Perspectives of parents partnering with physical therapists to deliver intensive rehabilitation for their young children with perinatal stroke: A qualitative study.

BACKGROUND: Parental participation in their young children's rehabilitation has been promoted to increase intervention intensity, but parents' perspectives on increased involvement remain unclear. The objective of this study was to explore parents' experiences partnering with physical therapists (PTs) to administer early, intensive rehabilitation to their young children with cerebral palsy (CP). METHODS: Twelve mothers and one father of children between 8 months and 3 years old with CP were interviewed. Semistructured interviews were conducted before and after parents partnered with a PT to deliver a 12 week activity-based intervention targeting their child's lower extremities. The intervention occurred in the child's home and in PT clinical sites. Interviews were audio recorded and transcribed verbatim. Interpretive description was used as the methodological framework. RESULTS: The three themes were (1) focus on maximizing the child's potential, (2) participation in intensive rehabilitation is challenging, and (3) the importance of a positive experience with therapy. Families discussed a number of barriers and facilitators to participating in intensive rehabilitation. CONCLUSIONS: These results provide considerations for clinicians and researchers to facilitate meaningful engagement of parents in their young children's rehabilitation. This is especially important with increasing evidence for early, activity-based interventions for young children with CP.

Engaging the Lower Extremity via Active Therapy Early (ELEVATE) Is Feasible and May Improve Gross Motor Function in Children with Spastic Bilateral Cerebral Palsy: A Case Series.

Purpose: The feasibility of ELEVATE with respect to adherence and preliminary efficacy was determined for children with spastic bilateral cerebral palsy (CP) from encephalopathy of prematurity. Methods: A case series was used. Participants were randomized to receive ELEVATE immediately or delay the intervention by 3 months before receiving the intervention. The outcomes included feasibility measures of (1) number of children recruited, (2) percentage of sessions attended, (3) stride counts during the intervention, and preliminary efficacy measures of change over the intervention period in (4) Gross Motor Function Measure-66 (GMFM-66), and (5) kinematics and weight-bearing during treadmill walking. Results: Four boys under 3 years of age participated. All participants tolerated 60-minute intervention sessions four times/week for 12 weeks, and attended 75%-94% (min-max) of the targeted sessions. The median step count per session ranged from 833 to 2484 steps (min-max) during the final week of training. Participants showed an increase in GMFM-66 score of 2.4-7.5 points (min-max) over the 3-month intervention phase, as compared to a decrease of 1.7 for one participant and an increase of 1.3 for another over the delay period. Three participants demonstrated small improvements in their gait with the intervention. Conclusions: Engaging young children with bilateral CP in intensive rehabilitation targeting gross motor function was feasible and demonstrated preliminary efficacy. The results have guided the design of a larger clinical trial to assess efficacy of early, active interventions for children with spastic bilateral CP.

Objectif: les chercheurs ont déterminé la faisabilité d'ELEVATE en matière d'adhésion et d'efficacité préliminaire chez des enfants ayant une paralysie cérébrale spastique bilatérale (PC) causée par une encéphalopathie de la prématurité. Méthodologie: série de cas. Les participants ont été choisis au hasard entre l'utilisation immédiate d'ELEVATE ou son report de trois mois. Les résultats incluaient des mesures de fiabilité, soit 1) le nombre d'enfants recrutés, 2) le pourcentage de séances suivies, 3) le compte des foulées pendant l'intervention et les mesures d'efficacité préliminaire pendant la période de l'intervention sur le plan de 4) la mesure de la fonction motrice globale 66 (GMFM-66) et de 5) la cinématique et la mise en charge pendant la marche sur tapis roulant. Résultats: quatre garçons de moins de trois ans ont participé. Tous ont toléré des séances d'intervention de 60 minutes quatre fois par semaine pendant 12 semaines et ont assisté à 75 % à 94 % (minimum-maximum) des séances ciblées. Le compte médian de foulées par séance se situait entre 833 et 2 484 foulées (minimum­maximum) lors de la dernière semaine d'entraînement. Les participants ont présenté une augmentation de 2,4 à 7,5 points (minimum-maximum) au score du GMFM-66 pendant les trois mois de la phase d'intervention, par rapport à une diminution de 1,7 point chez un participant et à une augmentation de 1,3 point chez un autre pendant la période de report. Trois participants ont démonté de légères améliorations de leur démarche grâce à l'intervention. Conclusions: il est faisable de faire participer des jeunes enfants ayant une PC bilatérale à une réadaptation intensive visant la fonction motrice globale, et cette intervention a une efficacité préliminaire démontrée. Les résultats ont entraîné la conception d'une étude clinique plus vaste pour évaluer l'efficacité d'interventions précoces actives chez les enfants ayant une PC bilatérale spastique.

Neural Plasticity in Spinal and Corticospinal Pathways Induced by Balance Training in Neurologically Intact Adults: A Systematic Review.

Balance training, defined here as training of postural equilibrium, improves postural control and reduces the rate of falls especially in older adults. This systematic review aimed to determine the neuroplasticity induced by such training in younger (18-30 years old) and older adults (≥65 years old). We focused on spinal and corticospinal pathways, as studied with electrophysiology, in people without neurological or other systemic disorders. We were specifically interested in the change in the excitability of these pathways before and after training. Searches were conducted in four databases: MEDLINE, CINAHL, Scopus, and Embase. A total of 1,172 abstracts were screened, and 14 articles were included. Quality of the studies was evaluated with the Downs and Black checklist. Twelve of the studies measured spinal reflexes, with ten measuring the soleus H-reflex. The H-reflex amplitude was consistently reduced in younger adults after balance training, while mixed results were found in older adults, with many showing an increase in the H-reflex after training. The differences in results between studies of younger vs. older adults may be related to the differences in their H-reflexes at baseline, with older adults showing much smaller H-reflexes than younger adults. Five studies measured corticospinal and intracortical excitability using transcranial magnetic stimulation. Younger adults showed reduced corticospinal excitability and enhanced intracortical inhibition after balance training. Two studies on older adults reported mixed results after training. No conclusions could be drawn for corticospinal and intracortical plasticity given the small number of studies. Overall, balance training induced measurable change in spinal excitability, with different changes seen in younger compared to older adults.

Parent-therapist partnership to ELEVATE gross motor function in children with perinatal stroke: protocol for a mixed methods randomized controlled trial.

BACKGROUND: There is increasing evidence for early, active rehabilitation to enhance motor function following early brain injury. This is clear for interventions targeting the upper extremity, whereas passive treatment approaches for the lower extremity persist. The purpose of this trial is to evaluate the effectiveness of early, intensive rehabilitation targeting the lower extremity and delivered in a parent-therapist partnership model for children with perinatal stroke. METHODS: We describe a protocol for a waitlist-control, single-blind, mixed methods effectiveness randomized controlled trial, with an embedded qualitative study using interpretative description. Participants are children with perinatal stroke aged eight months to three years with signs of hemiparesis. Participants will be randomly allocated to an immediate ELEVATE (Engaging the Lower Extremity Via Active Therapy Early) intervention group, or a waitlist-control group, who will receive usual care for six months. The ELEVATE intervention involves one hour of training four days per week for 12 weeks, with a pediatric therapist and a parent or guardian each delivering two sessions per week. The intervention targets the affected lower extremity by progressively challenging the child while standing and walking. The primary outcome measure is the Gross Motor Function Measure-66. Secondary outcomes include the Pediatric Quality of Life Inventory™, Young Children's Participation and Environment Measure, and an instrumented measure of spasticity. A cost-effectiveness analysis and qualitative component will explore benefit to costs ratios and parents' perspectives of early, intensive rehabilitation, and their role as a partner in the rehabilitation, respectively. DISCUSSION: This study has the potential to change current rehabilitation for young children with perinatal stroke if the ELEVATE intervention is effective. The parent interviews will provide further insight into benefits and challenges of a partnership model of rehabilitation. The mixed methods design will enable optimization for transfer of this collaborative approach into physical therapy practice. TRIAL REGISTRATION: ClinicalTrials.gov NCT03672864 . Registered 17 September 2018.

Parents' perceptions of functional electrical stimulation as an upper limb intervention for young children with hemiparesis: qualitative interviews with mothers.

BACKGROUND/OBJECTIVE: To explore parents' perceptions of an upper extremity (UE) intervention using functional electrical stimulation (FES) for young children with hemiparesis. METHODS: Parents of children aged 3-6 years with a history of perinatal stroke, impaired UE function, and participation in a 12-week FES intervention delivered at a hospital were included in this exploratory qualitative study. Nine mothers participated in a semi-structured interview < 1 week after their child completed the FES intervention (MyndMove®, MyndTec Inc.) targeting the hemiparetic UE. Open-ended questions queried parents' goals, perceived benefits, and challenges of the FES intervention. Interviews were audio recorded and transcribed verbatim. Qualitative conventional content analysis was used to analyze the transcripts. RESULTS: Five themes were identified. 1) Parents' expectations for the FES intervention. Mothers described setting functional, exploratory, and realistic goals, yet feeling initial apprehension towards FES. 2) Perceived improvement. Physical, functional, and psychological improvements were observed with FES; however, there was still room for improvement. 3) Factors influencing the FES intervention. Program structure, therapist factors, and child factors influenced perceived success. 4) Lack of access to intensive therapy. Mothers noted that FES is not provided in mainstream therapy; however, they wanted access to FES outside of the study. They also highlighted socioeconomic challenges to accessing FES. 5) Strategies to facilitate participation. The mothers provided suggestions for program structure and delivery, and session delivery. CONCLUSIONS: Mothers perceived the FES intervention to have physical, functional and psychological benefits for their children. Interest in continuing with FES highlights a need to improve access to this therapy for young children.

Early, Intensive, Lower Extremity Rehabilitation Shows Preliminary Efficacy After Perinatal Stroke: Results of a Pilot Randomized Controlled Trial.

BACKGROUND: Perinatal stroke injures motor regions of the brain, compromising movement for life. Early, intensive, active interventions for the upper extremity are efficacious, but interventions for the lower extremity remain understudied. OBJECTIVE: To determine the feasibility and potential efficacy of ELEVATE-Engaging the Lower Extremity Via Active Therapy Early-on gross motor function. METHODS: We conducted a single-blind, two-arm, randomized controlled trial (RCT), with the Immediate Group receiving the intervention while the Delay Group served as a 3-month waitlist control. A separate cohort living beyond commuting distance was trained by their parents with guidance from physical therapists. Participants were 8 months to 3 years old, with MRI-confirmed perinatal ischemic stroke and early signs of hemiparesis. The intervention was play-based, focused on weight-bearing, balance and walking for 1 hour/day, 4 days/week for 12 weeks. The primary outcome was the Gross Motor Function Measure-66 (GMFM-66). Secondary outcomes included steps and gait analyses. Final follow-up occurred at age 4. RESULTS: Thirty-four children participated (25 RCT, 9 Parent-trained). The improvement in GMFM-66 over 12 weeks was greater for the Immediate than the Delay Group in the RCT (average change 3.4 units higher) and greater in younger children. Average step counts reached 1370-3750 steps/session in the last week of training for all children. Parent-trained children also improved but with greater variability. CONCLUSIONS: Early, activity-intensive lower extremity therapy for young children with perinatal stroke is feasible and improves gross motor function in the short term. Longer term improvement may require additional bouts of intervention. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov (NCT01773369).

Retraining walking over ground in a powered exoskeleton after spinal cord injury: a prospective cohort study to examine functional gains and neuroplasticity.

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.

Development of Walking indicators to advance the quality of spinal cord injury rehabilitation: SCI-High Project.

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.

Perspectives of people with spinal cord injury learning to walk using a powered exoskeleton.

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.

Validating Accelerometry as a Measure of Arm Movement for Children With Hemiplegic Cerebral Palsy.

BACKGROUND: For children with hemiplegic cerebral palsy (HCP), rehabilitation aims to increase movement of the affected arm. However, no validated measure objectively examines this construct in pediatric practice or daily life. OBJECTIVE: The objective of this study was to evaluate the criterion and known-groups validity of accelerometry as a measure of arm movement in children and adolescents with HCP. DESIGN: This was a prospective cross-sectional study. METHODS: Twenty-seven children and adolescents with typical development (3.4-13.9 years old) and 11 children and adolescents with HCP (4.7-14.7 years old; Manual Ability Classification System rating I or II) wore accelerometers on their wrists while engaged in 20 minutes of play, which included intermittent intervals of stillness and vigorous movement of the arms. Vector magnitude (VM) values identified the presence (VM > 2.0 counts per epoch) and absence (VM ≤ 2.0 counts per epoch) of arm movement for every 2-second epoch. Video was simultaneously recorded; each 2-second interval of footage was scored as "movement" or "no movement" for each arm. RESULTS: Agreement between accelerometry and video observation was greater than or equal to 81%, and the prevalence-adjusted and bias-adjusted κ value was greater than or equal to 0.69 for both groups of participants; these results supported the criterion validity of accelerometry. The ratio of nondominant arm movement to dominant arm movement measured by accelerometry was significantly greater in participants with typical development (mean [SD] = 0.87 [0.09]) than in participants with HCP (mean = 0.78 [0.07]) on the basis of 10 age- and sex-matched pairs; these results supported known-groups validity. LIMITATIONS: The small sample size of the group with HCP prevented the stratification of data by age. Participants with HCP had high or moderately high function of the affected arm; hence, the findings do not apply to children and adolescents with more significant hemiparesis. CONCLUSIONS: Accelerometry is a valid measure of arm movement in children with HCP and children without HCP. These findings contribute to the development of innovative upper limb assessments for children with hemiparesis.

The Feasibility of Functional Electrical Stimulation to Improve Upper Extremity Function in a Two-year-old Child with Perinatal Stroke: A Case Report.

AIMS: To evaluate the effectiveness and feasibility (i.e. tolerability, adherence) of functional electrical stimulation (FES) for the upper extremity (UE) in a two-year-old child with perinatal stroke. METHODS: Forty hours of FES over eight weeks was prescribed. FES to the hemiplegic triceps, extensor carpi radialis longus and brevis, extensor carpi ulnaris and extensor digitorum was timed with reaching during play. Assessments were performed before, during, and two months post-intervention. UE function (Melbourne Assessment 2 (MA2), Assisting Hand Assessment (AHA)) and spasticity (Modified Tardieu with electrogoniometry and electromyography) were measured. The mother completed a semi-structured interview post-intervention. Descriptive statistics were used for adherence and UE measures. A repeated-measures ANOVA compared Modified Tardieu parameters (e.g. catch angle) over time. Conventional content analysis was used for the interview data. RESULTS: The child completed 39.2/40 hours. Immediately post-intervention, improvements were observed on MA2's Range of Motion subscale and catch angle (Modified Tardieu, p < 0.001). Two months post-intervention, improvements were observed on MA2's Accuracy and Fluency subscales. No change in AHA score occurred. Three themes emerged from the interview: (1) Ingredients for program success; (2) Information about the FES device; and (3) The child's response. CONCLUSIONS: UE FES was feasible in a two-year-old child with hemiplegia.

Early Intensive Leg Training to Enhance Walking in Children With Perinatal Stroke: Protocol for a Randomized Controlled Trial.

BACKGROUND: Development of motor pathways is modulated by activity in these pathways, when they are maturing (ie, critical period). Perinatal stroke injures motor pathways, including the corticospinal tracts, reducing their activity and impairing motor function. Current intervention for the lower limb emphasizes passive approaches (stretching, braces, botulinum toxin injections). The study hypothesis was that intensive, early, child-initiated activity during the critical period will enhance connectivity of motor pathways to the legs and improve motor function. OBJECTIVE: The study objective was to determine whether early intervention with intensive activity is better than standard care, intervention delivered during the proposed critical period is better than after, and the outcomes are different when the intervention is delivered by a physical therapist in an institution vs. a parent at home. DESIGN: A prospective, delay-group, single-blind, randomized controlled trial (RCT) and a parallel, cohort study of children living beyond commuting distance and receiving an intervention delivered by their parent. SETTING: The RCT intervention was provided in university laboratories, and parent training was provided in the childs home. PARTICIPANTS: Children 8 months to 3 years old with MRI-confirmed perinatal ischemic stroke and early signs of hemiparesis. INTERVENTION: Intensive, play-based leg activity with weights for the affected leg and foot, 1 hour/day, 4 days/week for 12 weeks. MEASUREMENTS: The primary outcome was the Gross Motor Function Measure-66 score. Secondary outcomes were motion analysis of walking, full-day step counts, motor evoked potentials from transcranial magnetic stimulation, and patellar tendon reflexes. LIMITATIONS: Inter-individual heterogeneity in the severity of the stroke and behavioral differences are substantial but measurable. Differences in intervention delivery and assessment scoring are minimized by standardization and training. CONCLUSIONS: The intervention, contrary to current practice, could change physical therapy interventions for children with perinatal stroke.

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.

Training-Specific Neural Plasticity in Spinal Reflexes after Incomplete Spinal Cord Injury.

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.

Gait Transitions in Human Infants: Coping with Extremes of Treadmill Speed.

Spinal pattern generators in quadrupedal animals can coordinate different forms of locomotion, like trotting or galloping, by altering coordination between the limbs (interlimb coordination). In the human system, infants have been used to study the subcortical control of gait, since the cerebral cortex and corticospinal tract are immature early in life. Like other animals, human infants can modify interlimb coordination to jump or step. Do human infants possess functional neuronal circuitry necessary to modify coordination within a limb (intralimb coordination) in order to generate distinct forms of alternating bipedal gait, such as walking and running? We monitored twenty-eight infants (7-12 months) stepping on a treadmill at speeds ranging between 0.06-2.36 m/s, and seventeen adults (22-47 years) walking or running at speeds spanning the walk-to-run transition. Six of the adults were tested with body weight support to mimic the conditions of infant stepping. We found that infants could accommodate a wide range of speeds by altering stride length and frequency, similar to adults. Moreover, as the treadmill speed increased, we observed periods of flight during which neither foot was in ground contact in infants and in adults. However, while adults modified other aspects of intralimb coordination and the mechanics of progression to transition to a running gait, infants did not make comparable changes. The lack of evidence for distinct walking and running patterns in infants suggests that the expression of different functional, alternating gait patterns in humans may require neuromuscular maturation and a period of learning post-independent walking.

Facilitation of descending excitatory and spinal inhibitory networks from training of endurance and precision walking in participants with incomplete spinal cord injury.

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.

Characteristics of the developing human locomotor system: Similarities to other mammals.

Similarities in the development of locomotion between young children and other mammals are explored by reanalysis of data accrued over ~18 years. Supported stepping in children was tested on a treadmill. Although the time course of development is more protracted in humans compared to other mammals, the same trends are seen. For example, the duration of the stepping cycle shortens rapidly in the first 5 months of life. Hypermetric flexion of the hip and knee during stepping is seen in children <3 mo old. Stability of the locomotor rhythm both with respect to cycle duration within a limb and coupling between limbs improves slowly. Finally, coordination between the left and right legs can be manipulated with training, indicating experience-dependent learning at a young age. The possible reasons for these remarkably similar trends in development are explored as a function of maturational time tables for neural structures.

Prior experience but not size of error improves motor learning on the split-belt treadmill in young children.

Children can modify learned motor skills, such as walking, to adapt to new environments. Movement errors in these new situations drive the learning. We used split-belt walking to determine whether size of the error affects the degree of learning. Twenty-two children (aged 2-5 y) walked on the split-belt treadmill on two separate days spaced 1 week apart. Twenty-eight adults served as controls. On Day 1, children experienced an abrupt change in belt speeds (from 1:1 to 2:1 differential) resulting in large errors, or a gradual change (same change in speed over 12-15 min), resulting in small errors. Learning was measured by the size of the aftereffect upon return to a 1:1 differential. On Day 2 (1 week later), the leg on the fast belt was reversed, as was the method of introducing the speed differential. We found that the error size did not affect learning. Unexpectedly, learning was greater on Day 2 compared to Day 1, especially for children under 4 y of age, despite the fact that the task was opposite to that of Day 1, and did not influence learning in adults. Hence, 11 additional children under 4 y of age were tested with belts running at the same speed on Day 1, and with a 2:1 speed differential (abrupt introduction) on Day 2. Surprisingly, learning was again greater on Day 2. We conclude that size of error during split-belt walking does not affect learning, but experience on a treadmill does, especially for younger children.

Long-latency, inhibitory spinal pathway to ankle flexors activated by homonymous group 1 afferents.

Inhibitory feedback from sensory pathways is important for controlling movement. Here, we characterize, for the first time, a long-latency, inhibitory spinal pathway to ankle flexors that is activated by low-threshold homonymous afferents. To examine this inhibitory pathway in uninjured, healthy participants, we suppressed motor-evoked potentials (MEPs), produced in the tibialis anterior (TA), by a prior stimulation to the homonymous common peroneal nerve (CPN). The TA MEP was suppressed by a triple-pulse stimulation to the CPN, applied 40, 50, and 60 ms earlier and at intensities of 0.5-0.7 times motor threshold (average suppression of test MEP was 33%). Whereas the triple-pulse stimulation was below M-wave and H-reflex threshold, it produced a long-latency inhibition of background muscle activity, approximately 65-115 ms after the CPN stimulation, a time period that overlapped with the test MEP. However, not all of the MEP suppression could be accounted for by this decrease in background muscle activity. Evoked responses from direct activation of the corticospinal tract, at the level of the brain stem or thoracic spinal cord, were also suppressed by low-threshold CPN stimulation. Our findings suggest that low-threshold muscle and cutaneous afferents from the CPN activate a long-latency, homonymous spinal inhibitory pathway to TA motoneurons. We propose that inhibitory feedback from spinal networks, activated by low-threshold homonymous afferents, helps regulate the activation of flexor motoneurons by the corticospinal tract.

Spinal Cord Injury Functional Ambulation Profile: a preliminary look at responsiveness.

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.