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Letters and Responses |
1.0 m/s and nearing normal values. The trial was conducted in response to a National Institutes of Health request for applications (RFA) to initiate a clinical efficacy trial of body-weight–supported ambulation training following incomplete spinal cord injury (RFA HD-98-005, National Institute of Child Health and Human Development).3 Several questions can be raised from a clinician's viewpoint when considering translating this knowledge to practice, including: Who was in the study? What were the interventions? What was the delivery intensity? When after injury was the intervention delivered, and for how long (duration)? In other words, what decisions do we make as clinicians from the outcome of this trial, and what questions does it generate as a scientist? This response serves as a follow-up to the dialogue begun by van Hedel and offers only an introduction to a dialogue that certainly deserves a more in-depth analysis.
The recent RCT in SCI2 studied people within 8 weeks of traumatic SCI and admitted for rehabilitation at 6 partnering clinical sites: Magee Rehabilitation Hospital (Philadelphia, Pa), Shepherd Center (Atlanta, Ga), Ohio State University (Columbus, Ohio), Rancho Los Amigos Rehabilitation Hospital (Los Angeles, Calif), McGill University/ Institut de Readaptation de Montreal (Montreal, Quebec, Canada), and University of Ottawa Rehabilitation Hospital (Ottawa, Ontario, Canada).1,2 All participants received usual rehabilitation care plus 1 of 2 locomotor interventions 5 times per week for 12 weeks. As van Hedel comments, 1 of the interventions—locomotor training (LT)—is a physiologically based intervention supported by a vast literature in basic science of the neurobiology of walking and activity-based plasticity in animal models and some human evidence providing the theoretical background. The other comparison intervention comprised the conventional arm of the study, with subjects receiving mobility training for standing and walking over ground using supplemental equipment to accomplish the activity (eg, assistive devices, standing frames, parallel bars), comparable to current practice.
Although "over-ground training" may appear to be common to both interventions, the over-ground training provided in each study arm differed substantially in their theoretical underpinnings and subsequent execution and process of delivery. The LT protocol provided for intense practice of stepping in the body-weight support and treadmill environment followed by an immediate translation of skills to an over-ground environment. The intent of LT was to provide a task-specific sensorimotor experience to generate a stepping response. The goal of step training on the treadmill was primarily development of the capacity to step. Daily over-ground training immediately followed step training on the treadmill and included an assessment of transfer of the skills acquired on the treadmill to an over-ground environment (eg, step initiation, stepping, stopping, balance). The over-ground training also prepared the individual for home and community ambulation (eg, introduction of assistive devices, negotiating uneven terrain, varying walking speed). Loco-motor training on the treadmill and then over ground was conducted following specific guidelines for maximizing weight bearing of the lower extremities, minimizing loading of the arms, mirroring the kinematics of walking (eg, upright posture, joint positions, arm swing, speed), and minimizing use of compensatory movements to walk.1,2,4
In comparison, training for the control group occurred only over ground and was consistent with usual care for gait rehabilitation following SCI. Thus, load bearing was initiated using a variety of equipment: tilt table, standing frame, or parallel bars with or without bracing, if needed. If gait training continued over ground, bracing and/or an assistive device were provided initially to afford support and compensate for weakness, balance deficits, and uncoordinated movement patterns. Training targeted weight bearing, improving the gait pattern, and balance. Changes in assistive device or bracing were part of progression. The control group matched the experimental intervention for a minimum of a half hour of weight bearing per day; this element was required to equate the intensity of training across groups. The control intervention did not include any treadmill-based training.
Van Hedel refers to the over-ground control training as "task-oriented" training and contrasts it to the LT intervention using body-weight support and the treadmill. Both interventions may be "task-oriented" in that both addressed walking, but each was executed quite differently. Certainly, the approaches were not impairment-based strategies (eg, strength training, endurance training, or spasticity-reducing methods5), but both afforded weight-bearing and walking practice.
Van Hedel points to the surprising outcomes of this study for people with an ASIA C classification of impairment and the high percentage of people who benefited (92%) relative to past reports of 40% achieving independent ambulation, defined as a Functional Independence Measure (FIM) Locomotor score of 
5.1 Subjects with ASIA C classification walked an average of 1.0 m/s at 6 months following injury regardless of the intervention and achieved an FIM Locomotor score of 5. This is an overwhelmingly positive and remarkable outcome.
One interpretation and clinical response may be that early, intense intervention targeting weight-bearing and walking practice is beneficial after SCI for recovery of walking, in particular for the ASIA C population. Comparisons of walking outcomes from recent databases from National Institute of Disability and Rehabilitation Research (NIDRR) Model SCI Centers, the VA SCI Medical Center Network, or the NeuroRecovery Network (Reeve Foundation) may provide a useful comparison of a comparable cohort for walking recovery and the current standard of care. A more in-depth analysis and description of the current rehabilitation practice for gait training after SCI would be helpful in identifying the critical elements of the conventional over-ground mobility training and progression that may have contributed to the RCT outcomes. The clinical response to the interventions as measured by the FIM and gait speed provides valuable information for efficacy and functional gains. Knowledge of the process of recovery and mechanisms of response to the interventions, however, would be advantageous from a scientific and clinical decision-making perspective.
In this trial, the safety and feasibility of providing this intervention in the acute SCI population was established with no differences reported in adverse reactions across study groups.2 This result may be advantageous in designing and executing future studies advancing multiple or combined therapeutic strategies. Furthermore, a greater-than-expected attrition rate from randomization to 6-month follow-up accounted for a substantial reduction in the upper motor neuron study population from ASIA C (n=52) and D(n=7) to ASIA C (n=38) and D (n=7) (see Fig. 1 in Dobkin et al2), although withdrawal rates were reportedly similar across the 2 groups.
Two populations that did not benefit stand out from these findings. First, people with an SCI impairment classification of ASIA B did not demonstrate improved walking outcomes from LT or conventional over-ground training. This population may require combined or augmented therapies (ie, pharmacology, electrical stimulation) to improve outcomes for walking recovery. Second, 8% of the ASIA C population did not achieve independent walking and community walking speeds. The reasons contributing to the differential outcomes would be of interest in categorizing "responders" and "nonresponders," in modifying the intervention, or understanding other factors. People who did not show significant improvement at 6 months may be candidates for alternative approaches or, again, combined therapies.
This RCT was a first for examining an alternative physical intervention, a physiologically based intervention, targeting walking recovery in the acute SCI population. From that perspective, the trial is historical for SCI rehabilitation and an important event for clinicians and people with SCI, with strong evidence for early mobility and walking practice for people with ASIA C impairments. Evidence-based practice is a dynamic process mirroring both the evolution of science and the requisite translation to clinical practice. Findings of clinical trials likely provide the science and yet stimulate controversy and generate many more questions as translation into practice is considered. An example is an RCT that examined the use of methylprednisolone acutely after SCI to enhance motor recovery. Outcomes from that RCT continue to drive ongoing debate as to the clinical use and benefit of and scientific inquiry related to methlyprednisolone.6–12
Planning and conducting a clinical trial in SCI is a daunting process that continues to spawn discussion in scientific and rehabilitation communities delineating guidelines and criteria for executing a successful RCT and translation of findings to practice.13–15 With this backdrop, dialogue examining this RCT in SCI for the recovery of walking, the outcomes, and its relevance within a continuum of scientific findings is necessary and productive in advancing the science of rehabilitation for people after SCI.
Associate Professor
University of Florida
Research Scientist
VA Brain Rehabilitation Research Center-
Gainesville, Fla
References
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