Could the future of rehab include walking paraplegics, quadriplegics?
Could the future of rehab include walking paraplegics, quadriplegics?
Researchers in Arkansas may have answer
Clinicians and researchers recently showed how a quadriplegic, wheelchair-dependent man could walk 400 to 1,000 feet with only a walker for assistance.
Their recently published study sets the stage for a new area of rehabilitation that may one day enable many spinal cord injury (SCI) patients to achieve more independence and mobility in their daily lives.
The treatment that enabled one SCI patient to walk will not necessarily eliminate wheelchair dependence, but it will allow patients to do more for themselves in their homes and possibly enable them to visit restaurants or other places without their wheelchairs, says Richard Herman, MD, a research professor of bioengineering and a research professor of exercise science at Arizona State University in Phoenix. Herman also is the director of the Clinical Neurobiology and Bioengineering Research Laboratory at Good Samaritan Rehabilitation Institute in Phoenix.
Herman is a lead author of a study on an ASIA C spinal-cord-injured patient’s progress under a treatment plan that included partial weight-bearing therapy (PWBT) followed by epidural spinal cord stimulation.1
The rehab process has the potential to work for some patients who have incomplete SCIs and who are highly motivated, because it requires a great deal of physical effort and discipline, Herman says.
Of an estimated quarter-million SCI patients in this country, about half have an incomplete spinal cord injury. Of these patients, the ones who are classified as ASIA Cs or ASIA Bs, who have some movement and sensation in the lower extremities, are the most likely candidates for the program, Herman says.
This might amount to 10,000 to 12,000 SCI people, Herman says, adding that there also is a potential for the program to help patients with multiple sclerosis, cerebral palsy, and strokes.
"We’re gearing ourselves on the next experimental round to include a wider variety of patients, including spinal cord B patients and multiple sclerosis patients, and we may enter into this with cerebral palsy, but we haven’t made up our minds yet," Herman says.
It has taken four decades of SCI research to reach this breakthrough point, says Edgar Garcia-Rill, PhD, professor of anatomy and neural biology, professor of psychiatry, and director of research for the Arkansas Center for Neuroscience in the department of anatomy and neurobiology at the University of Arkansas for Medical Sciences in Little Rock.
Under a National Institutes of Health grant, Garcia-Rill helped to develop the device that stimulates the spinal cord to induce locomotion.
"Back in the 1960s, studies found that in the spinal cord there is a pre-programmed sequence of contractions needed for walking," Garcia-Rill says. "They’re spinal pattern generators, and they generate automatically the flexion-extension sequences for each limb."
By the mid-1980s, researchers began to theorize that when a person’s spinal cord is injured, it regresses to a neonatal pattern, very much like a baby or a Parkinson’s disease patient who walks on his or her toes, Garcia-Rill says.
"What we thought might happen is that in an adult spinal cord injury patient, you have a spinal cord that turns into a neonatal spinal cord," Garcia-Rill explains. "And we used a fairly complicated preparation to find out that the neonatal spinal cord requires that you stimulate it using very low-frequency, long-duration pulses."
This led to the idea of stimulating the spinal cord on the surface or back of the spinal cord at a low frequency.
The device was patented by the University of Arkansas for Medical Sciences in the early 1990s. Garcia-Rill and colleagues were ready to test it on a spinal cord injury patient in the mid-1990s, which is when they met Herman, who spent the next few years helping to bring the process to a clinical application.
"What Herman did was choose his subject very wisely," Garcia-Rill notes. "This is an individual who is highly motivated because this program is a lot of hard work and requires a lot of dedication."
Although the patient selected for the study is classified as a quadriplegic, he is capable of standing with a walker. However, the man, who is in his 40s, was unable to walk before the program, Garcia-Rill says.
Herman is working on developing a protocol for the program so it can be duplicated by others, including neurosurgeons and rehab clinicians. He offers this basic look at how the process works:
• A patient is selected based on the type and extent of injury, motivation, and other factors. Two important criteria are that the patient is capable of pushing his/her body weight up from the wheelchair, which is an indication of the patient’s upper-body strength, and the patient must be stable in the trunk so that there is a modicum of balance when the patient is upright.
• An oversight committee approves the selected patient, and the patient is told that the project may involve one to two years of commitment.
Patient builds strength before surgery
• Prior to surgery, a physical therapist works with the patient, guiding the patient during exercises involving partial-weight-bearing therapy (PWBT) and progressive training with increasing treadmill rates.
The patient is placed in a parachute-style harness that supports the patient’s weight, Garcia-Rill says. "As the patient gains strength and supports his own weight, he takes over the weight-bearing, and this is a way of building up strength," he adds.
• Once the preparation is complete, a surgeon inserts a pair of Pisces-Quadplus electrodes into the dorsal epidural space over the upper lumbar enlargement of the spinal cord, placing each electrode one to two millimeters off the mid-line.
The devices have a battery with a receiver placed under the skin, and the controller has a transmitter in which frequency and duration can be set.
"The remote device is small like a cell phone, and the whole thing can be carried in a little pouch that a person wears and puts in the pocket," Herman says.
• Once surgical healing is complete, the patient is retrained to pre-surgery PWBT levels. The patient’s gait performance is assessed by measuring average speed, stepping symmetry, sense of effort according to the Borg Scale, and physical work capacity.
• With the combination of PWBT and epidural spinal cord stimulation (ESCS) through the implanted device, the patient has smoother stepping patterns at higher treadmill rates, as well as improved endurance and speed during over-ground walking.
ESCS provides very low-level electrical stimulation that the patient experiences as a vibration. There is no pain, Garcia-Rill says.
"What is so impressive about this treatment is that they can not only walk, but have been trained to walk with PWBT and can walk with a low sense of effort," Herman says. "It’s near effortless for a period of time."
The patient’s self-reported perception that the walking is easily done is supported by data that shows the patient is metabolizing fat while exercising in the program, Herman explains.
"As you metabolize carbohydrates, your sense of effort goes up, and as the sense of effort goes up, it switches off and burns carbs," Herman says.
Investigators also observed what happened when the ESCS was turned off. They found that the patient had learned walking patterns that are active without stimulation, Herman notes.
"He can walk pretty good distances, but not as far as with the current," Herman says. "It takes him a little more effort, but it’s pretty functional."
For instance, the first patient has learned to walk within his apartment without the electrical current. It helps that his carpet is more resistant than it would be if he walked on a hard surface, Herman says.
The idea is that one day, patients with SCIs and other injuries could use this sort of device on their own, so when they need greater mobility they can have it, Herman says.
"What it does is help them do more things for themselves independently," Herman says. "He can walk around the house and have access to parts of the house that he didn’t have before, like getting into the bathroom by walking in there."
Herman’s investigations of the procedure continue with a second patient, who is a wheelchair marathon athlete and has more severe weakness due to his spinal cord injury.
"He has a neck injury, and this was a low thoracic T-8 injury," Herman says. "He doesn’t walk as beautifully as the first man does, but he does walk with a low sense of effort."
This patient’s goal is to walk part of the wheelchair marathon. "So I think we’ll allow him to do that somehow," Herman says.
Need More Information?
- Edgar Garcia-Rill, PhD, Professor of Anatomy and Neurobiology, Professor of Psychiatry, Director of Research, Arkansas Center for Neuroscience, University of Arkansas for Medical Sciences, 4301 W. Markham Ave., Slot 510, Little Rock, AR 72205. Telephone: (501) 686-5167. Fax: (501) 686-6382. E-mail: [email protected].
- Richard Herman, MD, Research Professor of Bioengineering, Research Professor of Exercise Science, Director of Clinical Neurobiology and Bioengineering Research Laboratory, Good Samaritan Rehabilitation Institute, 1012 E. Willetta St., Phoenix, AZ 85006. Telephone: (602) 239-2380.
Reference
1. Herman R, He J, D’Luzansky S, et al. Spinal cord stimulation facilitates functional walking in a chronic, incomplete spinal cord injured. Spinal Cord 2002; 40:65-68.
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