The New Alternatives

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July 2003

By Renee Diiulio

Over the past decade, there have been huge advancements in the treatment of patients with spinal cord injury (SCI). While few people have been able to abandon wheelchairs altogether, some patients have been able to walk away from them, at least temporarily.

Unfortunately, in its current stages, the newer possible treatments are expensive, requiring high-end technology that currently is not adequately covered by insurance. More than one practitioner has wondered how new forms of back injury rehabilitation will be paid for, and it is a question that will need to be answered before this kind of treatment is employed on a massive scale.

While the insurance world works to make that happen, however, back injury rehabilitation research continues at a rapid pace. And though some practitioners are focusing on a cure for SCI-related problems, many others are doing their best to work with what they have in their arsenals right now.

the treatment and the cure

W. Dalton Dietrich, PhD

“There has never been a more exciting time in terms of what we are learning about spinal cord injury with discoveries every day on human therapies,” says W. Dalton Dietrich, PhD, professor of neurological surgery, neurology, cell biology, and anatomy at the University of Miami, and scientific director with The Miami Project to Cure Paralysis. He cites four primary areas for development: neuroprotection, transplantation, rehabilitation, and quality of life. “Next year, we’ll have 11,000 more patients with spinal cord injury. If we could treat these patients immediately after injury, we might be able to limit damage and enhance recovery,” says Dietrich.

There are a variety of drugs being explored to meet this goal, including those that target inflammation and those that prevent apoptosis (cell death). Hypothermia is another potential treatment, used to slow down injury mechanisms. According to Dietrich, however, the most exciting work being done is in effecting repair. Researchers are looking at ways to inject cells and build bridges to wake neurons and activate growth. “We want to create a permissive state for regeneration, whether that comes from building bridges between axons or utilizing cell therapy,” says Dietrich. Cell therapy researchers are working with cells that release growth-promoting factors, as well as stem cells, which have the potential to grow into the wanted cells.

“What molecules enhance growth? What factors stop axon growth? If we have axons growing into normal tissue, does it improve rehabilitation?” asks Dietrich.

These questions will take time to answer. Meanwhile, research in rehabilitation and other areas is valuable, and will be needed once a cure is found. “Once we have found a treatment for paralysis, patients will still need to undergo rehabilitation, and the methods being perfected now will be ready for use,” says Dietrich.

staying in the now
Edgar Garcia-Rill, PhD, of the Department of Anatomy and Neurobiology at the University of Arkansas for Medical Sciences (UAMS) College of Medicine, Little Rock, is not quite as optimistic regarding a cure. “Regeneration is a long way off, and do you really want to regenerate these cells if the result will not be as planned?” he asks, noting that pain fibers have been found to be the first to regenerate. “You can wait around to see if you can use regeneration or implants, or you can do something about it now,” he says.

Garcia-Rill is going for the now, looking at ways to stimulate the spinal cord with electricity and rehabilitation. His work builds on research he first published in 1984.

“In the mid ’60s, we found that there is pattern generation in the spinal cord of mammals, and motion could be stimulated by mimicking these patterns. We also knew that locomotion could be spurred with stimulation of various regions in the brain stem,” says Garcia-Rill. “So we reasoned that with spinal cord injuries, the patterns are depressed because the input from the cortex is gone. Based on the method of walking in patients first starting rehabilitation, we figured the system regressed to a neonatal pattern; rehabilitation eventually restored the normal heel-strike walking pattern. By electrically stimulating the neonatal pattern in a rat model, we were able to effect mobility.”

With this success, the research began to hone in on which segments were the critical regions and what types of stimuli worked best. “We found five segments to be critical: L1, L2, L3, L4, and L5. We also found that long pulses in a rhythmic pattern with low frequency worked best in getting the animals to walk,” recalls Garcia-Rill. “At this point, we were ready to try the system in a human patient.”

inching toward the future
Garcia-Rill joined forces with Richard Herman, MD, director of Clinical Neurobiology and Bioengineering Research Laboratories at the Good Samaritan Regional Medical Center, Phoenix, where the research takes place. Herman is also a research professor of bioengineering and exercise science at Arizona State University. He describes the research as “a new strategy for training wheelchair-dependent patients with damage to their spinal cord from the lower neck region to the lower back region.”

With FDA approval for three patients, the criteria for his first two were that they displayed a little bit of sensation and involuntary muscle control, and had experienced unsuccessful rehabilitation. “We did not anticipate the level of success we achieved,” says Herman.

Typically, SCI patients are treated with partial weight-bearing therapy, where they are placed on a treadmill, and a harness supports 30% to 40% of their weight. Physical therapists work with them to promote a well-organized gait pattern, a process that can take up to 4 months. “Those individuals who learn to walk will travel over a standard 50-foot walkway in 3 to 4 minutes, at the end of which they are exhausted,” says Herman. “Compare this to a healthy individual, who will complete the distance in roughly 12 to 13 seconds.”

His research patients managed to cover the distance in 60 seconds, a 75% reduction in time, and were able to do so with 50% less effort. How? Through the use of electrical stimulation.

An electrical device was implanted on the back of the spinal cord below the level of the damage on both sides of the midline. This device was connected by a wire to a receiver placed on the skin of the abdominal wall. An antenna was then attached to a remote device outside the body that controlled the frequency, duration, and intensity of the current applied by the implanted electrical device.

After the implantation surgery, the patients were retrained with partial weight bearing and then let loose on the 50-foot walkway. “Within 2 weeks of healing from the implantation process, we noticed an improvement in their walking,” says Herman. “They maintained a well-organized gait but were able to walk faster and further than before.” In addition, Garcia-Rill notes that the patients used 6% to 8% less oxygen while on the treadmill.

“We don’t yet know if we can skip the partial weight-bearing technique. The treadmill enhances information and gives the centers controlling locomotion a chance to adopt the new gait pattern,” says Herman. “But we determined that the device changed the way muscle energy was used. Before stimulation, the muscle used carbohydrates as fuel, but afterwards, the muscle used fat. The switch helped the patients’ endurance and is now considered the number one thing the nervous system needs to do,” says Herman.

While he searches for a third patient, the first two are living in the community. “Neither is free of the wheelchair—it is still their primary mobility source—but they have regained some function and can get up to walk to the table or the bathroom. The second patient has even been able to maneuver stairs,” Herman says. “At the moment, this is just an experiment. Once we’ve completed research on the third patient, we can consider its widespread applications, as well as ways to reduce cost. The equipment and training are very expensive for the general population, but we may be able to reduce costs by half,” he adds.

finding the tools

Edelle Field-Fote, PT, PhD

Cost is an important factor to consider, agrees Edelle Field-Fote, PT, PhD, associate professor in the division of physical therapy at the University of Miami School of Medicine. But it should not be a prohibitive factor. “Rehabilitation will never be a cure, but it can make a significant impact without being invasive,” she says. She is working to evaluate physical therapy interventions to determine which are the best for promoting locomotion, as part of the research under way at The Miami Project to Cure Paralysis.

Dietrich notes that an entire floor is devoted to rehabilitation there. “Training has been shown to increase a patient’s quality of life, decrease the risk of heart disease, and decrease lipids in the blood. We want to quantitate the results and determine what factors affect them,” he says. “One day we will combine locomotion training with drug or transplantation treatments to induce function.”

Rehabilitation’s value is not in doubt, and Field-Fote’s research is funded by a 5-year grant from the National Institutes of Health. She is currently evaluating five methods of rehabilitation, all of which incorporate bodyweight support and locomotor practice.

“Massed practice or massive practice incorporates the concept of constrained induced therapy. In working with stroke patients, it was determined that if you constrained the good arm and made them use their most affected arm repeatedly, they recovered better,” she says. The practice can be applied to SCI patients as well.

“The first method we are exploring is traditional treadmill training, where we use a harness to lift the patient’s weight and the therapist helps to move the legs,” Field-Fote explains. A method frequently used in clinics today, it has both advantages and disadvantages. “The problem with this method of treatment is that it is hard work for the therapist and is inconsistent from step to step. The advantage is that the therapist can give just the amount of assistance required by the patient,” says Field-Fote.

The second method, which involves flex or reflex stimulation, is unable to be customized to individual need, but has been shown through research to strengthen normal walking circuitry. Here, the patient’s weight is supported by a harness while on the treadmill; the patient receives stimulation at a point on the leg that causes him or her to pick the leg up off the ground. “By electrically stimulating the leg at the appropriate point in walking, we can cause movement,” says Field-Fote.

The third method, the lokomat, has received a lot of press; the lokomat is a robot that walks on the treadmill with the patient strapped in and incorporates body-weight support. “This method is very consistent step to step, but the patient could potentially relax, do nothing, and still walk,” Field-Fote says.

The fourth method moves away from the treadmill to an 80-foot track, above which is a trolley with the body weight-supporting harness. “Here, the therapist is unable to control the patient’s speed, but the patient trains in the environment in which they’ll be walking,” she says. “This is beneficial as the mechanics of walking over ground differ from those used walking on a treadmill.”

The fifth method is geared toward patients with upper extremity immobility and employs massed practice for 2 hours every day as well as electrical stimulation.

“It is too early yet to say which method works best. All have shown improvement, but we have not studied enough subjects to make any determinations,” says Field-Fote.

It is likely though that the best results may be mitigated by the most economical. “Not a lot of clinics have weight-bearing capabilities, and bilateral lower extremity involvement requires a lot of man-hours. It may take three people to train one patient, whereas the robot will require only one trainer and will be less physically demanding of the therapist,” Field-Fote says.

“It’s important to understand the best types of intervention and rehabilitation so we will be ready when there is a cure for spinal cord injury,” she adds. “Patients won’t just jump off the operating table and walk.”

Renee Diiulio is a contributing writer for Rehab Management.

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July 2003