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Background: Powered exoskeletons provide a way to stand and walk for people with severe spinal cord injury. Here, we used the ReWalk exoskeleton to determine the training dosage required for walking proficiency, the sensory and motor changes in the nervous system with training, and the functionality of the device in a home-like environment., Methods: Participants with chronic (> 1 yr) motor complete or incomplete spinal cord injury, who were primarily wheelchair users, were trained to walk in the ReWalk for 12 weeks. Measures were taken before, during, immediately after, and 2-3 months after training. Measures included walking progression, sitting balance, skin sensation, spasticity, and strength of the corticospinal tracts., Results: Twelve participants were enrolled with 10 completing training. Training progression and walking ability: The progression in training indicated about 45 sessions to reach 80% of final performance in training. By the end of training, participants walked at speeds of 0.28-0.60 m/s, and distances of 0.74-1.97 km in 1 h. The effort of walking was about 3.3 times that for manual wheelchair propulsion. One non-walker with an incomplete injury became a walker without the ReWalk after training. Sensory and motor measures: Sitting balance was improved in some, as seen from the limits of stability and sway speed. Neuropathic pain showed no long term changes. Change in spasticity was mixed with suggestion of differences between those with high versus low spasticity prior to training. The strength of motor pathways from the brain to back extensor muscles remained unchanged. Adverse events: Minor adverse events were encountered by the participants and trainer (skin abrasions, non-injurious falls). Field testing: The majority of participants could walk on uneven surfaces outdoors. Some limitations were encountered in home-like environments., Conclusion: For individuals with severe SCI, walking proficiency in the ReWalk requires about 45 sessions of training. The training was accompanied by functional improvements in some, especially in people with incomplete injuries., Trial Registration: NCT02322125 Registered 22 December 2014.

Objective: To describe the development of structure, process and outcome indicators that will advance the quality of walking rehabilitation for Canadians with spinal cord injury or disease (SCI/D) by 2020. Method: A framework for the evaluation of the quality of walking rehabilitation was developed by experts in walking after SCI/D. A systematic literature review identified factors influencing walking outcomes and potential walking indicators. A Driver diagram analysis summarized the factors affecting walking outcomes and subsequently informed the selection of structure and process indicators. Psychometric properties and clinical utility of potential walking indicators were considered during the selection of outcome indicators. Results: The structure indicator is the number of physical therapists using evidence-based walking interventions per number of ambulatory individuals with SCI/D. The process indicator is the number of received hours of walking interventions during inpatient rehabilitation per number of ambulatory individuals with SCI/D. The intermediary outcome indicator, which is collected at discharge from inpatient rehabilitation, is either the modified Timed Up and Go or the 10-Meter Walk Test, the choice of measure is dictated by the stage of walking recovery, as defined by the Standing and Walking Assessment Tool. The final outcome indicator, collected at 18 months post-discharge, is the Spinal Cord Independence Measure III-Mobility subscale. Conclusion: The selected indicators align with current clinical practice in Canada. The indicators will direct the timing and enhance the volume of walking therapy delivered, to ultimately increase the proportion of patients who achieve their walking potential by 18 months post-rehabilitation.

Background: Powered exoskeletons for over ground walking were designed to help people with neurological impairments to walk again. Extended training in powered exoskeletons has led to changes in walking and physiological functions. Few studies have considered the perspective of the participants. The users' perspective is vital for adoption of assistive devices. We explored the expectations and experiences of persons with spinal cord injury, training with the ReWalk exoskeleton., Methods: A qualitative research design with individual interviews was used. Eleven participants with spinal cord injury, taking part in 12 weeks of 4 times weekly training using the ReWalk, were interviewed before, immediately after, and 2 months after training. Interviews were audio recorded and transcribed verbatim. A six stage approach to thematic analysis was used., Results: The theme consistently expressed was the exoskeleton allowed participants to do everyday activities, like everyone else, such as looking people in the eye or walking outside. Their experiences were captured in three categories: 1) learning, a description of both expectations for learning and perspectives on how learning occurred; 2) changing, perspectives on perceived changes with training; and 3) contributing, which captured participant perspectives on contributing to research, including the giving of direct feedback regarding the exoskeleton (i.e., what worked and what could be changed)., Conclusions: Incorporating the view of the user in the design and refinement of exoskeletons will help ensure that the devices are appropriate for future users. Availability and support for the use of exoskeleton devices in community settings is an interim step to home use as the devices continue to improve., Trial Registration: www.clinicaltrials.gov ( NCT02322125 ). Registered Dec 22, 2014 - Retrospectively registered after the first 4 participants had enrolled in the study.

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.

The neural plasticity of spinal reflexes after two contrasting forms of walking training was determined in individuals with chronic, motor-incomplete spinal cord injury (SCI). Endurance Training involved treadmill walking for as long as possible, and Precision Training involved walking precisely over obstacles and onto targets overground. Twenty participants started either Endurance or Precision Training for 2 months and then crossed over after a 2-month rest period to the other form of training for 2 months. Measures were taken before and after each phase of training and rest. The cutaneomuscular reflex (CMR) during walking was evoked in the soleus (SOL) and tibialis anterior muscles by stimulating the posterior tibial nerve at the ankle. Clonus was estimated from the EMG power in the SOL during unperturbed walking. The inhibitory component of the SOL CMR was enhanced after Endurance but not Precision Training. Clonus did not change after either form of training. Participants with lower reflex excitability tended to be better walkers (i.e., faster walking speeds) prior to training, and the reduction in clonus was significantly correlated with the improvement in walking speed and distance. Thus, reflex excitability responded in a training-specific way, with the reduction in reflex excitability related to improvements in walking function. Trial registration number is NCT01765153., Competing Interests: Atif Khan has no competing interests, financial or otherwise. Susan Patrick's salary is covered by Canadian Institute of Health Research grant awarded to Jaynie Yang during the conduct of the study. Francois Roy has no competing interests, financial or otherwise. Monica Gorassini received a grant from Canadian Institute of Health Research and Alberta Paraplegic Association. Jaynie Yang received grants from Canadian Institutes of Health Research, Christopher and Dana Reeve Foundation, Alberta Paraplegic Foundation, and Rick Hansen Institute during the conduct of the study.

After incomplete spinal cord injury (iSCI), training of walking function that emphasizes both endurance and speed may produce different changes in spared neural pathways compared to precision training that emphasizes walking over obstacles and precise placement of the foot. To examine this, 16 participants with iSCI received 2 months of endurance or precision training, in random order, with 2 months of rest before crossing-over to the other type of training. Both forms of training increased the maximum motor-evoked potential (MEPmax) elicited by transcranial magnetic stimulation over the motor cortex, but only in tibialis anterior (TA) muscles that had small (<0.5 mV) MEPmax values before training, no matter when the specific type of training was performed. A similar pattern of training-induced increases in maximum voluntary contractions was also observed. Although walking function was improved by both forms of training, a positive correlation between MEPmax and clinical measures of walking function only occurred after endurance training. Endurance and precision training also increased the excitability of inhibitory spinal networks, as demonstrated by an increase in the suppression of TA MEPs by a prior, low-threshold stimulation to the common peroneal nerve and by increases in the inhibitory component of the cutaneomuscular reflex. The increase in the descending excitation of the spinal cord and the increase in excitability of inhibitory spinal networks may mediate the improved volitional control of walking and reduction of involuntary muscle spasticity, respectively, that are observed in response to intensive motor training in participants with incomplete spinal cord injury., (© 2015 Elsevier B.V. All rights reserved.)

Background: Retraining walking following spinal cord injury using visually guided tasks may be especially efficacious because it engages the motor cortex, whose input may facilitate improvements in functional walking., Objectives: To contrast 2 methods of retraining, one emphasizing precise, visually guided walking over obstacles and on targets (Precision Training), the other emphasizing mass practice of walking on a treadmill (Endurance Training)., Methods: A randomized, single-blind, crossover design was used. Twenty-two participants, ≥7 months postinjury, were randomly allocated to start with Precision or Endurance Training. Each phase of training was 5 times per week for 2 months, followed by a 2-month rest., Measures: of walking speed, distance, skill, confidence, and depression were obtained before training, then monthly thereafter., Results: Both forms of training led to significant improvements in walking, with Endurance Training inducing bigger improvements in walking distance than Precision Training, especially for high-functioning walkers who had initial walking speeds >0.5 m/s. The largest improvements in walking speed and distance occurred in the first month of Endurance Training, with minimal changes in the second month of training. In contrast, improvements in walking skill occurred over both months during both types of training. Retention of over ground walking speed, distance, and skill was excellent for both types of training., Conclusions: Intensive walking training in the chronic phase after spinal cord injury is effective in improving over ground walking. Visually guided tasks for training individuals with chronic spinal cord injury were not superior to mass practice on a treadmill.

Background: The Spinal Cord Injury Functional Ambulation Profile (SCI-FAP) is a valid, reliable measure of walking skill (eg, walking while negotiating obstacles, doors, and stairs)., Objective: The responsiveness of the SCI-FAP was assessed at least 7 months after spinal cord injury (SCI) and compared with that of the 10-Meter Walk Test (10MWT) and the Six-Minute Walk Test (6MWT)., Design: A secondary analysis of data collected during a randomized, single-blind, crossover trial was performed., Methods: Participants had incomplete SCI and could walk at least 5 m without manual assistance. After 3 or 4 baseline assessments, participants completed 2 months of precision training (stepping over obstacles and onto targets on the ground) and 2 months of endurance training (treadmill training with body weight support, if needed). Walking function was assessed with the SCI-FAP, 10MWT, and 6MWT. Internal responsiveness was evaluated through change scores and standardized response means (SRMs). External responsiveness was gauged by correlating change scores on the SCI-FAP, 10MWT, and 6MWT. The minimal detectable change was calculated from the standard error of measurement from the baseline assessments., Results: The SCI-FAP scores improved with both interventions. The magnitude of change was greater for participants whose pretraining self-selected speed was less than 0.5 m/s. The SCI-FAP had moderate SRMs. The 10MWT (fastest speed) and 6MWT had the largest SRMs after precision training and endurance training, respectively. The minimal detectable change in the SCI-FAP was 96 points., Limitations: The convenience sample was small and all participants could ambulate independently (with devices); therefore, the generalizability of the findings is limited., Conclusions: The SCI-FAP was responsive to changes in walking ability in participants who had incomplete SCI and walked at slow speeds, but overall the 10MWT and 6MWT were more responsive.

Objectives: (1) To provide clinicians with the best evidence for effective retraining of walking after spinal cord injury (SCI) to achieve over ground walking. (2) To identify gaps in our knowledge to guide future research., Methods: Articles that addressed the retraining of walking in adults with SCI and reported outcome measures of over ground walking ability were identified through a non-systematic search of the PubMed, Scopus, and CINAHL databases. No restriction was applied to the method of training. Selected articles were appraised using the Physiotherapy Evidence Database scale. Information was synthesized to answer who best responds to what type of treatment, how that treatment should be delivered, and at what stage after injury., Results: Individuals with motor incomplete SCI (American Spinal Injury Association (ASIA) Impairment scale (AIS) C and D) are most likely to regain walking over ground. The effective methods of training all involved a substantial component of walking in the training, and if assistance was provided, partial assistance was more effective than total assistance. Walking training resulted in a change in over ground walking speed of 0.06-0.77 m/s, and 6 minute walk distance of 24-357 m. The effective training schedules ranged from 10 to 130 sessions, with a density of sessions ranging from 2 per week to 5 per week. Earlier training led to superior results both in the subacute (<6 months) and chronic phases (>6 months) after injury, but even individuals with chronic injuries of long duration can improve., Conclusions: Frequent, early treatment for individuals with motor incomplete SCI using walking as the active ingredient whether on the treadmill or over ground, generally leads to improved walking over ground. Much work remains for the future, including better quantification of treatment intensity, better outcome measures to quantify a broader range of walking skills, and better ways to retrain individuals with more severe lesions (AIS A and B).

Background: It is unclear which individuals with incomplete spinal cord injury best respond to body-weight-supported treadmill training., Objective: The purpose of this study was to determine the factors that predict whether a person with motor incomplete spinal cord injury will respond to body-weight-supported treadmill training., Design: This was a prognostic study with a one-group pretest-posttest design., Methods: Demographic, clinical, and electrophysiological measurements taken prior to training were examined to determine which measures best predicted improvements in walking speed in 19 individuals with chronic (>7 months postinjury), motor-incomplete spinal cord injuries (ASIA Impairment Scale categories C and D, levels C1-L1)., Results: Two initial measures correlated significantly with improvements in walking speed: (1) the ability to volitionally contract a muscle, as measured by the lower-extremity manual muscle test (LE MMT) (r=.72), and (2) the peak locomotor electromyographic (EMG) amplitude in the legs (r=.56). None of the demographics (time since injury, age, body mass index) were significantly related to improvements in walking speed, nor was the clinical measure of balance (Berg Balance Scale). Further analysis of LE MMT scores showed 4 key muscle groups were significantly related to improvements in walking speed: knee extensors, knee flexors, ankle plantar flexors, and hip abductors (r=.82). Prediction using the summed MMT scores from those muscles and peak EMG amplitude in a multivariable regression indicated that peak locomotor EMG amplitude did not add significantly to the prediction provided by the LE MMT alone. Change in total LE MMT scores from the beginning to the end of training was not correlated with a change in walking speed over the same period., Limitations: The sample size was limited, so the results should be considered exploratory., Conclusions: The results suggest that preserved muscle strength in the legs after incomplete spinal cord injury, as measured by MMT, allows for improvements in walking speed induced by locomotor training.

An incomplete spinal cord injury (SCI) impairs neural conduction along spared ascending sensory pathways to disrupt the control of residual motor movements. To characterize how SCI affects the activation of the motor cortex by spared ascending sensory pathways, we examined how stimulation of leg afferents facilitates the excitability of the motor cortex in subjects with incomplete SCI. Homo- and heteronymous afferents to the tibialis anterior (TA) representation in the motor cortex were electrically stimulated, and the responses were compared with uninjured controls. In addition, we examined if cortical excitability could be transiently increased by repetitively pairing stimulation of spared ascending sensory pathways with transcranial magnetic stimulation (TMS), an intervention termed paired associative stimulation (PAS). In uninjured subjects, activating the tibial nerve at the ankle 45-50 ms before a TMS pulse in a conditioning-test paradigm facilitated the motor-evoked potential (MEP) in the heteronymous TA muscle by twofold on average. In contrast, prior tibial nerve stimulation did not facilitate the TA MEP in individuals with incomplete SCI (n = 8 SCI subjects), even in subjects with less severe injuries. However, we provide evidence that ascending sensory inputs from the homonymous common peroneal nerve (CPN) can, unlike the heteronymous pathways, facilitate the motor cortex to modulate the TA MEP (n = 16 SCI subjects) but only in subjects with less severe injuries. Finally, by repetitively coupling CPN stimulation with coincident TA motor cortex activation during PAS, we show that 7 of 13 SCI subjects produced appreciable (>20%) facilitation of the MEP following the intervention. The increase in corticospinal tract excitability by PAS was transient (<20 min) and tended to be more prevalent in SCI subjects with stronger functional ascending sensory pathways.

Background and Purpose: Walking in the home and community is an important goal for individuals with incomplete spinal cord injury (iSCI). Walking in the community requires various skills, such as negotiating curbs, doors, and uneven terrain. This case report describes the use of a method to retrain walking overground that is intensive, variable, and relevant to daily walking (skill training). The aims of this case series were to determine the effectiveness of skill training in a small group of people with iSCI and to compare skill training with body-weight-supported treadmill training (BWSTT) in the same individuals., Case Description: Four individuals who were a median of 2.7 years (interquartile range [IQR]=12.8) after iSCI participated in alternating phases of intervention, each 3 months long. All patients started with BWSTT. Two patients subsequently engaged in skill training while the other 2 patients engaged in BWSTT, after which a third phase of intervention (opposite to the second) was repeated., Outcomes: The Modified Emory Functional Ambulation Profile, the 10-Meter Walk Test, the 6-Minute Walk Test, the Berg Balance Scale, and the Activities-specific Balance Confidence Scale were administered before training, monthly throughout training, and 3 months after training., Discussion: Overall improvements in walking speed met or exceeded the minimal clinically important difference for individuals with iSCI (> or = 0.05 m/s), particularly during the skill training phase (skill training: median=0.09 m/s, IQR=0.13; BWSTT: median=0.01 m/s, IQR=0.07). Walking endurance, obstacle clearance, and stair climbing also improved with both types of intervention. Three of the 4 patients had retained their gains at follow-up (retention of walking speed: median=92%, IQR=63%). Thus, the findings suggest that skill training was effective in this small group of individuals.

Intensive treadmill training after incomplete spinal cord injury can improve functional walking abilities. To determine the changes in muscle activation patterns that are associated with improvements in walking, we measured the electromyography (EMG) of leg muscles in 17 individuals with incomplete spinal cord injury during similar walking conditions both before and after training. Specific differences were observed between subjects that eventually gained functional improvements in overground walking (responders), compared with subjects where treadmill training was ineffective (nonresponders). Although both groups developed a more regular and less clonic EMG pattern on the treadmill, it was only the tibialis anterior and hamstring muscles in the responders that displayed increases in EMG activation. Likewise, only the responders demonstrated decreases in burst duration and cocontraction of proximal (hamstrings and quadriceps) muscle activity. Surprisingly, the proximal muscle activity in the responders, unlike nonresponders, was three- to fourfold greater than that in uninjured control subjects walking at similar speeds and level of body weight support, suggesting that the ability to modify muscle activation patterns after injury may predict the ability of subjects to further compensate in response to motor training. In summary, increases in the amount and decreases in the duration of EMG activity of specific muscles are associated with functional recovery of walking skills after treadmill training in subjects that are able to modify muscle activity patterns following incomplete spinal cord injury.

Objective: Gait retraining should target the walking skills most needed for independence in the home and community. The main objective of this study was to document the walking tasks most commonly encountered in daily life by able-bodied adults. The study also compared participation in walking tasks between able-bodied adults and persons with incomplete spinal cord injuries., Participants: Convenience sample of 50 able-bodied adults and 16 ambulatory, community-dwelling persons with incomplete spinal cord injuries., Methods: A walking survey was developed, and its content validity and concurrent validity confirmed. Participants used the survey to document the frequency with which walking tasks were encountered during a full waking day., Results: Frequently encountered tasks included walking on smooth and rough surfaces, opening/closing doors and carrying objects. Tasks encountered more than once per day by the majority of able-bodied participants included negotiating obstacles, walking on uneven and sloped surfaces, in crowded environments, narrow spaces, and on steps and stairs. Participants with spinal cord injuries encountered fewer tasks, including many of those frequently encountered by able-bodied participants., Conclusion: The findings identify the important walking tasks for ambulation in the home and community. These tasks should be included in therapy programs aiming to retrain functional walking.

In this update, the authors will discuss evidence for both spinal and brain regulation of walking in humans. They will consider the sensory control of walking in young babies and spinal cord-injured adults, two models with weak descending input from the brain, to suggest that subcortical structures are important in shaping walking behavior. Based on evidence from development, the authors suggest that the primitive pattern of walking seen in babies forms the base upon which additional features are added by supraspinal input as independent walking develops. Increasing evidence suggests the motor cortex is important in the control of level-ground walking in adults, in contrast to quadrupeds. This brain input seems particularly important for distal flexors in the leg. Finally, the authors will consider evidence that the recovery of walking after incomplete spinal cord injuries is dependent on the presence of descending input from the motor cortex and our ability to strengthen that input. These findings imply that training methods for improving walking after injury to the nervous system must promote the involvement of both spinal and brain circuits.

Motoneurons in the spinal cord have intrinsic voltage-dependent persistent inward currents (PICs; e.g. persistent calcium currents) that amplify synaptic inputs by three- to five-fold in addition to providing a sustained excitatory drive that allows motoneurons to fire repetitively following a brief synaptic excitation. In this study, we examined whether prolonged involuntary muscle spasms in subjects with long-term injury to the spinal cord are mediated by the activation of PICs in the motoneuron. To examine this in the human, we used a paired motor unit analysis technique where the firing frequency of one motor unit of the pair (control unit) was used to estimate the synaptic drive to the motoneuron pool, including the drive to a second higher-threshold motor unit of the pair (test unit). The degree to which a motoneuron PIC helped to sustain the discharge of a test motor unit (self-sustained firing) was determined from the reduction in control unit firing at de-recruitment (DeltaF) compared with recruitment of the test unit. This DeltaF value corresponds to the reduction in synaptic drive needed to counteract the intrinsic PIC and, thus, was used an indirect measure of this current. In the nine motor unit pairs studied, the average estimated synaptic drive, or control unit firing rate, required to recruit a test motor unit at the onset of a muscle spasm was significantly higher (by 43%) than the estimated synaptic drive during de-recruitment at the end of a muscle spasm. This indicated that a motoneuron PIC, and associated self-sustained firing, facilitated the firing of the test units during the prolonged muscle spasms. In addition, in all subjects tested (seven out of seven), we observed that following a muscle spasm or voluntary contraction, spontaneous and self-sustained firing of motor units could continue for many seconds, even minutes, at very low discharge rates (average 5.2 +/- 1.6 Hz) with extremely low spike-to-spike variability (coefficient of variation = 5.4 +/- 1.6%). Moreover, increases in synaptic drive (noise) to the spontaneously firing units with voluntary muscle contractions or muscle spasms increased both the mean firing rate of the motor units in addition to their firing variability. This suggests that the slow spontaneous firing commonly observed in chronic spinal injury likely occurs without appreciable synaptic noise and is likely driven to a substantial degree by PICs intrinsic to the motoneuron because it is self-sustained and very regular.