Challenging the Nervous System Can Optimize Function After Spinal Cord Injury
Practice, training and skilled activities are fundamental when the goal is to reactivate, rewire and restore.
By Edelle Field-Fote, PT, PhD, FAPTA
Director of SCI Research and Co-Project Director, Shepherd Center SCIMS Program
In the 30-plus years since I was a young physical therapist, there has been a revolution in what we know about the nervous system, as well as in our understanding of the process of neural recovery and functional restoration after injury. Until the 1980s, researchers and clinicians believed the human nervous system had a limited capacity to recover from injury. They thought the best approach to recovering from spinal cord injury was a long period of rest; and once training was initiated, it focused exclusively on compensating for lost function.
How times have changed. What we now know is that the nervous system is plastic, meaning it responds to challenges, adapts and rewires based on the movement activities of the individual. We have also learned that, depending on the area and extent of injury, many people can experience the restoration of certain functions even years after injury.
We had early hints about the importance of activity and practice from research related to the growth and development of the nervous system. In the 1960s, researchers found that if animals are deprived of normal experiences during the critical periods of nervous system development, they never develop the capacity for normal function in that system. Given the recent announcements of the 2015 Nobel Prizes, it is interesting to reflect back on the 1981 Nobel Prize in Medicine, which went to David Hubel and Torsten Wiesel. In their studies, they found that if a mask was put over the eye of a kitten during the period when the visual system was developing, the kitten never developed the ability to see through the masked eye. Even though all the necessary nervous system structures were in place, because the animal was deprived of visual activity in the masked eye, the necessary interconnections between these structures never developed. These studies demonstrated that experiences that activate the nervous system are essential to the development of normal wiring in the nervous system.
While the aforementioned example of the visual system in young animals illustrates the processes that go on during development of the nervous system, there is good evidence that after trauma the nervous system is again highly plastic and goes through a period of rewiring. Just as with normal development, the nervous system is especially receptive to the influences of activity, practice and training during this rewiring period. These experiences are essential for functional restoration of movement and muscle control following injury.
More frequently, in the basic science research related to spinal cord injury (SCI), researchers who are working with animal models of SCI are using enriched environments with ladders, ropes, wheels and toys of various types to provide as many opportunities as possible for the animals to grasp, run, climb and practice moving. Research shows that animals housed in enriched environments have greater improvement than their counterparts in standard housing who do not have the opportunities to practice movement.
So does this mean that it is only possible to take advantage of the plasticity of the nervous system in the early period after injury? Not at all. In fact, early after injury factors like edema, or swelling, in the spinal cord can limit the ability of the nervous system to rewire. As the edema resolves, the nervous system becomes more responsive to practice and training. That means, depending on the injury, there may be potential to improve function long after the time of discharge from the rehabilitation hospital.
Practice, training and skilled activities like we use at Shepherd Center are essential elements for functional restoration. Our therapy programs are the forces that activate the nervous system and promote the reactivation and rewiring that are the foundations of improved function. And our SCI research program intentionally focuses on identifying the most effective practice and training interventions. A recent scientific article review of the experimental treatments available for persons with spinal cord injury found that the studies that have the largest, most beneficial effects do not involve expensive technologies or invasive surgeries, but in fact, the studies that have shown the largest effects on function after spinal cord injury are studies that involve practice and training (see Gomes-Osman et al 2015).
In my discussions with people who have had a recent SCI, I try to emphasize that the nervous system they have at the time of discharge from the rehabilitation hospital is not the nervous system they will have a year later. For this reason, it is important to continue to try out new movement experiences that challenge the nervous system. Practice, training and skilled activities are fundamental when the goal is to reactivate, rewire and restore.
EDELLE FIELD-FOTE, PT, Ph.D., is the director of spinal cord injury research at Shepherd Center. She joined the staff in May 2014 after serving for 20 years as the director of the Neuromotor Rehabilitation Research Laboratory at the Miami Project to Cure Paralysis. Her research focuses on restoring motor function after spinal cord injury by making use of spinal pathways not damaged by injury.
Shepherd Center, located in Atlanta, Georgia, is a private, not-for-profit hospital specializing in medical treatment, research and rehabilitation for people with spinal cord injury, brain injury, multiple sclerosis, spine and chronic pain, and other neuromuscular conditions. Founded in 1975, Shepherd Center is ranked by U.S. News & World Report among the top 10 rehabilitation hospitals in the nation. In its more than four decades, Shepherd Center has grown from a six-bed rehabilitation unit to a world-renowned, 152-bed hospital that treats more than 935 inpatients, 541 day program patients and more than 7,300 outpatients each year.