The revised zone of partial preservation (ZPP) in the 2019 International Standards for Neurological Classification of Spinal Cord Injury: ZPP applicability in incomplete injuries.

STUDY DESIGN: Consensus process. OBJECTIVES: To provide a reference for the Zone(s) of Partial Preservation (ZPP) in the 2019 International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) and analyze the initial impact of applicability of the revised ZPPs. Revisions include the use of ZPPs in selected incomplete injuries (in addition to prior use in sensorimotor complete injuries). Specifically, the revised motor ZPPs are applicable bilaterally in injuries with absent voluntary anal contraction (VAC) and the revised sensory ZPP for a given side is applicable if deep anal pressure (DAP), light touch and pin prick sensation in S4-5 are absent on that side. SETTING: Committee with 16 ISNCSCI experts and datasets from the European Multicenter Study about Spinal Cord Injury (EMSCI). METHODS: Occurrence frequencies of applicable ZPPs were determined in an EMSCI cohort consisting of two ISNCSCI examinations from 665 individuals with traumatic SCI. RESULTS: Motor ZPPs were derived in 35.2% of all datasets of incomplete injuries, while sensory ZPPs are much less frequent (1.0%). Motor ZPPs are applicable in all American Spinal Injury Association Impairment Scale (AIS) B datasets (mean ZPP length: 0.9 ± 1.0 segments), in 55.4% of all AIS C datasets (ZPP length: 11.8 ± 8.2 segments) and in 9.9% of the AIS D datasets (ZPP length: 15.4 ± 7.9 segments). CONCLUSIONS: The revised ZPP allows for determining motor ZPPs in approximately 1/3 of all incomplete injuries. The broadened applicability enables the use of ZPPs beyond complete injuries for complementary description of residual functions in more individuals. SPONSORSHIP: N/A.

Neuromodulation with transcutaneous spinal stimulation reveals different groups of motor profiles during robot-guided stepping in humans with incomplete spinal cord injury.

Neuromodulation via spinal stimulation has been investigated for improving motor function and reducing spasticity after spinal cord injury (SCI) in humans. Despite the reported heterogeneity of outcomes, few investigations have attempted to discern commonalities among individual responses to neuromodulation, especially the impact of stimulation frequencies. Here, we examined how exposure to continuous lumbosacral transcutaneous spinal stimulation (TSS) across a range of frequencies affects robotic torques and EMG patterns during stepping in a robotic gait orthosis on a motorized treadmill. We studied nine chronic motor-incomplete SCI individuals (8/1 AIS-C/D, 8 men) during robot-guided stepping with body-weight support without and with TSS applied at random frequencies between 1 and up to 100 Hz at a constant, individually selected stimulation intensity below the common motor threshold for posterior root reflexes. The hip and knee robotic torques needed to maintain the predefined stepping trajectory and EMG in eight bilateral leg muscles were recorded. We calculated the standardized mean difference between the stimulation conditions grouped into frequency bins and the no stimulation condition to determine changes in the normalized torques and the average EMG envelopes. We found heterogeneous changes in robotic torques across individuals. Agglomerative clustering of robotic torques identified four groups wherein the patterns of changes differed in magnitude and direction depending mainly on the stimulation frequency and stance/swing phase. On one end of the spectrum, the changes in robotic torques were greater with increasing stimulation frequencies (four participants), which coincided with a decrease in EMG, mainly due to the reduction of clonogenic motor output in the lower leg muscles. On the other end, we found an inverted u-shape change in torque over the mid-frequency range along with an increase in EMG, reflecting the augmentation of gait-related physiological (two participants) or pathophysiological (one participant) output. We conclude that TSS during robot-guided stepping reveals different frequency-dependent motor profiles among individuals with chronic motor incomplete SCI. This suggests the need for a better understanding and characterization of motor control profiles in SCI when applying TSS as a therapeutic intervention for improving gait.

Temporal and spatial dynamics of spinal sensorimotor processing in an intersegmental cutaneous nociceptive reflex.

The cutaneus trunci muscle (CTM) reflex produces a skin "shrug" in response to pinch on a rat's back through a three-part neural circuit: 1) A-fiber and C-fiber afferents in segmental dorsal cutaneous nerves (DCNs) from lumbar to cervical levels, 2) ascending propriospinal interneurons, and 3) the CTM motoneuron pool located at the cervicothoracic junction. We recorded neurograms from a CTM nerve branch in response to electrical stimulation. The pulse trains were delivered at multiple DCNs (T6-L1), on both sides of the midline, at two stimulus strengths (0.5 or 5 mA, to activate Aδ fibers or Aδ and C fibers, respectively) and four stimulation frequencies (1, 2, 5, or 10 Hz) for 20 s. We quantified both the temporal dynamics (i.e., latency, sensitization, habituation, and frequency dependence) and the spatial dynamics (spinal level) of the reflex. The evoked responses were time-windowed into Early, Mid, Late, and Ongoing phases, of which the Mid phase, between the Early (Aδ fiber mediated) and Late (C fiber mediated) phases, has not been previously identified. All phases of the response varied with stimulus strength, frequency, history, and DCN level/side stimulated. In addition, we observed nociceptive characteristics like C fiber-mediated sensitization (wind-up) and habituation. Finally, the range of latencies in the ipsilateral responses were not very large rostrocaudally, suggesting a myelinated neural path within the ipsilateral spinal cord for at least the A fiber-mediated Early-phase response. Overall, these results demonstrate that the CTM reflex shares the temporal dynamics in other nociceptive reflexes and exhibits spatial (segmental and lateral) dynamics not seen in those reflexes.NEW & NOTEWORTHY We have physiologically studied an intersegmental reflex exploring detailed temporal, stimulus strength-based, stimulation history-dependent, lateral and segmental quantification of the reflex responses to cutaneous nociceptive stimulations. We found several physiological features in this reflex pathway, e.g., wind-up, latency changes, and somatotopic differences. These physiological observations allow us to understand how the anatomy of this reflex may be organized. We have also identified a new phase of this reflex, termed the "mid" response.

Application of electrophysiological measures in spinal cord injury clinical trials: a narrative review.

STUDY DESIGN: Narrative review. OBJECTIVES: To discuss how electrophysiology may contribute to future clinical trials in spinal cord injury (SCI) in terms of: (1) improvement of SCI diagnosis, patient stratification and determination of exclusion criteria; (2) the assessment of adverse events; and (3) detection of therapeutic effects following an intervention. METHODS: An international expert panel for electrophysiological measures in SCI searched and discussed the literature focused on the topic. RESULTS: Electrophysiology represents a valid method to detect, track, and quantify readouts of nerve functions including signal conduction, e.g., evoked potentials testing long spinal tracts, and neural processing, e.g., reflex testing. Furthermore, electrophysiological measures can predict functional outcomes and thereby guide rehabilitation programs and therapeutic interventions for clinical studies. CONCLUSION: Objective and quantitative measures of sensory, motor, and autonomic function based on electrophysiological techniques are promising tools to inform and improve future SCI trials. Complementing clinical outcome measures, electrophysiological recordings can improve the SCI diagnosis and patient stratification, as well as the detection of both beneficial and adverse events. Specifically composed electrophysiological measures can be used to characterize the topography and completeness of SCI and reveal neuronal integrity below the lesion, a prerequisite for the success of any interventional trial. Further validation of electrophysiological tools with regard to their validity, reliability, and sensitivity are needed in order to become routinely applied in clinical SCI trials.

Comparison of peak oxygen consumption response to aquatic and robotic therapy in individuals with chronic motor incomplete spinal cord injury: a randomized controlled trial.

STUDY DESIGN: Randomized dual center controlled clinical trial. OBJECTIVE: To determine and compare the cardiorespiratory impact of 3 months of aquatic and robotic therapy for individuals with chronic motor incomplete spinal cord injury (CMISCI). SETTINGS: Two rehabilitation specialty hospitals. METHODS: Thirty-one individuals with CMISCI with neurological level between C2-T12 at least 1 year post injury were randomized to either aquatic or robotic treadmill therapy for 36 sessions. Customized sessions lasted 40-45 min at 65-75% heart rate reserve intensity with peak oxygen consumption (peak VO2) measured during arm ergometry at baseline and post intervention. Additional peak robotic treadmill VO2 assessments were obtained before and after training for participants randomized to robotic intervention. RESULTS: Peak VO2 measured with arm ergometry was not significantly different with either aquatic intervention (8.1%, p = 0.14, n = 15) or robotic intervention (-0.7%, p = 0.31, n = 17). Peak VO2 measured with robotic treadmill ergometry demonstrated a statistical improvement (14.7%, p = 0.03, n = 17, two-tailed t-test) across the robotic intervention. Comparison between the two interventions demonstrated a trend favoring aquatic therapy for improving arm ergometry peak VO2 (ANOVA, p = 0.063). CONCLUSIONS: Neither 3-month exercise interventions statistically improved arm cycle ergometry peak VO2, our cardiorespiratory surrogate marker, although percent improvement was greater in the aquatic exercise condition. Robotic ergometry peak VO2 did improve for the robotic intervention, confirming previous work. These results suggest that either intervention may hold utility in improving cardiorespiratory fitness in CMISCI, but peak VO2 measurement technique appears critical in detecting effects. SPONSORSHIP: DOD CDMRP SCI Research Program Clinical Trial Award SC090147, FY 2009. This study is registered under ClinicalTrials.gov Identifier: NCT01407354.

Central Plasticity of Cutaneous Afferents Is Associated with Nociceptive Hyperreflexia after Spinal Cord Injury in Rats.

Electrical stimulations of dorsal cutaneous nerves (DCNs) at each lumbothoracic spinal level produce the bilateral cutaneus trunci muscle (CTM) reflex responses which consist of two temporal components: an early and late responses purportedly mediated by Aδ and C fibers, respectively. We have previously reported central projections of DCN A and C fibers and demonstrated that different projection patterns of those afferent types contributed to the somatotopic organization of CTM reflex responses. Unilateral hemisection spinal cord injury (SCI) was made at T10 spinal segments to investigate the plasticity of early and late CTM responses 6 weeks after injury. Both early and late responses were drastically increased in response to both ipsi- and contralateral DCN stimulations both above (T6 and T8) and below (T12 and L1) the levels of injury demonstrating that nociceptive hyperreflexia developed at 6 weeks following hemisection SCI. We also found that DCN A and C fibers centrally sprouted, expanded their projection areas, and increased synaptic terminations in both T7 and T13, which correlated with the size of hemisection injury. These data demonstrate that central sprouting of cutaneous afferents away from the site of injury is closely associated with enhanced responses of intraspinal signal processing potentially contributing to nociceptive hyperreflexia following SCI.

Lower extremity outcome measures: considerations for clinical trials in spinal cord injury.

STUDY DESIGN: This is a focused review article. OBJECTIVES: To identify important concepts in lower extremity (LE) assessment with a focus on locomotor outcomes and provide guidance on how existing outcome measurement tools may be best used to assess experimental therapies in spinal cord injury (SCI). The emphasis lies on LE outcomes in individuals with complete and incomplete SCI in Phase II-III trials. METHODS: This review includes a summary of topics discussed during a workshop focusing on LE function in SCI, conceptual discussion of corresponding outcome measures and additional focused literature review. RESULTS: There are a number of sensitive, accurate, and responsive outcome tools measuring both quantitative and qualitative aspects of LE function. However, in trials with individuals with very acute injuries, a baseline assessment of the primary (or secondary) LE outcome measure is often not feasible. CONCLUSION: There is no single outcome measure to assess all individuals with SCI that can be used to monitor changes in LE function regardless of severity and level of injury. Surrogate markers have to be used to assess LE function in individuals with severe SCI. However, it is generally agreed that a direct measurement of the performance for an appropriate functional activity supersedes any surrogate marker. LE assessments have to be refined so they can be used across all time points after SCI, regardless of the level or severity of spinal injury. SPONSORS: Craig H. Neilsen Foundation, Spinal Cord Outcomes Partnership Endeavor.

Considerations and recommendations for selection and utilization of upper extremity clinical outcome assessments in human spinal cord injury trials.

STUDY DESIGN: This is a focused review article. OBJECTIVES: This review presents important features of clinical outcomes assessments (COAs) in human spinal cord injury research. Considerations for COAs by trial phase and International Classification of Functioning, Disability and Health are presented as well as strengths and recommendations for upper extremity COAs for research. Clinical trial tools and designs to address recruitment challenges are identified. METHODS: The methods include a summary of topics discussed during a two-day workshop, conceptual discussion of upper extremity COAs and additional focused literature review. RESULTS: COAs must be appropriate to trial phase and particularly in mid-late-phase trials, should reflect recovery vs. compensation, as well as being clinically meaningful. The impact and extent of upper vs. lower motoneuron disease should be considered, as this may affect how an individual may respond to a given therapeutic. For trials with broad inclusion criteria, the content of COAs should cover all severities and levels of SCI. Specific measures to assess upper extremity function as well as more comprehensive COAs are under development. In addition to appropriate use of COAs, methods to increase recruitment, such as adaptive trial designs and prognostic modeling to prospectively stratify heterogeneous populations into appropriate cohorts should be considered. CONCLUSIONS: With an increasing number of clinical trials focusing on improving upper extremity function, it is essential to consider a range of factors when choosing a COA. SPONSORS: Craig H. Neilsen Foundation, Spinal Cord Outcomes Partnership Endeavor.

Rehabilitation Research at the National Institutes of Health: Moving the Field Forward (Executive Summary).

Approximately 53 million Americans live with a disability. For decades, the National Institutes of Health (NIH) has been conducting and supporting research to discover new ways to minimize disability and enhance the quality of life of people with disabilities. After the passage of the Americans With Disabilities Act, NIH established the National Center for Medical Rehabilitation Research, with the goal of developing and implementing a rehabilitation research agenda. Currently, 17 institutes and centers at NIH invest more than $500 million per year in rehabilitation research. Recently, the director of NIH, Francis Collins, appointed a Blue Ribbon Panel to evaluate the status of rehabilitation research across institutes and centers. As a follow-up to the work of that panel, NIH recently organized a conference, "Rehabilitation Research at NIH: Moving the Field Forward." This report is a summary of the discussions and proposals that will help guide rehabilitation research at NIH in the near future.

Reliability and Validity of S3 Pressure Sensation as an Alternative to Deep Anal Pressure in Neurologic Classification of Persons With Spinal Cord Injury.

OBJECTIVE: To determine whether pressure sensation at the S3 dermatome (a new test) could be used in place of deep anal pressure (DAP) to determine completeness of injury as part of the International Standards for Neurological Classification of Spinal Cord Injury. DESIGN: Prospective, multicenter observational study. SETTING: U.S. Spinal Cord Injury Model Systems. PARTICIPANTS: Persons (N=125) with acute traumatic spinal cord injury (SCI), neurologic levels T12 and above, were serially examined at 1 month (baseline), 3, 6, and 12 months postinjury. There were 80 subjects with tetraplegia and 45 with paraplegia. INTERVENTIONS: S3 pressure sensation at all time points, with a retest at the 1-month time point. MAIN OUTCOME MEASURES: Test-retest reliability and agreement (κ), sensitivity, specificity, positive and negative predictive values. RESULTS: Test-retest reliability of S3 pressure at 1 month was almost perfect (κ=.98). Agreement of S3 pressure with DAP was substantial both at 1 month (κ=.73) and for all time points combined (κ=.76). The positive predictive value of S3 pressure for DAP was 89.3% at baseline and 90.3% for all time points. No pattern in outcomes was seen in those cases where S3 pressure and DAP differed at 1 month. CONCLUSIONS: S3 pressure sensation is reliable and has substantial agreement with DAP in persons with SCI at least 1 month postinjury. We suggest S3 pressure as an alternative test of sensory sacral sparing for supraconus SCI, at least in cases where DAP cannot be tested. Further research is needed to determine whether S3 pressure could replace DAP for classification of SCI.

Spinal cord injury medicine and rehabilitation.

The rehabilitation of spinal cord injury (SCI) is a complicated process, but one in which new research is developing novel and increasingly promising methods of restorative neurology. Spinal cord injury medicine addresses not only the neurologic injury, but all the secondary complications in other organ systems whose regulation is disrupted after SCI. To some degree, the rehabilitation of SCI is focused on return to the community and functional goals are paramount, regardless of whether they can be achieved through some mechanism of compensation or due to a growing effort at engendering neurologic plasticity and recovery. The authors present a typical case of cervical incomplete SCI and discuss the medical complications and considerations for care during acute rehabilitation. They also review current methods of planning and executing rehabilitation, along with emerging methods that are leading to, in varying degrees, greater neurologic recovery. Finally, new approaches in SCI rehabilitation, namely neuromodulation, are discussed as efforts are made to further augment neural plasticity and recovery in SCI.

Activity-based therapy for recovery of walking in individuals with chronic spinal cord injury: results from a randomized clinical trial.

OBJECTIVE: To examine the effects of activity-based therapy (ABT) on neurologic function, walking ability, functional independence, metabolic health, and community participation. DESIGN: Randomized controlled trial with delayed treatment design. SETTING: Outpatient program in a private, nonprofit rehabilitation hospital. PARTICIPANTS: Volunteer sample of adults (N=48; 37 men and 11 women; age, 18-66y) with chronic (≥12mo postinjury), motor-incomplete (ASIA Impairment Scale grade C or D) spinal cord injury (SCI). INTERVENTIONS: A total of 9h/wk of ABT for 24 weeks including developmental sequencing; resistance training; repetitive, patterned motor activity; and task-specific locomotor training. Algorithms were used to guide group allocation, functional electrical stimulation utilization, and locomotor training progression. MAIN OUTCOME MEASURES: Neurologic function (International Standards for Neurological Classification of Spinal Cord Injury); walking speed and endurance (10-meter walk test, 6-minute walk test, and Timed Up and Go test); community participation (Spinal Cord Independence Measure, version III, and Reintegration to Normal Living Index); and metabolic function (weight, body mass index, and Quantitative Insulin Sensitivity Check). RESULTS: Significant improvements in neurologic function were noted for experimental versus control groups (International Standards for Neurological Classification of Spinal Cord Injury total motor score [5.1±6.3 vs 0.9±5.0; P=.024] and lower extremity motor score [4.2±5.2 vs -0.6±4.2; P=.004]). Significant differences between experimental and control groups were observed for 10-meter walk test speed (0.096±0.14m/s vs 0.027±0.10m/s; P=.036) and 6-minute walk test total distance (35.97±48.2m vs 3.0±25.5m; P=.002). CONCLUSIONS: ABT has the potential to promote neurologic recovery and enhance walking ability in individuals with chronic, motor-incomplete SCI. However, further analysis is needed to determine for whom ABT is going to lead to meaningful clinical benefits.

Activity-based therapy for recovery of walking in chronic spinal cord injury: results from a secondary analysis to determine responsiveness to therapy.

OBJECTIVE: To gain insight into who is likely to benefit from activity-based therapy (ABT), as assessed by secondary analysis of data obtained from a clinical trial. DESIGN: Secondary analysis of results from a randomized controlled trial with delayed treatment design. SETTING: Outpatient program in a private, nonprofit rehabilitation hospital. PARTICIPANTS: Volunteer sample of adults (N=38; 27 men; 11 women; age, 22-63y) with chronic (≥12mo postinjury), motor-incomplete (American Spinal Injury Association [ASIA] Impairment Scale [AIS] grade C or D) spinal cord injury (SCI). INTERVENTIONS: A total of 9h/wk of ABT for 24 weeks including developmental sequencing; resistance training; repetitive, patterned motor activity; and task-specific locomotor training. Algorithms were used to guide group allocation, functional electrical stimulation utilization, and locomotor training progression. MAIN OUTCOME MEASURES: Walking speed and endurance (10-meter walk test and 6-minute walk test) and functional ambulation (timed Up and Go test). RESULTS: This secondary analysis identified likely responders to ABT on the basis of injury characteristics: AIS classification, time since injury, and initial walking ability. Training effects were the most clinically significant in AIS grade D participants with injuries <3 years in duration. This information, along with information about preliminary responsiveness to therapy (gains after 12wk), can help predict the degree of recovery likely from participation in an ABT program. CONCLUSIONS: ABT has the potential to promote neurologic recovery and enhance walking ability in individuals with chronic, motor-incomplete SCI. However, not everyone with goals of walking recovery will benefit. Individuals with SCI should be advised of the time, effort, and resources required to undertake ABT. Practitioners are encouraged to use the findings from this trial to assist prospective participants in establishing realistic expectations for recovery.

Modification of spasticity by transcutaneous spinal cord stimulation in individuals with incomplete spinal cord injury.

CONTEXT/OBJECTIVE: To examine the effects of transcutaneous spinal cord stimulation (tSCS) on lower-limb spasticity. DESIGN: Interventional pilot study to produce preliminary data. SETTING: Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria. PARTICIPANTS: Three subjects with chronic motor-incomplete spinal cord injury (SCI) who could walk ≥10 m. INTERVENTIONS: Two interconnected stimulating skin electrodes (Ø 5 cm) were placed paraspinally at the T11/T12 vertebral levels, and two rectangular electrodes (8 × 13 cm) on the abdomen for the reference. Biphasic 2 ms-width pulses were delivered at 50 Hz for 30 minutes at intensities producing paraesthesias but no motor responses in the lower limbs. OUTCOME MEASURES: The Wartenberg pendulum test and neurological recordings of surface-electromyography (EMG) were used to assess effects on exaggerated reflex excitability. Non-functional co-activation during volitional movement was evaluated. The timed 10-m walk test provided measures of clinical function. RESULTS: The index of spasticity derived from the pendulum test changed from 0.8 ± 0.4 pre- to 0.9 ± 0.3 post-stimulation, with an improvement in the subject with the lowest pre-stimulation index. Exaggerated reflex responsiveness was decreased after tSCS across all subjects, with the most profound effect on passive lower-limb movement (pre- to post-tSCS EMG ratio: 0.2 ± 0.1), as was non-functional co-activation during voluntary movement. Gait speed values increased in two subjects by 39%. CONCLUSION: These preliminary results suggest that tSCS, similar to epidurally delivered stimulation, may be used for spasticity control, without negatively impacting residual motor control in incomplete SCI. Further study in a larger population is warranted.

Relationship between ASIA examination and functional outcomes in the NeuroRecovery Network Locomotor Training Program.

OBJECTIVE: To determine the effects of locomotor training on: (1) the International Standards for Neurological Classification of Spinal Cord Injury examination; (2) locomotion (gait speed, distance); (3) balance; and (4) functional gait speed stratifications after chronic incomplete spinal cord injury (SCI). DESIGN: Prospective observational cohort. SETTING: Outpatient rehabilitation centers in the NeuroRecovery Network (NRN). PARTICIPANTS: Individuals (n=225) with American Spinal Injury Association Impairment Scale (AIS) grade C or D chronic motor incomplete SCI having completed locomotor training in the NRN. INTERVENTION: The NRN Locomotor Training Program consists of manual-facilitated body weight-supported standing and stepping on a treadmill and overground. MAIN OUTCOME MEASURES: AIS classification, lower extremity pin prick, light touch and motor scores, ten-meter walk and six-minute walk tests, and the Berg Balance Scale. RESULTS: Significant gains occurred in lower extremity motor scores but not in sensory scores, and these were only weakly related to gait speed and distance. Final Berg Balance Scale scores and initial lower extremity motor scores were positively related. Although 70% of subjects showed significantly improved gait speed after locomotor training, only 8% showed AIS category conversion. CONCLUSIONS: Locomotor training improves gait speed to levels sufficient for independent in-home or community ambulation after chronic motor incomplete SCI. Changes in lower extremity motor and sensory scores do not capture the full extent of functional recovery, nor predict responsiveness to locomotor training. Functional classification based on gait speed may provide an effective measure of treatment efficacy or functional improvement after incomplete SCI.

Profiling motor control in spinal cord injury: moving towards individualized therapy and evidence-based care progression.

This article, based on the keynote address at the 5th National Spinal Cord Injury Conference in Toronto, addresses methods to neurophysiologically characterize patients after spinal cord injury and proposes how those methods could be used to individualize therapeutic interventions and monitor their efficacy over the course of neurorehabilitation.

Soleus H and Lower Limb Posterior Root Muscle Reflexes During Stepping After Incomplete SCI.

The goal of this study was to examine and compare the step cycle related modulation of the soleus H and posterior root muscle (PRM) reflexes in subjects with and without spinal cord injury. Ten subjects without neurological injury and fifteen subjects with spinal cord injury (SCI) underwent soleus H reflex and lower limb PRM reflex testing while standing and stepping in a robotic gait orthosis. Reflex amplitudes were evaluated during standing, mid stance and mid swing to determine if speed and/or injury altered step cycle related neuromodulation. H and PRM reflexes in the soleus underwent step cycle related modulation in injured and uninjured subjects though the degree of modulation differed between the two reflexes with the H reflex showing more step cycle related modulation. We found in the SCI group that both the soleus H and soleus PRM reflex amplitudes were higher relative to the non-injured group and modulated less during the step cycle. We also found that modulation of the soleus H reflex, but not soleus PRM reflex, correlated to the lower extremity motor scores in individuals with SCI. Our evidence suggests that the inability to provide appropriate step cycle related reflex modulation may be due to decreased supra-spinal regulation of motoneuron and spinal excitability and could be an indicator of the severity of injury as it relates to clinically measured lower extremity motor scores.