Relationship between reticulospinal system sensitization and proprioceptive pathways in the development of dynamic spasticity (ReProDS) post-spinal cord injury: protocol for a prospective, observational cohort study.

Background: Dynamic spasticity (DS) is a common complication post-spinal cord injury (SCI), marked by intermittent increases in muscle tone during postural transitions or movement. Despite its prevalence, high-quality research on DS incidence, risk factors, and underlying mechanisms in SCI patients remains limited. With the growing application of spinal cord stimulation (SCS) for spasticity control, the role of proprioception in DS development has garnered attention. Additionally, advances in diffusion tensor imaging (DTI) allow for the analysis of the reticulospinal tract's (RST) role in postural control among SCI patients. However, the impact of microstructural changes in RST and proprioception on DS following SCI remains unclear.

Objective: To investigate the relationship between microstructural changes in the RST and proprioceptive circuits in SCI patients, exploring their association with DS and potential predictive factors that influence recovery.

Methods: This is a 12-month prospective cohort study. The neurophysiological and global functional status of the participants will be assessed. Primary outcomes include DTI indices of RST and proprioception, and spasticity assessment. Secondary outcomes include auditory startle reflex (ASR), H-reflex, shear wave velocity (SWV), overall functional status including spinal cord independence measure, gait analysis, modified Barthel Index, and the 36-item short form health survey. Data will be collected at 1, 3, 6, and 12 months after enrolment. Matched healthy controls will be measured during the same period after recruitment.

Discussion: This study is the first to explore the role of microstructural changes in the RST and proprioception in the assessment and prediction of DS following SCI. The findings aim to enhance theoretical understanding of SCS in spasticity management and to establish pre-treatment criteria for SCS interventions targeting motor function recovery in SCI.

Trial registration number: ChiCTR2400090724.