Effects of Remote Ischemic Conditioning on Hand Engagement in individuals with Spinal cord Injury (RICHES): A Preliminary Crossover Study
Abstract BackgroundMost spinal cord injuries (SCI) are not full transections, indicating that residual nerve circuits are retained after injury. SCI rehabilitation interventions, including physical training and neural stimulation, have been shown to beneficially reorganize motor pathways in the brain, corticospinal tract (CST), and at the spinal level. However, both physical training and neural stimulation require a large number of repetitions, and the retention of the intervention effects may be transient. Therefore, the need remains for an effective approach to synergistically improve the amount and duration of neuroplasticity in combination with other interventions. Remote ischemic conditioning (RIC) demonstrates several potential advantages as a candidate for such an approach. In this proposed study, we will investigate RIC coupled with physical training to promote neuroplasticity in hand muscles after cervical SCI This will be the first study to introduce RIC in the SCI population, so we will extensively focus on safety, tolerability, and hemodynamic responses during RIC.MethodsThis is a prospective randomized-order crossover trial to be performed over 24 months in 16 participants including 8 healthy controls and 8 participants with chronic cervical SCI. Patients will participate in one screening session (SCI subjects only) and two experimental sessions consisting of either active or sham RIC preceding a bout of pinch movement exercise. Serial evaluations will be carried out at baseline, after RIC, immediately after pinch exercise, and follow up 15-minutes later. The primary outcome is the change in corticospinal excitability (primarily measured by the motor evoked potential of abductor pollicis brevis muscle). Secondary outcomes will include maximal volitional pinch force, and inflammatory biomarkers such as components of the TLR signaling pathway. To ensure safety, we will monitor tolerability and hemodynamic responses during RIC.DiscussionThis study is the first to test RIC in people with cervical spinal cord injury and to investigate whether RIC alters corticospinal excitability. By sharing the details of our research protocol, we hope other interested researchers will seek to investigate similar approaches – depending on overlap with the current study and mutual sharing of participant-level data, this could increase the sample size, power, and generalizability of the analysis and results.