participate in the study.

Interventions: Participants traveled to a local rehabilitation clinic for 36 rehabilitation sessions. During the initial 18 sessions, participants received either active VNS or sham VNS according to randomization. All participants received active VNS during the final 18 sessions. Sessions were 90 minutes, three times per week, led by a physical therapist and consisted of gamified, individualized exercises targeting upper limb deficits.

Main Outcome Measures: Compliance with session completion was measured by the number of weeks required to complete 36 sessions. The expected timeframe for completion was 12 weeks. Participants who did not complete the sessions within this timeframe were considered “within window” if they required between 13 to 18 weeks and “out of window” if they required 19 or more weeks. Reasons for missed sessions were recorded.

Results: Study completion rate ranged from 12 weeks to 39 weeks among participants. Ten (28%; 4 SCI, 6 stroke) participants completed the study within the expected timeframe of 12 weeks. For participants who required greater than 12 weeks to complete all sessions, 15 (42%; 10 SCI, 5 stroke) participants were “within window” and 11 (30%; 5 SCI, 6 stroke) participants were “out of window”. Symptoms of urinary tract and bladder infections were observed to be primary reasons for missed sessions for participants with SCI. For stroke, pain from falls at home and unexpected sciatica were the leading causes of missed sessions. Two participants (SCI=1, stroke=1) missed sessions due to Covid-19 (SCI, 22 weeks completion rate; stroke, 16 weeks).

Conclusions: Despite interruptions among the two diagnoses groups, the majority of participants (~70%) completed the intervention sessions within window. Future studies should consider the unique characteristics of SCI and stroke populations when developing expectations for compliance with intervention timelines.

Author(s) Disclosures: DARPA (N66001-17-2-4011) and NINDS (UH3NS109497) funding received for these studies.