Thanks in part to neuroscience researchers in the College of Medicine at the University of Arkansas for Medical Sciences in Little Rock, a 43-year-old Arizona man is walking again after about a four-year struggle to regain mobility in his legs. (Spinal Cord, Feb-2002)
University of Arkansas for Medical Sciences
Thanks in part to neuroscience researchers in the College of Medicine at the University of Arkansas for Medical Sciences (UAMS) in Little Rock, a 43-year-old Arizona man is walking again after about a four-year struggle to regain mobility in his legs. He suffered an incomplete spinal cord injury, became quadriplegic and wheelchair-dependent, and could stand but not walk.
With the benefit of two forms of physical therapy -- Partial Weight Bearing Therapy (PWBT) and Epidural Spinal Cord Stimulation (ESCS) -- the patient is now able to walk up to 1,000 feet with the aid of only a walker. The results of this first clinical trial of its kind will be published this month [February, 2002] in the neuroscience journal, "Spinal Cord" and will be featured in a documentary TV program for the Discovery Channel later this year.
The patient's ability to walk again is directly related to pioneering research performed by Edgar Garcia-Rill, Ph.D., and Robert Skinner, Ph.D., in the Department of Anatomy and Neurobiology of the college in the late 1980s. This initial work received a U.S. patent in 1991 for a "Method and Device for Inducing Locomotion by Electrical Stimulation of the Spinal Cord" (U.S. Patent #5,002,053).
These researchers found that long duration (0.2 msec to 2 msec) pulses delivered at low frequencies (0.5/sec to 10/sec) to the surface of the spinal cord could induce walking movements in the legs even after a complete lesion of the spinal cord. The authors suggested that such stimulation "has the potential for serving as a valuable adjunct to post spinal cord injury treadmill training and other therapeutic interventions" (Iwahara et al, Brain Res. Bull. 28, 99-105, 1992).
Today, that suggestion has come true, thanks to Richard Herman, M.D., at Good Samaritan Medical Center in Phoenix, AZ. For the past five years, Dr. Herman has been planning, with advice Drs. Garcia-Rill and Skinner, the first surgical implantation of stimulating electrodes in a Spinal Cord Injured (SCI) patient for the purpose of assisting locomotion. Dr. Herman secured approval from his University Hospital and the FDA to begin a multi-pronged therapy program. PWBT consists of a device that supports the weight of the body while the legs are brought into contact with a moving treadmill. This helps the patient re-learn how to walk, although some motor function in the legs is required. This form of training allowed the patient to walk slowly but with poor endurance.
When Herman combined PWBT and ECSC, there was an immediate improvement in the speed, duration and endurance of walking. ESCS reduced the oxygen (energy) cost of walking by eight times and decreased the sense of effort for walking by three times. After four months of training, the patient could perform community and homebound walking for up to 1,000 feet with only moderate fatigue. Herman established that long-duration pulses were absolutely critical, but he did not test low frequencies of stimulation. Instead, he used higher frequencies (20/sec to 60/sec), and these were not crucial in helping the patient walk.
Garcia-Rill believes that such "low-tech" approaches to SCI, as he refers to these methods, are more likely to help patients now. The "High-tech" approaches involve controversial issues and unwanted effects. For example, using fetal spinal cord grafts creates ethical problems and may involve tissue rejection because of tissue incompatibility between donor and host. Also, using stem cells -- which scientists have already found can produce tumors -- will require additional research to resolve that problem.
Instead, intensive physical therapy in the form of PWBT and ESCS are more likely to bring immediate benefits for SCI patients. When combined with exercise training, Skinner and Garcia-Rill have found that this approach decreases hyperreflexia, which is thought to lead to spasticity. However, such intensive approaches require immense dedication on the part of the patient and investment in expensive devices.
According to Garcia-Rill, "Arkansas already has one of the most progressive Spinal Cord Commissions in the country," he said, "and their collaborative efforts could help create a positive environment for future progress." He hopes that this approach to therapy could become an emerging focal point of neuroscience and neurosurgery at UAMS.
T. Glenn Pait, M.D., a neurosurgeon
and leader in spinal cord surgery at UAMS, agrees. "This technology could
be developed in Arkansas for the benefit of those who have suffered loss
of locomotion because of a spinal cord injury," he said.
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