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Invited Commentary

VR Edgerton, PhD, is Professor and Vice Chair, Department of Physiological Science, and Professor in the Department of Neurobiology, University of California, Los Angeles, CA 90095

There are several very important points that should be noted from the article by Behrman and colleagues¹ addressing the issue of the potential to regain some locomotor function following a severe spinal cord injury in a young child.

1. As has been demonstrated and implicated previously, the clinical motor scores that are classically derived are nearly irrelevant in defining the level of function attributable to the spinal circuitry in generating stepping.² As has been shown in adults, individuals with a spinal cord injury that is severe, but categorized as incomplete, can utilize the remaining supraspinal influence to take advantage of this capacity of the spinal circuitry to take care of many of the details necessary to execute standing and stepping if this circuitry has not been allowed to "learn" to become nonfunctional.
   
2. The plasticity of the neuromuscular system following a severe spinal cord injury can persist for months or even years. It is likely that the more prolonged the period between injury and the locomotor training, the more obstacles will have to be overcome because of the secondary deficiencies (eg, loss of muscle mass, weakening of connective tissue, bone demineralization, orthostatic intolerance) associated with continuous lack of function, particularly absence of load bearing. Nevertheless, considerable plasticity persists for years.
   
3. It must be accepted that to achieve a significant level of recovery, the number of training sessions needed far exceed those that are normally available to patients. Furthermore, the pattern of improvement in locomotor function over the course of weeks and months of training occurs not as a slow continuous progression, but incrementally. Plateaus can be reached in the training process with no apparent improvement, and suddenly significant improvement occurs. This seems reasonable given the basic biology of locomotion, whereby a certain level of functional potential in a given component of the neuromuscular system must be achieved in order to execute a more complicated and challenging component of stepping.
   
4. Behrman and colleagues are to be commended for quantifying the number of steps executed throughout the day by the subject. This is important because it gives a measure of how the physiologically improved function is manifested in the individual's daily life. It also is important because of the phenomenon reported by Wernig and colleagues³ that, in a 5-year follow-up of patients who initially had been trained to step following a severe spinal cord injury, almost all of the patients had at least maintained the level of function achieved at the completion of the therapy and a number of them continued to improve. The important point here is that, once a critical level of function in standing and stepping is reached, these activities become part of the individual's daily routine and, in effect, he or she continues the task-specific training.
   
5. The economic impact of this type of outcome is enormous. The annual cost of health maintenance of people who are paraplegic within the first year of injury was estimated in 2006 to be $270,913, and $27,568 for each succeeding year.⁴ With a normal life expectancy for this individual case, medical costs currently would be almost $2 million. If the subject had remained unable to stand and step, all indications are that the medical costs would greatly exceed this estimate. When you consider the cost of medical care for the duration of the spinal cord injury trial, it is almost certain that a few months to a year of training is a very good investment in terms of economic consequences alone. However, this might be considered trivial when considering the immeasurable impact for the life span on the expanded lifestyle available.
   
6. The observations reported in this article challenge patients, their family, and their support team, as well as the tending physician, as to whether the lack of locomotor function in individuals with a severe but incomplete lesion is due to their impaired neuromuscular system and being unable to step or stand, or to not being given the opportunity to experience and practice load-bearing functions in a manner that would facilitate recovery.
   

Clearly, one cannot assume that these results can be generalized to all children with such a severe injury, but they do demonstrate clearly what can happen with the appropriate intervention. In another recent case of locomotor training in a child, a similar dramatic improvement in function was gained.⁵ At the same time, it cannot be concluded from these case studies that the level of improvement was a function of age. Almost all evidence related to recovery from experimental injuries at different ages in laboratory studies, however, is consistent with this concept. How many individuals with a severe but incomplete spinal cord injury are wheelchair-dependent but need not be? With the continuing success of data collection under well-controlled conditions across multiple clinical sites within the Neural Recovery Network sponsored by the Christopher and Dana Reeve Foundation⁵ and similar clinical efforts, it should be possible in the future to predict with improved accuracy the level of improved function that can be expected, as a result of receiving a known amount and kind of activity-based therapy, for a given individual at a given age having a spinal lesion that is assessed functionally and quantitatively.

	References

 

1. Behrman AL, Nair P, Bowden M, et al. Locomotor training restores walking in a nonambulatory child with chronic, severe, incomplete cervical spinal cord injury. Phys Ther. 2008;88:580–590.[Abstract/Free Full Text]
2. Maegele M, Müller S, Wernig A, et al. Recruitment of spinal motor pools during voluntary movements versus stepping after human spinal cord injury. J Neurotrauma. 2002;19:1217–1229.[CrossRef][Web of Science][Medline]
3. Wernig A, Nanassy A, Müller S. Laufband (treadmill) therapy in incomplete paraplegia and tetraplegia. J Neurotrauma. 1999;16:719–726.[Web of Science][Medline]
4. Spinal Cord Injury Information Network. Available at: http://www.spinalcord.uab.edu/show.asp?durki=21446.
5. Funds raised are earmarked for Christopher and Dana Reeve Foundation and Frazier Rehab Institute Research. Available at: http://www.christopherreeve.org/site/c.geIMLPOpGjF/b.1038451/apps/s/content.asp?ct=5051295.

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This Article Full Text (PDF) Submit a response Alert me when this article is cited Alert me when Rapid Responses are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Edgerton, V R. Search for Related Content PubMed PubMed Citation Articles by Edgerton, V R. Related Collections Gait and Locomotion Training Spinal Cord Injuries Pediatrics: Other Social Bookmarking                      What's this?