Influence of a locomotor training approach on walking speed and distance in people with chronic spinal cord injury: a randomized clinical trial

A clinically meaningful training effect in walking speed using functional electrical stimulation for motor-incomplete spinal cord injury

CONTEXT/OBJECTIVE

The study aimed to investigate the presence of a training effect for rehabilitation of walking function in motor-incomplete spinal cord injury (SCI) through daily use of functional electrical stimulation (FES).

SETTING

A specialist FES outpatient centre.

PARTICIPANTS

Thirty-five participants (mean age 53, SD 15, range 18-80; mean years since diagnosis 9, range 5 months - 39 years) with drop foot and motor-incomplete SCI (T12 or higher, ASIA Impairment Scale C and D) able to ambulate 10 metres with the use of a walking stick or frame.

INTERVENTIONS

FES of the peroneal nerve, glutei and hamstrings as clinically indicated over six months in the community.

OUTCOME MEASURES

The data was analysed for a training effect (difference between unassisted ten metre walking speed at baseline and after six months) and orthotic effects (difference between walking speed with and without FES) initially on day one and after six months. The data was further analysed for a minimum clinically important difference (MCID) (>0.06 m/s).

RESULTS

A clinically meaningful, significant change was observed for initial orthotic effect (0.13m/s, CI: 0.04-0.17, P = 0.013), total orthotic effect (0.11m/s, CI: 0.04-0.18, P = 0.017) and training effect (0.09m/s, CI: 0.02-0.16, P = 0.025).

CONCLUSION

The results suggest that daily independent use of FES may produce clinically meaningful changes in walking speed which are significant for motor-incomplete SCI. Further research exploring the mechanism for the presence of a training effect may be beneficial in targeting therapies for future rehabilitation.

A multidirectional gravity-assist algorithm that enhances locomotor control in patients with stroke or spinal cord injury

Gait recovery after neurological disorders requires remastering the interplay between body mechanics and gravitational forces. Despite the importance of gravity-dependent gait interactions and active participation for promoting this learning, these essential components of gait rehabilitation have received comparatively little attention. To address these issues, we developed an adaptive algorithm that personalizes multidirectional forces applied to the trunk based on patient-specific motor deficits. Implementation of this algorithm in a robotic interface reestablished gait dynamics during highly participative locomotion within a large and safe environment. This multidirectional gravity-assist enabled natural walking in nonambulatory individuals with spinal cord injury or stroke and enhanced skilled locomotor control in the less-impaired subjects. A 1-hour training session with multidirectional gravity-assist improved locomotor performance tested without robotic assistance immediately after training, whereas walking the same distance on a treadmill did not ameliorate gait. These results highlight the importance of precise trunk support to deliver gait rehabilitation protocols and establish a practical framework to apply these concepts in clinical routine.

Advanced Robotic Therapy Integrated Centers (ARTIC): an international collaboration facilitating the application of rehabilitation technologies

Background

The application of rehabilitation robots has grown during the last decade. While meta-analyses have shown beneficial effects of robotic interventions for some patient groups, the evidence is less in others. We established the Advanced Robotic Therapy Integrated Centers (ARTIC) network with the goal of advancing the science and clinical practice of rehabilitation robotics. The investigators hope to exploit variations in practice to learn about current clinical application and outcomes. The aim of this paper is to introduce the ARTIC network to the clinical and research community, present the initial data set and its characteristics and compare the outcome data collected so far with data from prior studies.

Methods

ARTIC is a pragmatic observational study of clinical care. The database includes patients with various neurological and gait deficits who used the driven gait orthosis Lokomat® as part of their treatment. Patient characteristics, diagnosis-specific information, and indicators of impairment severity are collected. Core clinical assessments include the 10-Meter Walk Test and the Goal Attainment Scaling. Data from each Lokomat® training session are automatically collected.

Results

At time of analysis, the database contained data collected from 595 patients (cerebral palsy: n = 208; stroke: n = 129; spinal cord injury: n = 93; traumatic brain injury: n = 39; and various other diagnoses: n = 126). At onset, average walking speeds were slow. The training intensity increased from the first to the final therapy session and most patients achieved their goals.

Conclusions

The characteristics of the patients matched epidemiological data for the target populations. When patient characteristics differed from epidemiological data, this was mainly due to the selection criteria used to assess eligibility for Lokomat® training. While patients included in randomized controlled interventional trials have to fulfill many inclusion and exclusion criteria, the only selection criteria applying to patients in the ARTIC database are those required for use of the Lokomat®. We suggest that the ARTIC network offers an opportunity to investigate the clinical application and effectiveness of rehabilitation technologies for various diagnoses. Due to the standardization of assessments and the use of a common technology, this network could serve as a basis for researchers interested in specific interventional studies expanding beyond the Lokomat®.

Retraining walking adaptability following incomplete spinal cord injury

Introduction

Functional walking requires the ability to modify one’s gait pattern to environmental demands and task goals—gait adaptability. Following incomplete spinal cord injury (ISCI), gait rehabilitation such as locomotor training (Basic-LT) emphasizes intense, repetitive stepping practice. Rehabilitation approaches focusing on practice of gait adaptability tasks have not been established for individuals with ISCIs but may promote recovery of higher level walking skills. The primary purpose of this case series was to describe and determine the feasibility of administering a gait adaptability retraining approach—Adapt-LT—by comparing the dose and intensity of Adapt-LT to Basic-LT.

Case presentation

Three individuals with ISCIs (>1 year, AIS C or D) completed three weeks each (15 sessions) of Basic-LT and Adapt-LT. Interventions included practice on a treadmill with body weight support and practice overground (≥30 mins total). Adapt-LT focused on speed changes, obstacle negotiation, and backward walking. Training parameters (step counts, speeds, perceived exertion) were compared and outcomes assessed pre and post interventions. Based on completion of the protocol and similarities in training parameters in the two interventions, it was feasible to administer Adapt-LT with a similar dosage and intensity as Basic-LT. Additionally, the participants demonstrated gains in walking function and balance following each training type.

Discussion

Rehabilitation that includes stepping practice with adaptability tasks is feasible for individuals with ISCIs. Further investigation is needed to determine the efficacy of Adapt-LT.

Non-gait-specific intervention for the rehabilitation of walking after SCI: role of the arms

Arm movements modulate leg activity and improve gait efficiency; however, current rehabilitation interventions focus on improving walking through gait-specific training and do not actively involve the arms. The goal of this project was to assess the effect of a rehabilitation strategy involving simultaneous arm and leg cycling on improving walking after incomplete spinal cord injury (iSCI). We investigated the effect of 1) non-gait-specific training and 2) active arm involvement during training on changes in over ground walking capacity. Participants with iSCI were assigned to simultaneous arm-leg cycling (A&L) or legs only cycling (Leg) training paradigms, and cycling movements were assisted with electrical stimulation. Overground walking speed significantly increased by 0.092 ± 0.022 m/s in the Leg group and 0.27 ± 0.072m/s in the A&L group after training. Whereas the increases in the Leg group were similar to those seen after current locomotor training strategies, increases in the A&L group were significantly larger than those in the Leg group. Walking distance also significantly increased by 32.12 ± 8.74 m in the Leg and 91.58 ± 36.24 m in the A&L group. Muscle strength, sensation, and balance improved in both groups; however, the A&L group had significant improvements in most gait measures and had more regulated joint kinematics and muscle activity after training compared with the Leg group. We conclude that electrical stimulation-assisted cycling training can produce significant improvements in walking after SCI. Furthermore, active arm involvement during training can produce greater improvements in walking performance. This strategy may also be effective in people with other neural disorders or diseases. NEW & NOTEWORTHY This work challenges concepts of task-specific training for the rehabilitation of walking and encourages coordinated training of the arms and legs after spinal cord injury. Cycling of the legs produced significant improvements in walking that were similar in magnitude to those reported with gait-specific training. Moreover, active engagement of the arms simultaneously with the legs generated nearly double the improvements obtained by leg training only. The cervico-lumbar networks are critical for the improvement of walking.

Strategies to augment volitional and reflex function may improve locomotor capacity following incomplete spinal cord injury

Many studies highlight the remarkable plasticity demonstrated by spinal circuits following an incomplete spinal cord injury (SCI). Such plasticity can contribute to improvements in volitional motor recovery, such as walking function, although similar mechanisms underlying this recovery may also contribute to the manifestation of exaggerated responses to afferent input, or spastic behaviors. Rehabilitation interventions directed toward augmenting spinal excitability have shown some initial success in improving locomotor function. However, the potential effects of these strategies on involuntary motor behaviors may be of concern. In this article, we provide a brief review of the mechanisms underlying recovery of volitional function and exaggerated reflexes, and the potential overlap between these changes. We then highlight findings from studies that explore changes in spinal excitability during volitional movement in controlled conditions, as well as altered kinematic and behavioral performance during functional tasks. The initial focus will be directed toward recovery of reflex and volitional behaviors following incomplete SCI, followed by recent work elucidating neurophysiological mechanisms underlying patterns of static and dynamic muscle activation following chronic incomplete SCI during primarily single-joint movements. We will then transition to studies of locomotor function and the role of altered spinal integration following incomplete SCI, including enhanced excitability of specific spinal circuits with physical and pharmacological interventions that can modulate locomotor output. The effects of previous and newly developed strategies will need to focus on changes in both volitional function and involuntary spastic reflexes for the successful translation of effective therapies to the clinical setting.

Effects of Training Intensity on Locomotor Performance in Individuals With Chronic Spinal Cord Injury: A Randomized Crossover Study

BACKGROUND

Many physical interventions can improve locomotor function in individuals with motor incomplete spinal cord injury (iSCI), although the training parameters that maximize recovery are not clear. Previous studies in individuals with other neurologic injuries suggest the intensity of locomotor training (LT) may positively influence walking outcomes. However, the effects of intensity during training of individuals with iSCI have not been tested.

OBJECTIVE

The purpose of this pilot, blinded-assessor randomized trial was to evaluate the effects of LT intensity on walking outcomes in individuals with iSCI.

METHODS

Using a crossover design, ambulatory participants with iSCI >1 year duration performed either high- or low-intensity LT for ≤20 sessions over 4 to 6 weeks. Four weeks following completion, the training interventions were alternated. Targeted intensities focused on achieving specific ranges of heart rate (HR) or ratings of perceived exertion (RPE), with intensity manipulated by increasing speeds or applying loads.

RESULTS

Significantly greater increases in peak treadmill speeds (0.18 vs 0.02 m/s) and secondary measures of metabolic function and overground speed were observed following high- versus low-intensity training, with no effects of intervention order. Moderate to high correlations were observed between differences in walking speed or distances and differences in HRs or RPEs during high- versus low-intensity training.

CONCLUSION

This pilot study provides the first evidence that the intensity of stepping practice may be an important determinant of LT outcomes in individuals with iSCI. Whether such training is feasible in larger patient populations and contributes to improved locomotor outcomes deserves further consideration.

Longitudinal Recovery and Reduced Costs After 120 Sessions of Locomotor Training for Motor Incomplete Spinal Cord Injury

OBJECTIVE

To determine the impact of long-term, body weight-supported locomotor training after chronic, incomplete spinal cord injury (SCI), and to estimate the health care costs related to lost recovery potential and preventable secondary complications that may have occurred because of visit limits imposed by insurers.

DESIGN

Prospective observational cohort with longitudinal follow-up.

SETTING

Eight outpatient rehabilitation centers that participate in the Christopher & Dana Reeve Foundation NeuroRecovery Network (NRN).

PARTICIPANTS

Individuals with motor incomplete chronic SCI (American Spinal Injury Association Impairment Scale C or D; N=69; 0.1-45y after SCI) who completed at least 120 NRN physical therapy sessions.

INTERVENTIONS

Manually assisted locomotor training (LT) in a body weight-supported treadmill environment, overground standing and stepping activities, and community integration tasks.

MAIN OUTCOME MEASURES

International Standards for Neurological Classification of Spinal Cord Injury motor and sensory scores, orthostatic hypotension, bowel/bladder/sexual function, Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI), Berg Balance Scale, Modified Functional Reach, 10-m walk test, and 6-minute walk test. Longitudinal outcome measure collection occurred every 20 treatments and at 6- to 12-month follow-up after discharge from therapy.

RESULTS

Significant improvement occurred for upper and lower motor strength, functional activities, psychological arousal, sensation of bowel movement, and SCI-FAI community ambulation. Extended training enabled minimal detectable changes at 60, 80, 100, and 120 sessions. After detectable change occurred, it was sustained through 120 sessions and continued 6 to 12 months after treatment.

CONCLUSIONS

Delivering at least 120 sessions of LT improves recovery from incomplete chronic SCI. Because walking reduces rehospitalization, LT delivered beyond the average 20-session insurance limit can reduce rehospitalizations and long-term health costs.

Body System Effects of a Multi-Modal Training Program Targeting Chronic, Motor Complete Thoracic Spinal Cord Injury

The safety and efficacy of pharmacological and cellular transplantation strategies are currently being evaluated in people with spinal cord injury (SCI). In studies of people with chronic SCIs, it is thought that functional recovery will be best achieved when drug or cell therapies are combined with rehabilitation protocols. However, any functional recovery attributed to the therapy may be confounded by the conditioned state of the body and by training-induced effects on neuroplasticity. For this reason, we sought to investigate the effects of a multi-modal training program on several body systems. The training program included body-weight-supported treadmill training for locomotion, circuit resistance training for upper body conditioning, functional electrical stimulation for activation of sublesional muscles, and wheelchair skills training for overall mobility. Eight participants with chronic, thoracic-level, motor-complete SCI completed the 12-week training program. After 12 weeks, upper extremity muscular strength improved significantly for all participants, and some participants experienced improvements in function, which may be explained by increased strength. Neurological function did not change. Changes in pain and spasticity were highly variable between participants. This is the first demonstration of the effect of this combination of four training modalities. However, balancing participant and study-site burden with capturing meaningful outcome measures is also an important consideration.

Modulation of corticospinal input to the legs by arm and leg cycling in people with incomplete spinal cord injury

The spinal cervico-lumbar interaction during rhythmic movements in humans has recently been studied; however, the role of arm movements in modulating the corticospinal drive to the legs is not well understood. The goals of this study were to investigate the effect of active rhythmic arm movements on the corticospinal drive to the legs (study 1) and assess the effect of simultaneous arm and leg training on the corticospinal pathway after incomplete spinal cord injury (iSCI) (study 2). In study 1, neurologically intact (NI) participants or participants with iSCI performed combinations of stationary and rhythmic cycling of the arms and legs while motor evoked potentials (MEPs) were recorded from the vastus lateralis (VL) muscle. In the NI group, arm cycling alone could facilitate the VL MEP amplitude, suggesting that dynamic arm movements strongly modulate the corticospinal pathway to the legs. No significant difference in VL MEP between conditions was found in participants with iSCI. In study 2, participants with iSCI underwent 12 wk of electrical stimulation-assisted cycling training: one group performed simultaneous arm and leg (A&L) cycling and the other legs-only cycling. MEPs in the tibialis anterior (TA) muscle were compared before and after training. After training, only the A&L group had a significantly larger TA MEP, suggesting increased excitability in the corticospinal pathway. The findings demonstrate the importance of arm movements in modulating the corticospinal drive to the legs and suggest that active engagement of the arms in lower limb rehabilitation may produce better neural regulation and restoration of function.NEW & NOTEWORTHY This study aimed to demonstrate the importance of arm movements in modulating the corticospinal drive to the legs. It provides direct evidence in humans that active movement of the arms could facilitate corticospinal transmission to the legs and, for the first time, shows that facilitation is absent after spinal cord injury. Active engagement of the arms in lower limb rehabilitation increased the excitability of the corticospinal pathway and may produce more effective improvement in leg function.

Slow Versus Fast Robot-Assisted Locomotor Training After Severe Stroke: A Randomized Controlled Trial

BACKGROUND AND PURPOSE

Robot-assisted locomotor training on a bodyweight-supported treadmill is a rehabilitation intervention that compels repetitive practice of gait movements. Standard treadmill speed may elicit rhythmic movements generated primarily by spinal circuits. Slower-than-standard treadmill speed may elicit discrete movements, which are more complex than rhythmic movements and involve cortical areas.

OBJECTIVE

Compare effects of fast (i.e., rhythmic) versus slow (i.e., discrete) robot-assisted locomotor training on a bodyweight-supported treadmill in subjects with chronic, severe gait deficit after stroke.

METHODS

Subjects (N = 18) were randomized to receive 30 sessions (5 d/wk) of either fast or slow robot-assisted locomotor training on a bodyweight-supported treadmill in an inpatient setting. Functional ambulation category, time up and go, 6-min walk test, 10-m walk test, Berg Balance Scale, and Fugl-Meyer Assessment were administered at baseline and postintervention.

RESULTS

The slow group had statistically significant improvement on functional ambulation category (first quartile-third quartile, P = 0.004), 6-min walk test (95% confidence interval [CI] = 1.8 to 49.0, P = 0.040), Berg Balance Scale (95% CI = 7.4 to 14.8, P < 0.0001), time up and go (95% CI = -79.1 to 5.0, P < 0.0030), and Fugl-Meyer Assessment (95% CI = 24.1 to 45.1, P < 0.0001). The fast group had statistically significant improvement on Berg Balance Scale (95% CI = 1.5 to 10.5, P = 0.02).

CONCLUSIONS

In initial stages of robot-assisted locomotor training on a bodyweight-supported treadmill after severe stroke, slow training targeting discrete movement may yield greater benefit than fast training.

Type and Timing of Rehabilitation Following Acute and Subacute Spinal Cord Injury: A Systematic Review

OBJECTIVES

The objective of this study was to conduct a systematic review of the literature to address the following clinical questions: In adult patients with acute and subacute complete or incomplete traumatic SCI, (1) does the time interval between injury and commencing rehabilitation affect outcome?; (2) what is the comparative effectiveness of different rehabilitation strategies, including different intensities and durations of treatment?; (3) are there patient or injury characteristics that affect the efficacy of rehabilitation?; and (4) what is the cost-effectiveness of various rehabilitation strategies?

METHODS

A systematic search was conducted for literature published through March 31, 2015 that evaluated rehabilitation strategies in adults with acute or subacute traumatic SCI at any level. Studies were critically appraised individually and the overall strength of evidence was evaluated using methods proposed by the GRADE (Grades of Recommendation Assessment, Development and Evaluation) working group.

RESULTS

The search strategy yielded 384 articles, 19 of which met our inclusion criteria. Based on our results, there was no difference between body weight-supported treadmill training and conventional rehabilitation with respect to improvements in Functional Independence Measure (FIM) Locomotor score, Lower Extremity Motor Scores, the distance walked in 6 minutes or gait velocity over 15.2 m. Functional electrical therapy resulted in slightly better FIM Motor, FIM Self-Care, and Spinal Cord Independence Measure Self-Care subscores compared with conventional occupational therapy. Comparisons using the Toronto Rehabilitation Institute Hand Function Test demonstrated no differences between groups in 7 of 9 domains. There were no clinically important differences in Maximal Lean Test, Maximal Sidewards Reach Test, T-shirt Test, or the Canadian Occupational Performance Measure between unsupported sitting training and standard in-patient rehabilitation.

CONCLUSION

The current evidence base for rehabilitation following acute and subacute spinal cord injury is limited. Methodological challenges have contributed to this and further research is still needed.

Short-duration, high-intensity bouts of physical therapy to increase self-efficacy, confidence, and function in an individual with incomplete spinal cord injury: A case report

High intensity and frequency of task-specific practice is required to produce functional change in individuals with neurologic conditions. Self-efficacy is an important predictor of engagement in physical activity in individuals with spinal cord injury. Combining these two rehabilitation concepts has the potential for lasting functional improvement. The purpose of this case report is to describe the management of a patient with incomplete spinal cord injury (iSCI) using a model of concentrated bouts of physical therapy with an emphasis on techniques to increase self-efficacy. The patient is a 70-yr old female who sustained C5/C6 vertebral fractures in a fall, resulting in incomplete tetraplegia. She participated in a pilot program of 1 week of intensive physical therapy every 10-12 weeks over the course of 5.5 months. Interventions included functional activities important to the patient, therapeutic exercise, and home exercise program. Confidence and self-efficacy were shaped using patient-directed discussions and active problem solving. The patient improved on all measures of gait, balance, and participation, and also reported increased confidence and self-management of her condition. A high-intensity, periodic model of care delivery combined with a capacity-building approach may be an effective method to improve confidence, motivation, and function in persons with iSCI.

Repeat Exposure to Leg Swing Perturbations During Treadmill Training Induces Long-Term Retention of Increased Step Length in Human SCI: A Pilot Randomized Controlled Study

OBJECTIVE

To determine whether repeat exposure to force perturbations during treadmill training can induce long-term retention of improved step length and overall improvements in locomotor function in persons with spinal cord injury.

DESIGN

Fourteen patients with spinal cord injury were recruited and randomly assigned to swing resistance or swing assistance training groups. A controlled swing resistance or assistance force, for resistance or assistance training groups, respectively, was applied to both legs through a cable-driven robotic system during treadmill training. Each participant trained 3 times per week for 6 weeks. Step length, walking speed, 6-minute walking distance, and other clinical assessments were evaluated before and after 6 weeks of training and 8 weeks after the end of training.

RESULTS

A significant increase in step length was observed after 6 weeks of resistance training (P = 0.04). Step length tended to increase after assistance treadmill training, but the change was not significant (P = 0.18). The changes in step length and functional gains had no significant difference between 2 groups.

CONCLUSIONS

Repeat exposure to swing resistance during treadmill training may induce a prolonged retention of increased step length, although it remains unclear whether swing resistance versus assistance is more effective in inducing increased step length.

Effects of Activity-Based Therapy Interventions on Mobility, Independence, and Quality of Life for People with Spinal Cord Injuries: A Systematic Review and Meta-Analysis

The aim of this study was to review the literature about the effects of activity-based therapy (ABT) interventions on mobility, functional independence, and quality of life for people with a spinal cord injury (SCI). A systematic review with meta-analysis of randomized and non-randomized trials was performed, including adults with a non-progressive SCI at any level. The intervention of interest was ABT, defined as any intervention that sought to improve muscle activation or sensory function below the level of injury in the spinal cord and does not rely on compensatory mechanisms for improving function. The comparison was either no intervention or conventional physical interventions targeted to regions above the level of injury. The outcome measures were quality-of-life questionnaires, mobility assessments, and functional independence scales. Nineteen trials were included in this systematic review. Three compared ABT to no intervention and 16 to conventional physical rehabilitation. The methodological quality of the trials was assessed using the PEDro scale as moderate. Six studies investigated the effects of ABT interventions for the upper limbs, 11 investigated gait-related interventions, and two applied multi-modal interventions. Compared with no intervention, the meta-analysis found that ABT was not more effective for improving independence or lower limb mobility, but conferred a large positive effect on upper limb function. Compared with conventional physical interventions, there was no significant effect of ABT on lower limb mobility, independence, or quality of life; however, it had positive effects on upper limbs. In conclusion, there is evidence that ABT can improve independence and functional ability when applied to the upper limbs in people with SCI. However, it is not superior to conventional physical interventions when applied to the lower limbs.

Preserved gait kinematics during controlled body unloading

Background

Body weight supported locomotor training was shown to improve walking function in neurological patients and is often performed on a treadmill. However, walking on a treadmill does not mimic natural walking for several reasons: absent self-initiation, less active retraction of leg required and altered afferent input. The superiority of overground training has been suggested in humans and was shown in rats demonstrating greater plasticity especially in descending pathways compared to treadmill training. We therefore developed a body weight support system allowing unrestricted overground walking with minimal interfering forces to train neurological patients. The present study investigated the influence of different amounts of body weight support on gait in healthy individuals.

Methods

Kinematic and electromyographic data of 19 healthy individuals were recorded during overground walking at different levels of body weight support (0, 10, 20, 30, 40, and 50%). Upper body inclination, lower body joint angles and multi-joint coordination as well as time-distance parameters were calculated. Continuous data were analyzed with regard to distinct changes within a gait cycle across all unloading conditions.

Results

Temporal gait parameters were most sensitive to changes in body unloading while spatial variables (step length, joint angles) showed modest responses when unloaded by as much as 50% body weight. The activation of the gastrocnemius muscle showed a gradual decrease with increasing unloading while the biceps femoris muscle showed increased activity levels at 50% unloading. These changes occurred during stance phase while swing phase activity remained unaltered.

Conclusions

Healthy individuals were able to keep their walking kinematics strikingly constant even when unloaded by half of their body weight, suggesting that the weight support system permits a physiological gait pattern. However, maintaining a given walking speed using close-to-normal kinematics while being unloaded was achieved by adapting muscle activity patterns. Interestingly, the required propulsion to maintain speed was not achieved by means of increased gastrocnemius activity at push-off, but rather through elevated biceps femoris activity while retracting the leg during stance phase. It remains to be investigated to what extent neurological patients with gait disorders are able to adapt their gait pattern in response to body unloading.

Robot-assisted gait training (Lokomat) improves walking function and activity in people with spinal cord injury: a systematic review

Abstract

Robot-assisted gait training (RAGT) after spinal cord injury (SCI) induces several different neurophysiological mechanisms to restore walking ability, including the activation of central pattern generators, task-specific stepping practice and massed exercise. However, there is no clear evidence for the optimal timing and efficacy of RAGT in people with SCI. The aim of our study was to assess the effects of RAGT on improvement in walking-related functional outcomes in patients with incomplete SCI compared with other rehabilitation modalities according to time elapsed since injury. This review included 10 trials involving 502 participants to meta-analysis. The acute RAGT groups showed significantly greater improvements in gait distance, leg strength, and functional level of mobility and independence than the over-ground training (OGT) groups. The pooled mean difference was 45.05 m (95% CI 13.81 to 76.29, P = 0.005, I² = 0%; two trials, 122 participants), 2.54 (LEMS, 95% CI 0.11 to 4.96, P = 0.04, I² = 0%; three trials, 211 participants) and 0.5 (WISCI-II and FIM-L, 95% CI 0.02 to 0.98, P = 0.04, I² = 67%; three trials, 211 participants), respectively. In the chronic RAGT group, significantly greater improvements in speed (pooled mean difference = 0.07 m/s, 95% CI 0.01 to 0.12, P = 0.01, I² = 0%; three trials, 124 participants) and balance measured by TUG (pooled mean difference = 9.25, 95% CI 2.76 to 15.73, P = 0.005, I² = 74%; three trials, 120 participants) were observed than in the group with no intervention. Thus, RAGT improves mobility-related outcomes to a greater degree than conventional OGT for patients with incomplete SCI, particularly during the acute stage. RAGT treatment is a promising technique to restore functional walking and improve locomotor ability, which might enable SCI patients to maintain a healthy lifestyle and increase their level of physical activity.

Trial registration

PROSPERO (CRD 42016037366). Registered 6 April 2016.

Characterization and validation of a split belt treadmill for measuring hindlimb ground-reaction forces in able-bodied and spinalized felines

BACKGROUND

The measurement of ground reaction forces (GRFs) in animals trained to locomote on a treadmill after spinal cord injury (SCI) could prove valuable for evaluating training outcomes; however, quantitative measures of the GRFs in spinal felines are limited.

NEW METHOD

A split belt treadmill was designed and constructed to measure the GRFs of feline hindlimbs during stepping. The treadmill consists of two independent treadmill assemblies, each mounted on a force plate. The design allows measurements of the vertical (Fz), fore-aft (Fy) and mediolateral (Fx) ground-reaction forces for both hindlimbs while the forelimbs are resting on a platform.

RESULTS

Static and dynamic noise tests revealed little to no noise at frequencies below 6Hz. Validation of the force plate measurements with a hand-held force sensor force showed good agreement between the two force readings. Peak normalized (to body mass) vertical GRFs for intact cats were 4.89±0.85N/kg for the left hindlimb and 4.79±0.97N/kg for the right. In comparison, trained spinalized cats peak normalized vertical GRFs were 2.20±0.94N/kg for the left hindlimb and 2.85±0.99N/kg for the right.

COMPARISON WITH OTHER EXISTING METHODS

Previous methods of measuring GRFs used stationary single force plates or treadmill mounted to single force plate. Using independent treadmills for each hindlimb allows measurement of the individual hindlimb's GRFs in spinalized cats following body-weight supported treadmill training.

CONCLUSIONS

The split belt force treadmill enables the simultaneous recording of ground-reaction forces for both hindlimbs in cats prior to spinalization, and following spinalization and body-weight-supported treadmill training (BWST).

What Is Being Trained? How Divergent Forms of Plasticity Compete To Shape Locomotor Recovery after Spinal Cord Injury

Spinal cord injury (SCI) is a devastating syndrome that produces dysfunction in motor and sensory systems, manifesting as chronic paralysis, sensory changes, and pain disorders. The multi-faceted and heterogeneous nature of SCI has made effective rehabilitative strategies challenging. Work over the last 40 years has aimed to overcome these obstacles by harnessing the intrinsic plasticity of the spinal cord to improve functional locomotor recovery. Intensive training after SCI facilitates lower extremity function and has shown promise as a tool for retraining the spinal cord by engaging innate locomotor circuitry in the lumbar cord. As new training paradigms evolve, the importance of appropriate afferent input has emerged as a requirement for adaptive plasticity. The integration of kinematic, sensory, and loading force information must be closely monitored and carefully manipulated to optimize training outcomes. Inappropriate peripheral input may produce lasting maladaptive sensory and motor effects, such as central pain and spasticity. Thus, it is important to closely consider the type of afferent input the injured spinal cord receives. Here we review preclinical and clinical input parameters fostering adaptive plasticity, as well as those producing maladaptive plasticity that may undermine neurorehabilitative efforts. We differentiate between passive (hindlimb unloading [HU], limb immobilization) and active (peripheral nociception) forms of aberrant input. Furthermore, we discuss the timing of initiating exposure to afferent input after SCI for promoting functional locomotor recovery. We conclude by presenting a candidate rapid synaptic mechanism for maladaptive plasticity after SCI, offering a pharmacological target for restoring the capacity for adaptive spinal plasticity in real time.

Dose-Response Outcomes Associated with Different Forms of Locomotor Training in Persons with Chronic Motor-Incomplete Spinal Cord Injury

Outcomes of training are thought to be related to the amount of training (training dose). Although various approaches to locomotor training have been used to improve walking function in persons with spinal cord injury (SCI), little is known about the relationship between dose of locomotor training and walking outcomes. This secondary analysis aimed to identify the relationship between training dose and improvement in walking distance and speed associated with locomotor training in participants with chronic motor-incomplete spinal cord injury (MISCI). We compared the dose-response relationships associated with each of four different locomotor training approaches. Participants were randomized to either: treadmill-based training with manual assistance (TM = 17), treadmill-based training with stimulation (TS = 18), overground training with stimulation (OG = 15), and treadmill-based training with locomotor robotic device assistance (LR = 14). Subjects trained 5 days/week for 12 weeks, with a target of 60 training sessions. The distance-dose and time-dose were calculated based on the total distance and total time, respectively, participants engaged in walking over all sessions combined. Primary outcome measures included walking distance (traversed in 2 min) and walking speed (over 10 m). Only OG training showed a good correlation between distance-dose and change in walking distance and speed walked over ground (r = 0.61, p = 0.02; r = 0.62, p = 0.01). None of the treadmill-based training approaches were associated with significant correlations between training dose and improvement of functional walking outcome. The findings suggest that greater distance achieved over the course of OG training is associated with better walking outcomes in the studied population. Further investigation to identify the essential elements that determine outcomes would be valuable for guiding rehabilitation.

Overground Locomotor Training in Spinal Cord Injury: A Performance-Based Framework

Background: Locomotor training (LT) is the most commonly used treatment to improve walking performance following spinal cord injury (SCI). The advancement of LT treatments requires the addition of integrative models accounting for the numerous systems responsible for the recovery of walking function following SCI. Objective: This perspective monograph aims to (a) describe a performance-based framework for overground LT (OLT), (b) describe principles of adaptation and motor learning used to inform OLT program design, and (c) present an example OLT program based on the proposed framework. Methods: Individuals with chronic motor-incomplete SCI (7 male, 1 female) classified according to the American Spinal Injury Association Impairment Scale (AIS) as C and D were included. OLT included two 90-minute sessions performed over 12 weeks for a total of 24 sessions. Outcomes measures included overground walking speed, walking economy, pulmonary oxygen uptake, and muscle oxygen extraction measured via near-infrared spectroscopy. Results: Preliminary findings demonstrate the potential of OLT, as describe here, to increase overground walking speed, improve walking economy, accelerate processes associated with oxygen delivery and utilization at the rest-to-work transition, and lower oxygen extraction requirements of skeletal muscle during walking in individuals with chronic motor-incomplete SCI. Conclusion: The proposed framework offers a valuable template for LT program design in both clinical and research settings. Further research is necessary to better understand the effects of OLT and how principles of specificity, progressive overload, and variation within the performance-based framework can be manipulated to maximize function, health, and quality of life in SCI.

Supraspinal Control Predicts Locomotor Function and Forecasts Responsiveness to Training after Spinal Cord Injury

Restoration of walking ability is an area of great interest in the rehabilitation of persons with spinal cord injury. Because many cortical, subcortical, and spinal neural centers contribute to locomotor function, it is important that intervention strategies be designed to target neural elements at all levels of the neuraxis that are important for walking ability. While to date most strategies have focused on activation of spinal circuits, more recent studies are investigating the value of engaging supraspinal circuits. Despite the apparent potential of pharmacological, biological, and genetic approaches, as yet none has proved more effective than physical therapeutic rehabilitation strategies. By making optimal use of the potential of the nervous system to respond to training, strategies can be developed that meet the unique needs of each person. To complement the development of optimal training interventions, it is valuable to have the ability to predict future walking function based on early clinical presentation, and to forecast responsiveness to training. A number of clinical prediction rules and association models based on common clinical measures have been developed with the intent, respectively, to predict future walking function based on early clinical presentation, and to delineate characteristics associated with responsiveness to training. Further, a number of variables that are correlated with walking function have been identified. Not surprisingly, most of these prediction rules, association models, and correlated variables incorporate measures of volitional lower extremity strength, illustrating the important influence of supraspinal centers in the production of walking behavior in humans.

Effects of Overground Locomotor Training on Walking Performance in Chronic Cervical Motor Incomplete Spinal Cord Injury: A Pilot Study

OBJECTIVE

To determine the effects of a novel overground locomotor training program on walking performance in people with chronic cervical motor incomplete spinal cord injury (iSCI).

DESIGN

Before-after pilot study.

SETTING

Human performance research laboratory.

PARTICIPANTS

Adults (N=6, age >18y) with chronic cervical iSCI with American Spinal Injury Association Impairment Scale grades C and D.

INTERVENTIONS

Overground locomotor training included two 90-minute sessions per week for 12 to 15 weeks. Training sessions alternated between uniplanar and multiplanar stepping patterns. Each session was comprised of 5 segments: joint mobility, volitional muscle activation, task isolation, task integration, and activity rehearsal.

MAIN OUTCOME MEASURES

Overground walking speed, oxygen consumption (V˙o₂), and carbon dioxide production (V˙co₂).

RESULTS

Overground locomotor training increased overground walking speed (.36±.20 vs .51±.24 m/s, P<.001, d=.68). Significant decreases in V˙o₂ (6.6±1.3 vs 5.7±1.4mL·kg·min, P=.038, d=.67) and V˙co₂ (753.1±125.5 vs 670.7±120.3mL/min, P=.036, d=.67) during self-selected constant work rate treadmill walking were also noted after training.

CONCLUSIONS

The overground locomotor training program used in this pilot study is feasible and improved both overground walking speed and walking economy in a small sample of people with chronic cervical iSCI. Future studies are necessary to establish the efficacy of this overground locomotor training program and to differentiate among potential mechanisms contributing to enhanced walking performance in people with iSCI after overground locomotor training.

Effectiveness of Automated Locomotor Training in Patients with Acute Incomplete Spinal Cord Injury: A Randomized, Controlled, Multicenter Trial

The aim of this study was to evaluate whether the effect of longer training times (50 instead of 25 min per day) using a robotic device results in a better outcome of walking ability of subjects with a subacute motor complete (American Spinal Injury Association Impairment Scale [AIS]-B) and incomplete (AIS-C) spinal cord injury. Twenty-one patients were enrolled in the study, whereof 18 completed, on average, 34 trainings in 8 weeks. Longer training times resulted in better locomotor function. The second important result of the study is that a beneficial effect can be achieved by the application of a robotic device for prolonged training sessions without requiring more personal resources. It has to remain open whether even longer training times (more than 50 min) would result in a still better outcome. In any case, the extent of possible recovery in an individual patient is determined by the level and severity of spinal cord damage.

The Effectiveness and Safety of Exoskeletons as Assistive and Rehabilitation Devices in the Treatment of Neurologic Gait Disorders in Patients with Spinal Cord Injury: A Systematic Review

Study Design Systematic review. Clinical Questions (1) When used as an assistive device, do wearable exoskeletons improve lower extremity function or gait compared with knee-ankle-foot orthoses (KAFOs) in patients with complete or incomplete spinal cord injury? (2) When used as a rehabilitation device, do wearable exoskeletons improve lower extremity function or gait compared with other rehabilitation strategies in patients with complete or incomplete spinal cord injury? (3) When used as an assistive or rehabilitation device, are wearable exoskeletons safe compared with KAFO for assistance or other rehabilitation strategies for rehabilitation in patients with complete or incomplete spinal cord injury? Methods PubMed, Cochrane, and Embase databases and reference lists of key articles were searched from database inception to May 2, 2016, to identify studies evaluating the effectiveness of wearable exoskeletons used as assistive or rehabilitative devices in patients with incomplete or complete spinal cord injury. Results No comparison studies were found evaluating exoskeletons as an assistive device. Nine comparison studies (11 publications) evaluated the use of exoskeletons as a rehabilitative device. The 10-meter walk test velocity and Spinal Cord Independence Measure scores showed no difference in change from baseline among patients undergoing exoskeleton training compared with various comparator therapies. The remaining primary outcome measures of 6-minute walk test distance and Walking Index for Spinal Cord Injury I and II and Functional Independence Measure-Locomotor scores showed mixed results, with some studies indicating no difference in change from baseline between exoskeleton training and comparator therapies, some indicating benefit of exoskeleton over comparator therapies, and some indicating benefit of comparator therapies over exoskeleton. Conclusion There is no data to compare locomotion assistance with exoskeleton versus conventional KAFOs. There is no consistent benefit from rehabilitation using an exoskeleton versus a variety of conventional methods in patients with chronic spinal cord injury. Trials comparing later-generation exoskeletons are needed.

Rehabilitation Strategies after Spinal Cord Injury: Inquiry into the Mechanisms of Success and Failure

Body-weight supported locomotor training (BWST) promotes recovery of load-bearing stepping in lower mammals, but its efficacy in individuals with a spinal cord injury (SCI) is limited and highly dependent on injury severity. While animal models with complete spinal transections recover stepping with step-training, motor complete SCI individuals do not, despite similarly intensive training. In this review, we examine the significant differences between humans and animal models that may explain this discrepancy in the results obtained with BWST. We also summarize the known effects of SCI and locomotor training on the muscular, motoneuronal, interneuronal, and supraspinal systems in human and non-human models of SCI and address the potential causes for failure to translate to the clinic. The evidence points to a deficiency in neuronal activation as the mechanism of failure, rather than muscular insufficiency. While motoneuronal and interneuronal systems cannot be directly probed in humans, the changes brought upon by step-training in SCI animal models suggest a beneficial re-organization of the systems' responsiveness to descending and afferent feedback that support locomotor recovery. The literature on partial lesions in humans and animal models clearly demonstrate a greater dependency on supraspinal input to the lumbar cord in humans than in non-human mammals for locomotion. Recent results with epidural stimulation that activates the lumbar interneuronal networks and/or increases the overall excitability of the locomotor centers suggest that these centers are much more dependent on the supraspinal tonic drive in humans. Sensory feedback shapes the locomotor output in animal models but does not appear to be sufficient to drive it in humans.

Non-invasive brain stimulation and robot-assisted gait training after incomplete spinal cord injury: A randomized pilot study

BACKGROUND

Locomotor training with a robot-assisted gait orthosis (LT-RGO) and transcranial direct current stimulation (tDCS) are interventions that can significantly enhance motor performance after spinal cord injury (SCI). No studies have investigated whether combining these interventions enhances lower extremity motor function following SCI.

OBJECTIVE

Determine whether active tDCS paired with LT-RGO improves lower extremity motor function more than a sham condition, in subjects with motor incomplete SCI.

METHODS

Fifteen adults with SCI received 36 sessions of either active (n = 9) or sham (n = 6) tDCS (20 minutes) preceding LT-RGO (1 hour). Outcome measures included manual muscle testing (MMT; primary outcome measure); 6-Minute Walk Test (6MinWT); 10-Meter Walk Test (10MWT); Timed Up and Go Test (TUG); Berg Balance Scale (BBS); and Spinal Cord Independence Measure-III (SCIM-III).

RESULTS

MMT showed significant improvements after active tDCS, with the most pronounced improvement in the right lower extremity. 10MWT, 6MinWT, and BBS showed improvement for both groups. TUG and SCIM-III showed improvement only for the sham tDCS group.

CONCLUSION

Pairing tDCS with LT-RGO can improve lower extremity motor function more than LT-RGO alone. Future research with a larger sample size is recommended to determine longer-term effects on motor function and activities of daily living.

Transvertebral direct current stimulation paired with locomotor training in chronic spinal cord injury: A case study

STUDY DESIGN

This double-blind, sham-controlled, crossover case study combined transvertebral direct current stimulation (tvDCS) and locomotor training on a robot-assisted gait orthosis (LT-RGO).

OBJECTIVE

Determine whether cathodal tvDCS paired with LT-RGO leads to greater changes in function and neuroplasticity than sham tvDCS paired with LT-RGO.

SETTING

University of Kentucky (UK) HealthCare Stroke and Spinal Cord Neurorehabilitation Research at HealthSouth Cardinal Hill Hospital.

METHODS

A single subject with motor incomplete spinal cord injury (SCI) participated in 24 sessions of sham tvDCS paired with LT-RGO before crossover to 24 sessions of cathodal tvDCS paired with LT-RGO. Functional outcomes were measured with 10 Meter Walk Test (10MWT), 6 Minute Walk Test (6MWT), Spinal Cord Independence Measure-III (SCIM-III) mobility component, lower extremity manual muscle test (MMT), and Berg Balance Scale (BBS). Corticospinal changes were assessed using transcranial magnetic stimulation.

RESULTS

Improvement in 10MWT speed, SCIM-III mobility component, and BBS occurred with both conditions. 6MWT worsened after sham tvDCS and improved after cathodal tvDCS. MMT scores for both lower extremities improved following sham tvDCS but decreased following cathodal tvDCS. Corticospinal excitability increased following cathodal tvDCS but not sham tvDCS.

CONCLUSION

These results suggest that combining cathodal tvDCS and LT-RGO may improve functional outcomes, increase corticospinal excitability, and possibly decrease spasticity. Randomized controlled trials are needed to confirm these conclusions.

SPONSORSHIP

This publication was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1TR000117, and the HealthSouth Cardinal Hill Stroke and Spinal Cord Endowment (1215375670).

Long-Term Training with a Brain-Machine Interface-Based Gait Protocol Induces Partial Neurological Recovery in Paraplegic Patients

Brain-machine interfaces (BMIs) provide a new assistive strategy aimed at restoring mobility in severely paralyzed patients. Yet, no study in animals or in human subjects has indicated that long-term BMI training could induce any type of clinical recovery. Eight chronic (3–13 years) spinal cord injury (SCI) paraplegics were subjected to long-term training (12 months) with a multi-stage BMI-based gait neurorehabilitation paradigm aimed at restoring locomotion. This paradigm combined intense immersive virtual reality training, enriched visual-tactile feedback, and walking with two EEG-controlled robotic actuators, including a custom-designed lower limb exoskeleton capable of delivering tactile feedback to subjects. Following 12 months of training with this paradigm, all eight patients experienced neurological improvements in somatic sensation (pain localization, fine/crude touch, and proprioceptive sensing) in multiple dermatomes. Patients also regained voluntary motor control in key muscles below the SCI level, as measured by EMGs, resulting in marked improvement in their walking index. As a result, 50% of these patients were upgraded to an incomplete paraplegia classification. Neurological recovery was paralleled by the reemergence of lower limb motor imagery at cortical level. We hypothesize that this unprecedented neurological recovery results from both cortical and spinal cord plasticity triggered by long-term BMI usage.

The effects of backward walking training on balance and mobility in an individual with chronic incomplete spinal cord injury: A case report

BACKGROUND/PURPOSE

Individuals with incomplete spinal cord injuries (ISCIs) commonly face persistent gait impairments. Backward walking training may be a useful rehabilitation approach, providing novel gait and balance challenges. However, little is known about the effects of this approach for individuals with ISCIs. The purpose of this case report was to describe the effects of backward walking training on strength, balance, and upright mobility in an individual with chronic ISCI.

METHODS

A 28-year-old female, 11-years post ISCI (C4, AIS D) completed 18-sessions of backward walking training on a treadmill with partial body-weight support and overground. Training emphasized stepping practice, speed, and kinematics. Outcome measures included: Lower Extremity Motor Score, Berg Balance Scale (BBS), Sensory Organization Test (SOT), 10-Meter Walk Test (10MWT), 3-meter backward walking test, Timed Up and Go (TUG), and Activities-Specific Balance Confidence (ABC) Scale.

RESULTS

Strength did not change. Improved balance was evident based on BBS (20 to 37/56) and SOT scores (27 to 40/100). Upright mobility improved based on TUG times (57 to 32.7 s), increased 10MWT speed (0.23 to 0.31 m/s), and backward gait speed (0.07 to 0.12 m/s). Additionally, self-reported balance confidence (ABC Scale) increased from 36.9% to 49.6%.

CONCLUSIONS

The results suggest that backward walking may be a beneficial rehabilitation approach; examination of the clinical efficacy is warranted.

Repetitive Intermittent Hypoxia and Locomotor Training Enhances Walking Function in Incomplete Spinal Cord Injury Subjects: A Randomized, Triple-Blind, Placebo-Controlled Clinical Trial

Incomplete spinal cord injuries (iSCI) leave spared synaptic pathways below the level of injury. Intermittent hypoxia (IH) elicits plasticity in the spinal cord and strengthens spared synaptic pathways, expressed as respiratory and somatic functional recovery in experimental animals and humans with iSCI. This study is a randomized, triple-blind, two-arm parallel clinical trial performed in Santiago, Chile. We compared the effects of a 4-week protocol of IH combined with body weight-supported treadmill training (BWSTT), with continuous normoxia (Nx) and BWSTT on 10-meter walk test (10MWT), 6-minute walk test (6MWT), and timed up and go (TUG) test in American Spinal Injury Association C and D individuals with iSCI. Subjects received daily IH (cycling 9%/21% O₂ every 1.5 min, 15 cycles/day) or continuous Nx (21% O₂) combined with 45 min BWSTT for 5 consecutive days, followed by IH/Nx 3 × per week (3 × wIH/Nx) for 3 additional weeks. Subjects were assessed at day 5, weekly from weeks 2-4, and at a 2-week follow-up. Daily IH plus BWSTT enhanced walking speed, expressed as decreased 10MWT time at day 5 versus baseline (IH: -10.2 ± 3.0 vs. Nx: -1.7 ± 1.7 sec, p = 0.006), and walking endurance expressed as increased 6MWT distance at day 5 versus baseline (IH: 43.0 ± 10.7 vs. Nx: 6.1 ± 3.4 m, p = 0.012), but not TUG time. Further, 3 × wIH maintained the daily IH-induced walking speed, and enhanced the daily IH-induced walking endurance, which is maintained up to the 2-week follow-up. We conclude that daily IH enhances walking recovery in subjects with iSCI, confirming previous findings. Moreover, 3 × wIH prolonged or enhanced daily IH-induced walking speed and endurance improvements, respectively, up to 5 weeks post-daily IH. Repetitive IH may be a safe and effective therapeutic alternative for persons with iSCI.

Visuotemporal cues clinically improved walking ability of ambulatory patients with spinal cord injury within 5 days

BACKGROUND/OBJECTIVE

The human movement system uses a variety of inputs to produce movements. The concurrent use of external information, specifically visutemporal cues, while walking could promote the walking ability of ambulatory patients with spinal cord injury (SCI). This study explored the use of visutemporal cues in rehabilitation training by subjecting ambulatory individuals with SCI to walking training with or without visuotemporal cues and then assessing the effects on their functional ability.

DESIGN

Quasi-experimental study.

SETTING

A tertiary rehabilitation center.

PARTICIPANTS

Thirty-two participants were randomly assigned to the experimental or control groups using stage of injury, severity of SCI, and baseline walking ability as criteria for group arrangement (16 participants/group).

INTERVENTIONS

The participants were trained to walk over level ground at their fastest safe speed with or without a visuotemporal cue, 30 minutes/day, for 5 consecutive days.

OUTCOME MEASURES

The 10-meter walk test, 6-minute walk test, timed up and go test, and five times sit-to-stand test.

RESULTS

The participants demonstrated significant improvement in all functional tests after the 5 days of training (P < 0.001). In addition, the improvement in the group trained using the visuotemporal cue was significantly better than that trained without using the cue.

CONCLUSIONS

Most of these participants were at a chronic stage of SCI, so the findings supported a benefit for incorporating visuotemporal cues in rehabilitation practice, particularly today when the length of rehabilitation has dramatically decreased.

A Review on Locomotor Training after Spinal Cord Injury: Reorganization of Spinal Neuronal Circuits and Recovery of Motor Function

Locomotor training is a classic rehabilitation approach utilized with the aim of improving sensorimotor function and walking ability in people with spinal cord injury (SCI). Recent studies have provided strong evidence that locomotor training of persons with clinically complete, motor complete, or motor incomplete SCI induces functional reorganization of spinal neuronal networks at multisegmental levels at rest and during assisted stepping. This neuronal reorganization coincides with improvements in motor function and decreased muscle cocontractions. In this review, we will discuss the manner in which spinal neuronal circuits are impaired and the evidence surrounding plasticity of neuronal activity after locomotor training in people with SCI. We conclude that we need to better understand the physiological changes underlying locomotor training, use physiological signals to probe recovery over the course of training, and utilize established and contemporary interventions simultaneously in larger scale research studies. Furthermore, the focus of our research questions needs to change from feasibility and efficacy to the following: what are the physiological mechanisms that make it work and for whom? The aforementioned will enable the scientific and clinical community to develop more effective rehabilitation protocols maximizing sensorimotor function recovery in people with SCI.

Gait recovery following spinal cord injury in mice: Limited effect of treadmill training

BACKGROUND

Several studies in rodents with complete spinal cord transections have demonstrated that treadmill training improves stepping movements. However, results from studies in incomplete spinal cord injured animals have been conflicting and questions regarding the training dosage after injury remain unresolved.

OBJECTIVES

To assess the effects of treadmill-training regimen (20 minutes daily, 5 days a week) for 3, 6 or 9 weeks on the recovery of locomotion in hemisected SCI mice.

METHODS

A randomized and blinded controlled experimental trial used a mouse model of incomplete spinal cord injury (SCI). After a left hemisection at T10, adult male mice were randomized to trained or untrained groups. The trained group commenced treadmill training one week after surgery and continued for 3, 6 or 9 weeks. Quantitative kinematic gait analysis was used to assess the spatiotemporal characteristics of the left hindlimb prior to injury and at 1, 4, 7 and 10 weeks post-injury.

RESULTS

One week after injury there was no movement of the left hindlimb and some animals dragged their foot. Treadmill training led to significant improvements in step duration, but had limited effect on the hindlimb movement pattern. Locomotor improvements in trained animals were most evident at the hip and knee joints whereas recovery of ankle movement was limited, even after 9 weeks of treadmill training.

CONCLUSION

These results demonstrate that treadmill training may lead to only modest improvement in recovery of hindlimb movement after incomplete spinal cord injury in mice.

A Systematic Review of Experimental Strategies Aimed at Improving Motor Function after Acute and Chronic Spinal Cord Injury

While various approaches have been proposed in clinical trials aimed at improving motor function after spinal cord injury in humans, there is still limited information regarding the scope, methodological quality, and evidence associated with single-intervention and multi-intervention approaches. A systematic review performed using the PubMed search engine and the key words "spinal cord injury motor recovery" identified 1973 records, of which 39 were selected (18 from the search records and 21 from reference list inspection). Study phase ( clinicaltrials.org criteria) and methodological quality (Cochrane criteria) were assessed. Studies included proposed a broad range of single-intervention (encompassing cell therapies, pharmacology, electrical stimulation, rehabilitation) (encompassing cell therapies, pharmacology, electrical stimulation, rehabilitation) and multi-intervention approaches (that combined more than one strategy). The highest evidence level was for Phase III studies supporting the role of multi-intervention approaches that contained a rehabilitation component. Quality appraisal revealed that the percentage of selected studies classified with high risk of bias by Cochrane criteria was as follows: random sequence generation = 64%; allocation concealment = 77%; blinding of participants and personnel = 69%; blinding of outcome assessment = 64%; attrition = 44%; selective reporting = 44%. The current literature contains a high proportion of studies with a limited ability to measure efficacy in a valid manner because of low methodological strength in all items of the Cochrane risk of bias assessment. Recommendations to decrease bias are discussed and include increased methodological rigor in the study design and recruitment of study participants, and the use of electrophysiological and imaging measures that can assess functional integrity of the spinal cord (and may be sufficiently sensitive to detect changes that occur in response to therapeutic interventions).

Variability in responsiveness to interventions in people with spinal cord injury: Do some respond better than others?

Spinal cord injury (SCI) results in significant impairments in function and ankle joint spasticity is a common secondary complication. Various interventions have been trialed to improve function and reduce spasticity after SCI, with variable results. We investigated the effects of a pharmacological (an anti-spastic medication - tizanidine) and a physical intervention (robotic-assisted locomotor training - Lokomat) on function in people with incomplete SCI over 4-week of training. The outcome measures were walking speed, endurance and mobility. Subjects were randomized into one of three groups; no intervention (control), Lokomat (Lok) and tizanidine (Tiz). To account for variability, we used growth mixture modelling (GMM) to class subjects based on their recovery patterns. GMM identified two classes of recovery: high and low function. Significant improvements were seen in walking speed and mobility in high and low functioning subjects in the Lok group, and in walking endurance in high functioning subjects in the Tiz group. However, changes with training were clinically important only for approximately 10% of subjects, who achieved a minimal important difference (MID) in functional outcomes as a result of the training. We used mixed model ANOVAs to compare the group effects. Improvements with training were seen in both classes, however no differences between interventions were found. The GMM had classed all subjects that achieved the MID as high functioning. GMM can be used to successfully class subjects; however larger subject numbers and longer interventions are required to fully utilize this technique. Our results demonstrate that both interventions have potential to improve walking capacity, but more intense training for a longer period may need to achieve MID.

Optimizing learning of a locomotor task: amplifying errors as needed

Research on motor learning has emphasized that errors drive motor adaptation. Thereby, several researchers have proposed robotic training strategies that amplify movement errors rather than decrease them. In this study, the effect of different robotic training strategies that amplify errors on learning a complex locomotor task was investigated. The experiment was conducted with a one degree-of freedom robotic stepper (MARCOS). Subjects were requested to actively coordinate their legs in a desired gait-like pattern in order to track a Lissajous figure presented on a visual display. Learning with three different training strategies was evaluated: (i) No perturbation: the robot follows the subjects' movement without applying any perturbation, (ii) Error amplification: existing errors were amplified with repulsive forces proportional to errors, (iii) Noise disturbance: errors were evoked with a randomly-varying force disturbance. Results showed that training without perturbations was especially suitable for a subset of initially less-skilled subjects, while error amplification seemed to benefit more skilled subjects. Training with error amplification, however, limited transfer of learning. Random disturbing forces benefited learning and promoted transfer in all subjects, probably because it increased attention. These results suggest that learning a locomotor task can be optimized when errors are randomly evoked or amplified based on subjects' initial skill level.

Interventions to Reduce Spasticity and Improve Function in People With Chronic Incomplete Spinal Cord Injury: Distinctions Revealed by Different Analytical Methods

BACKGROUND

Spinal cord injury (SCI) results in impaired function, and ankle joint spasticity is a common secondary complication. Different interventions have been trialed with variable results.

OBJECTIVE

We investigated the effects of pharmacological and physical (locomotor training) interventions on function in people living with incomplete motor function loss caused by SCI and used different analytical techniques to understand whether functional levels affect recovery with different interventions.

METHODS

Participants with an incomplete SCI were assigned to 3 groups: no intervention, Lokomat, or tizanidine. Outcome measures were the 10-m walk test, 6-minute walk test, and the Timed Up and Go. Participants were classified in 2 ways: (1) based on achieving an improvement above the minimally important difference (MID) and (2) using growth mixture modeling (GMM). Functional levels of participants who achieved the MID were compared and random coefficient regression (RCR) was used to assess recovery in GMM classes.

RESULTS

Overall, walking speed and endurance improved, with no difference between interventions. Only a small number of participants achieved the MID. Both MID and GMM-RCR analyses revealed that tizanidine improved endurance in high-functioning participants. GMM-RCR classification also showed that speed and mobility improved after locomotor training.

CONCLUSIONS

Improvements in function were achieved in a limited number of people with SCI. Using the MID and GMM techniques, differences in responses to interventions between high-and low-functioning participants could be identified. These techniques may, therefore, have potential to be used for characterizing therapeutic effects resulting from different interventions.

Neuromechanical principles underlying movement modularity and their implications for rehabilitation

Neuromechanical principles define the properties and problems that shape neural solutions for movement. Although the theoretical and experimental evidence is debated, we present arguments for consistent structures in motor patterns, i.e., motor modules, that are neuromechanical solutions for movement particular to an individual and shaped by evolutionary, developmental, and learning processes. As a consequence, motor modules may be useful in assessing sensorimotor deficits specific to an individual and define targets for the rational development of novel rehabilitation therapies that enhance neural plasticity and sculpt motor recovery. We propose that motor module organization is disrupted and may be improved by therapy in spinal cord injury, stroke, and Parkinson's disease. Recent studies provide insights into the yet-unknown underlying neural mechanisms of motor modules, motor impairment, and motor learning and may lead to better understanding of the causal nature of modularity and its underlying neural substrates.

Effects of Innovative WALKBOT Robotic-Assisted Locomotor Training on Balance and Gait Recovery in Hemiparetic Stroke: A Prospective, Randomized, Experimenter Blinded Case Control Study With a Four-Week Follow-Up

The present clinical investigation was to ascertain whether the effects of WALKBOT-assisted locomotor training (WLT) on balance, gait, and motor recovery were superior or similar to the conventional locomotor training (CLT) in patients with hemiparetic stroke. Thirty individuals with hemiparetic stroke were randomly assigned to either WLT or CLT. WLT emphasized on a progressive, conventional locomotor retraining practice (40 min) combined with the WALKBOT-assisted, haptic guidance and random variable locomotor training (40 min) whereas CLT involved conventional physical therapy alone (80 min). Both intervention dosages were standardized and provided for 80 min, five days/week for four weeks. Clinical outcomes included function ambulation category (FAC), Berg balance scale (BBS), Korean modified Barthel index (K-MBI), modified Ashworth scale (MAS), and EuroQol-5 dimension (EQ-5D) before and after the four-week program as well as at follow-up four weeks after the intervention. Two-way repeated measure ANOVA showed significant interaction effect (time × group) for FAC (p=0.02), BBS (p=0.03) , and K-MBI (p=0.00) across the pre-training, post-training, and follow-up tests, indicating that WLT was more beneficial for balance, gait and daily activity function than CLT alone. However, no significant difference in other variables was observed. This is the first clinical trial that highlights the superior, augmented effects of the WALKBOT-assisted locomotor training on balance, gait and motor recovery when compared to the conventional locomotor training alone in patients with hemiparetic stroke.

Comprehensive assessment of walking function after human spinal cord injury

Regaining any locomotor function after spinal cord injury is not only of immediate importance for affected patients but also for clinical research as it allows to investigate mechanisms underlying motor impairment and locomotor recovery. Clinical scores inform on functional outcomes that are clinically meaningful to value effects of therapy while they all lack the ability to explain underlying mechanisms of recovery. For this purpose, more elaborate recordings of walking kinematics combined with assessments of spinal cord conductivity and muscle activation patterns are required. A comprehensive assessment framework comprising of multiple complementary modalities is necessary. This will not only allow for capturing even subtle changes induced by interventions that are likely missed by standard clinical outcome measures. It will be fundamental to attribute observed changes to naturally occurring spontaneous recovery in contrast to specific changes induced by novel therapeutic interventions beyond the improvements achieved by conventional therapy.

Facilitatory effects of anti-spastic medication on robotic locomotor training in people with chronic incomplete spinal cord injury

Background

The objective of this study was to investigate whether an anti-spasticity medication can facilitate the effects of robotic locomotor treadmill training (LTT) to improve gait function in people with incomplete spinal cord injury (SCI).

Methods

Individuals with chronic incomplete SCI were recruited and carried out a 4 week intervention of either locomotor treadmill training (LTT) alone (n = 26) or LTT combined with Tizanidine (TizLTT), an anti-spasticity medication (n = 22). Gait function was evaluated using clinical outcome measures of gait, speed and endurance. To better understand the underlying mechanisms of the therapeutic effects, maximal strength, active range of motion (AROM) and peak velocity (Vp) of ankle dorsi- and planter-flexor muscles were also measured. Differences were assessed using two-way mixed design analysis of variance. The number of subjects that achieved the minimal important difference (MID) for clinical scores was also measured for each group, and the results of those that did attain the MID were compared with those that did not.

Results

Both LTT and TizLTT resulted in significant improvements in walking speed and dorsiflexion maximum strength, with no significant differences between them, using group-averaging analysis. However, using the MID analysis, a higher proportion of subjects in the TizLTT group achieved the MID for walking speed (40%) compared with LTT alone (13%). Those that achieved the MID for walking speed were significantly higher functioning at baseline than those that did not in the TizLTT group, and the change in walking speed was associated with the change in dorsiflexion peak velocity (R² = 0.40; P < 0.05).

Conclusion

Tizanidine appears to facilitate the effects of LTT on gait function in individuals with chronic SCI that are higher functioning at baseline. We speculate that this may be due to restoration of inhibitory mechanisms by Tizanidine, resulting in greater stretch in the planterflexor muscles during the LTT.

Training conditions that best reproduce the joint powers of unsupported walking

OBJECTIVE

To identify the clinically relevant combinations of body weight support and speed that best reproduce the joint powers of unsupported walking.

METHODS

Timing and magnitude of lower extremity joint powers were calculated for 8 neurologically intact volunteers (4M/4F) walking with 0%, 30% and 50% body weight support at three speeds (slow, comfortable, and fast). Lower extremity joint power absorption was analyzed during weight acceptance and forward propulsion. In addition, power generation was analyzed during forward propulsion. Timings and magnitudes of joint powers per condition were evaluated to identify the training combinations of body weight support and speed that best preserved the powers of unsupported walking at slow, comfortable and fast speeds.

RESULTS

For all speeds examined, increasing body weight support to 30% without changing speed provided the best match. In general, changes in speed disrupted the joint power magnitudes and timings more than application of body weight support. Increasing body weight support when faster training speeds were used proved a viable method for reproducing the joint powers of slow, unsupported walking.

CONCLUSIONS

These data provide a reference for understanding the effect of potential training conditions on power absorption and generation within the lower extremity joints during walking. It is possible to reproduce the joint powers of unsupported walking with certain combinations of body weight support and speed. We recommend applying adequate levels of BWS when training speeds are faster than the overground speed goal, as occurs during treadmill-based locomotor rehabilitation of individuals with incomplete spinal cord injury.