Preeti M. Nair

Neuroplasticity After Spinal Cord Injury and Training: An Emerging Paradigm Shift in Rehabilitation and Walking Recovery

Physical rehabilitation after spinal cord injury has been based on the premise that the nervous system is hard-wired and irreparable. Upon this assumption, clinicians have compensated for irremediable sensorimotor deficits using braces, assistive devices, and wheelchairs to achieve upright and seated mobility. Evidence from basic science, however, demonstrates that the central nervous system after injury is malleable and can learn, and this evidence has challenged our current assumptions. The evidence is especially compelling concerning locomotion. The purpose of this perspective article is to summarize the evidence supporting an impending paradigm shift from compensation for deficits to rehabilitation as an agent for walking recovery. A physiologically based approach for the rehabilitation of walking has developed, translating evidence for activity-dependent neuroplasticity after spinal cord injury and the neurobiological control of walking. Advanced by partnerships among neuroscientists, clinicians, and researchers, critical rehabilitation concepts are emerging for activity-based therapy to improve walking recovery, with promising clinical findings.

Locomotor Training Restores Walking in a Nonambulatory Child With Chronic, Severe, Incomplete Cervical Spinal Cord Injury

Background and Purpose: Locomotor training (LT) enhances walking in adult experimental animals and humans with mild-to-moderate spinal cord injuries (SCIs). The animal literature suggests that the effects of LT may be greater on an immature nervous system than on a mature nervous system. The purpose of this study was to evaluate the effects of LT in a child with chronic, incomplete SCI. Subject: The subject was a nonambulatory 4½-year-old boy with an American Spinal Injury Association Impairment Scale (AIS) C Lower Extremity Motor Score (LEMS) of 4/50 who was deemed permanently wheelchair-dependent and was enrolled in an LT program 16 months after a severe cervical SCI. Methods: A pretest-posttest design was used in the study. Over 16 weeks, the child received 76 LT sessions using both treadmill and over-ground settings in which graded sensory cues were provided. The outcome measures were ASIA Impairment Scale score, gait speed, walking independence, and number of steps. Result: One month into LT, voluntary stepping began, and the child progressed from having no ability to use his legs to community ambulation with a rolling walker. By the end of LT, his walking independence score had increased from 0 to 13/20, despite no change in LEMS. The childs final self-selected gait speed was 0.29 m/s, with an average of 2,488 community-based steps per day and a maximum speed of 0.48 m/s. He then attended kindergarten using a walker full-time. Discussion and Conclusion: A simple, context-dependent stepping pattern sufficient for community ambulation was recovered in the absence of substantial voluntary isolated lower-extremity movement in a child with chronic, severe SCI. These novel data suggest that some children with severe, incomplete SCI may recover community ambulation after undergoing LT and that the LEMS cannot identify this subpopulation.

Ongoing Walking Recovery 2 Years After Locomotor Training in a Child With Severe Incomplete Spinal Cord Injury

Background and Purpose The authors previously reported on walking recovery in a nonambulatory child with chronic, severe, incomplete cervical spinal cord injury (SCI) after 76 sessions of locomotor training (LT). Although clinical measures did not predict his recovery, reciprocal patterned leg movements developed, affording recovery of independent walking with a reverse rolling walker. The long-term functional limitations and secondary complications often associated with pediatric-onset SCI necessitate continued follow-up of children with SCI. Therefore, the purpose of this case report is to describe this childs walking function and musculoskeletal growth and development during the 2 years since his participation in an LT program and subsequent walking recovery. Case Description Following LT, the child attended elementary school as a full-time ambulator. He was evaluated 1 month (baseline), 1 year, and 2 years after LT. Examination of walking function included measures of walking independence, gait speed and spatiotemporal parameters, gait kinematics, and daily step activity. Growth and development were assessed by tracking his height, weight, incidence of musculoskeletal complications, and gross motor task performance. Outcomes Over the 2 years, the child continued to ambulate independently with a reverse rolling walker, increasing his fastest gait speed. Spatiotemporal and kinematic features of his walking improved, and daily step activity increased. Height and weight remained on their preinjury trajectory and within age-appropriate norms. The child experienced only minor musculoskeletal complications. Additionally, he gained the ability to use reciprocal patterned leg movements during locomotor tasks such as assisted stair climbing and independent tricycle pedaling. Conclusions Two years after recovery of walking, this child with incomplete SCI had maintained and improved his walking function and experienced age-appropriate growth and development.

Stepping with an ankle foot orthosis re-examined: A mechanical perspective for clinical decision making

BACKGROUND Ankle foot orthoses are used to stabilize the ankle joint and aid toe clearance during stepping in persons after incomplete spinal cord injury. However, little is known about kinematics and kinetics of stepping with an orthosis during the transition from stance-to-swing and swing-to-stance. We intended to examine if an ankle foot orthosis impeded or facilitated optimal ankle, knee and hip joint kinematics, kinetics and spatiotemporal parameters during the transition phases of normal walking. METHODS Fourteen healthy participants walked on a split-belt instrumented treadmill with and without a posterior leaf spring ankle foot orthosis at 1.2m/s. Three dimensional motion data and ground reaction forces were captured during 30-second trials of steady state walking. FINDINGS During stance-to-swing, the orthosis significantly decreased hip extension [8.6 (5.5) to 6.7 (5.5) degrees, P=0.001], ankle plantarflexion [19.4 (5.7) to 12.0 (5.2) degrees, P<0.001] and plantarflexor power [0.18 (0.03) to 0.15 (0.03) watts/body weight, P<0.001]. During swing-to-stance, the orthosis significantly increased hip flexion [32.7 (4.7) to 35.6 (5.1) degrees, P=0.028] and ankle plantarflexion [8.4 (3.5) to 10.9 (4.7) degrees, P<0.001] and decreased loading rate [0.06 (0.01) to 0.05 (0.01) N/kg, P=0.018] and braking force [0.16 (0.02) to 0.15 (0.02) N/kg, P=0.013]. Double limb support time increased significantly with the orthosis [0.19 (0.02) to 0.22 (0.03) seconds, P<0.000]. INTERPRETATION An ankle foot orthosis affected joint kinematics and kinetics during the transition from stance-to-swing and vice-versa. The use of orthosis to improve transition phase kinematics and kinetics in individuals with incomplete spinal cord injury warrants assessment.

Beyond gait speed: a case report of a multidimensional approach to locomotor rehabilitation outcomes in incomplete spinal cord injury.

Background: The efficacy of locomotor rehabilitation studies has largely been based on clinical measures of gait speed and walking performance. Although critical, gait speed does not fully capture the multidimensional benefits associated with walking recovery. The International Classification of Function, Disability and Health (ICF) model of rehabilitation emphasizes the role of personal and environmental factors in affecting quality of life and personal health status and advocates a broad approach in the assessment and treatment of people with disabling conditions. Objective: The purpose of this case report is to describe a multidimensional approach to outcome measurement reflecting the ICF model. Subject: The participant was a 59-year-old man with C7 American Spinal Injury Association impairment D tetraplegia, 16 months after injury. Intervention: The participant completed a 45-session, five days per week locomotor training program. Comprehensive evaluations were completed pre- and post-training targeting all elements of the ICF model. Outcomes: The participant achieved negligible increases in gait speed, but increased self-elected walking activity from 26 steps per day to 1273 steps per day. His assistive device changed from a platform to a rolling walker, representing a Walking Index for Spinal Cord Injury (WISCI) increase from 8/20 to 13/20. Qualitative interviews illustrated an attitudinal shift, leading to improved motivation, confidence, self-esteem, problem-solving, and increased activities/participation in the community. Ultimately, the participant was able to transition from nursing home placement to living independently. Conclusions: This case report emphasizes the need to move beyond traditional models for evaluation at the impairment and clinical level to examine the effects of interventions on independence, community integration, and quality of life.

Minimal detectable change for spatial and temporal measurements of gait after incomplete spinal cord injury.

BACKGROUND AND PURPOSE Gait deviations in individuals after incomplete spinal cord injury (ISCI) that are quantified using spatiotemporal (ST) parameters are often targeted during therapeutic interventions. The purpose of our study was to establish reliability and responsiveness of ST parameters of gait after ISCI using an instrumented walkway (GaitMat II). METHODS Sixteen individuals with ISCI participated in the study. Each subject completed at least 2 walking trials at self-selected (SS) walking speed. Intraclass correlation coefficients model 2, 1 (ICC2,1) with 95% confidence intervals (CIs), standard error of measurement (SEM), SEM percent change (SEM%), the minimal detectable change (MDC), and the MDC percent change (MDC%) were determined for 8 ST parameters including step length, single limb support, and double limb support time for the more and less impaired limb, cadence, and speed. RESULTS Excellent test-retest agreement (0.84-0.99) was observed in all ST parameters. SEM% ranged from 8% to 29%, while MDC% ranged from 21% (cadence) to 80% (double limb support time). MDC% values were relatively higher (5-12 MDC%) for the more versus less impaired limb. DISCUSSION SEM% results indicate that small to moderate changes were needed to indicate a real change in walking performance. Differences in MDC% values between limbs indicated that variability in parameters might be sensitive to level of motor impairment. CONCLUSION In individuals with ISCI, different gait, balance, or strength training programs can be compared and contrasted based on a quantifiable and meaningful change in the ST parameter of interest.

Phase dependent modulation of soleus H-reflex in healthy, non-injured individuals while walking with an ankle foot orthosis.

OBJECTIVE To examine the dynamic modulation of the soleus H-reflex while walking with a posterior leaf spring ankle foot orthosis (PAFO). METHODS Soleus H-reflexes were evoked on randomly chosen lower limb of fourteen healthy individuals (age range of 22-36 years, 7 women) while walking on a treadmill with and without a PAFO. In order to capture excitability across the duration of the gait cycle, H-reflexes were evoked at heel strike (HS), HS+100ms, HS+200ms, HS+300ms, HS+400ms in the stance phase and at toe-off (TO), TO+100ms, TO+200ms, TO+300ms, TO+400ms in the swing phase respectively. RESULTS H-reflex excitability was significantly higher in the form of greater slope of the rise in H-reflex amplitude across the swing phase (p=0.024) and greater mean H-reflex amplitude (p=0.014) in the swing phase of walking with a PAFO. There was no change in the slope (p=0.25) or the mean amplitude of H-reflexes (p=0.22) in the stance phase of walking with a PAFO. Mean background EMG activity between the two walking conditions was not significantly different for both the tibialis anterior (p=0.69) and soleus muscles (p=0.59). CONCLUSION PAFO increased reflex excitability in the swing phase of walking in healthy individuals. Altered sensory input originating from joint, muscle and cutaneous receptors may be the underlying mechanism for greater reflex excitability. The neurophysiological effect of PAFOs on reflex modulation during walking needs to be tested in persons with neurological injury. The relationship between the sensory input and the reflex output during walking may assist in determining if there exists a neurological disadvantage of using a compensatory device such as a PAFO.