Spinal cord transcutaneous stimulation (scTS) offers a promising approach to enhance cardiovascular regulation in individuals with a high-level spinal cord injury (SCI), addressing the challenges of unstable blood pressure (BP) and the accompanying hypo- and hypertensive events. While scTS offers flexibility in stimulation locations, it also leads to significant variability and lack of validation in stimulation sites utilized by studies. Our study presents findings from a case series involving eight individuals with chronic cervical SCI, examining the hemodynamic effects of scTS applied in different vertebral locations, spanning from high cervical to sacral regions. Stimulation of the lumbosacral vertebrae region (L1/2, S1/2, and also including T11/12) significantly elevated BP, unlike cervical or upper thoracic stimulation. The observed trend, which remained consistent across different participants, highlights the promising role of lumbosacral stimulation in neuromodulating BP.

Central cord syndrome (CCS) is the most common, yet most controversial, among the different spinal cord injury (SCI) incomplete syndromes. Since its original description in 1954, many variations have been described while maintaining the core characteristic of disproportionate weakness in the upper extremities compared to the lower extremities. Several definitions have been proposed in an attempt to quantify this difference, including a widely accepted criterion of ≥10 motor points in favor of the lower extremities. Nevertheless, recent reports have recommended revisiting the terminology and criteria of CCS as existing definitions do not capture the entire essence of the syndrome. Due to methodological differences, the full extent of CCS is not known, and a large variation in prevalence has been described. This review classifies the different definitions of CCS and describes some inherent limitations, highlighting the need for universal quantifiable criteria.

Central cord syndrome (CCS) is the most prevalent and debated incomplete spinal cord injury (SCI) syndrome, with its hallmark feature being more pronounced weakness of the upper extremities than of the lower extremities. Varying definitions encapsulate multiple clinical features under the single umbrella term of CCS, complicating evaluation of its frequency, prognosis discussions, and outcomes research. Often, people with CCS are excluded from research protocols, as it is thought to have a favorable prognosis, but the vague nature of CCS raises doubts about the validity of this practice. The objective of this study was to categorize CCS into specific subsets with clear quantifiable differences, to assess whether this would enhance the ability to determine if individuals with CCS or its subsets exhibit distinct neurological and functional outcomes relative to others with incomplete tetraplegia. This study retrospectively reviewed individuals with new motor incomplete tetraplegia from traumatic SCI who enrolled in the Spinal Cord Injury Model Systems (SCIMS) database from 2010 to 2020. Through an assessment of the prevailing criteria for CCS, coupled with data analysis, we used two key criteria, including the severity of distal upper extremity weakness (i.e., hands and fingers) and extent of symmetry, to delineate three CCS subsets: full CCS, unilateral CCS, and borderline CCS. Of the 1490 participants in our sample, 17.5% had full, 25.6% had unilateral, and 9% had borderline CCS, together encompassing >50% of motor incomplete tetraplegia cases. Despite the increased sensitivity and specificity of these subsets compared with existing quantifiable criteria, substantial variability in clinical presentation was still observed. Overall, individuals meeting CCS subset criteria showed a higher likelihood of American Spinal Injury Association (ASIA) Impairment Scale (AIS) D grade than those with motor incomplete tetraplegia without CCS. Upper Extremity Motor Score (UEMS) for those with CCS was lower on admission, a difference that diminished by discharge, whereas their Lower Extremity Motor Score (LEMS) consistently remained higher than for those without CCS. However, these neurological distinctions did not result in significant functional differences, as lower and upper extremity functional outcomes at discharge were mostly similar, with some differences observed within those with AIS D grade. The AIS grade, rather than the diagnosis of CCS, remains the foremost determinant influencing neurological and functional outcomes. We recommend that future studies consider incorporating motor incomplete tetraplegia into their inclusion/exclusion criteria, instead of relying on criteria specific to CCS. Although there remains clinical value in characterizing an injury pattern as CCS and perhaps using the different subsets to better characterize the impairments, it does not appear to be a useful research criterion.

The expanding application of spinal stimulation therapies in spinal cord injury (SCI) rehabilitation necessitates a critical reexamination of cardiovascular (CV) responses to these interventions. A key question arises: How should blood pressure (BP) responses to stimulation be interpreted, and does the conventional definition of autonomic dysreflexia (AD) adequately capture these phenomena? Researchers remain divided—some classify BP elevations during stimulation as AD, while others attribute them to intentional neuromodulation targeting sympathetic preganglionic neurons. This review scrutinizes the various AD definitions in the literature, including the conventional threshold (systolic BP increase >20 mmHg), revealing substantial limitations in research contexts. While symptomatic AD occurs in only 4-7% of stimulation study participants, asymptomatic BP increases are considerably more frequent. This established threshold lacks robust physiological rationale and creates significant interpretive challenges, particularly when evaluating interventions designed to modulate BP responses. The current limitations of guideline-based definitions of AD challenge research interpretation and clinical translation. Although several publications describe AD as “unregulated” or “uncontrolled,” it has not yet been incorporated into formal guideline definitions. This review underscores the need for a collaborative effort to refine AD definitions in research, particularly in the context of spinal stimulation. Future consensus development should address whether uniform thresholds should apply across different contexts, how to integrate heart rate dynamics and absolute BP values alongside symptomatic status, and how to meaningfully distinguish therapeutic BP modulation from adverse autonomic responses. This is essential for standardizing research approaches, optimizing stimulation parameters, and ensuring efficacy and safety as spinal stimulation technologies advance clinically.

Background/Objectives: Cardiovascular (CV) dysfunction and, specifically, orthostatic hypotension, may significantly impact the quality of life of individuals with spinal cord injuries (SCIs) at T6 or above. While spinal cord transcutaneous stimulation (scTS) has shown immediate effects on blood pressure regulation, its long-term effects remain largely unexplored. Methods: This case study examines the sustained effects of scTS on blood pressure regulation and orthostatic tolerance in a 33-year-old female with cervical (C4) complete SCI sustained two years earlier. This individual underwent an initial baseline tilt test without stimulation, completed six 30 min scTS-CV sessions (cardiovascular-focused stimulation) over two weeks as the “training” phase, and then had repeated tilt tests without stimulation posttraining. Results: Following training, the participant demonstrated an improvement in orthostatic tolerance, maintaining a 70° tilt for 30 min, compared to only 3 min at baseline, in a tilt test (without stimulation) conducted one day posttraining. Self-reported reduction in orthostatic burden and decreased midodrine dependence were also observed for several weeks, with improvements diminishing by 6 weeks posttraining. Conclusions: These observations suggest that brief, repeated scTS-CV sessions may lead to sustained improvements in orthostatic tolerance beyond the immediate period of stimulation. Although the duration of these effects has yet to be established, this approach could offer a non-invasive alternative for managing CV dysfunction in SCIs.