September 16, 2005|
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September 16, 2005 |
A pioneering doctor who treated Christopher Reeve says exercise may be the way to fight paralysis By Jonathan Bor It wasn't walking as most people know it. Without electrodes firing his weakened muscles, his legs would barely move. Without two therapists physically placing one foot in front of the other, he would likely stumble. And without a body sling suspended from above, he would surely fall. To McDonald, recruited earlier this year to head a spinal-cord injury program at Baltimore's Kennedy Krieger Institute, there is nothing futile about exercising limbs that can barely move on their own. The 43-year-old neurologist says his work with the late actor Christopher Reeve demonstrated that exercise might hold the key to something scientists long considered impossible - reactivating neural pathways that have been silent for years. "In this new world, the nervous system is much more capable of change than we ever thought," McDonald said in a characteristic burst of enthusiasm. "Old ideas are starting to fade away." McDonald arrived in May with a treatment team from his former base, Washington University in St. Louis. It was partly on the strength of his work there with Reeve that Kennedy Krieger hired him to elevate its spinal cord program, which lacked the national reputation of its programs in autism, cerebral palsy, lead poisoning and other neurological disorders. "We weren't pushing the frontier to make [the condition] better," said Dr. Gary Goldstein, president and chief executive officer. With the hiring of McDonald and the opening of new labs and a rehabilitation gym, Goldstein hopes Kennedy Krieger will become a major referral center for spinal cord injuries. Already, the hospital is showing signs of that, with patients coming not just from the Mid-Atlantic region but from places as far-flung as Texas and California, Greece and Colombia. Goldstein, who remembered McDonald as a bright young medical student at the University of Michigan, offered him an arsenal to enhance his efforts to get paralyzed people moving again: support for stem cell research, collaboration with neighboring Johns Hopkins and the latest imaging technology. It also promised an ideal patient profile, heavy on children whose still-developing nervous systems may stand to gain the most. "With children, you're walking in on something that's moving, not something that's static," Goldstein said. "Not that there isn't potential in adults, but if you're going to try something out, you should try it in children." Exercise is the core of McDonald's program. It is based on the theory that repetitive activity can awaken the spinal cord to grow new cells, sprout connections and direct movement independently of the brain. In the institute's new rehabilitation gym, patients are helped onto stationary bikes and hooked to electrodes that cause their leg muscles to contract. Some, like 21-year-old Robby Beckman, work out on treadmills, aided by electricity and therapists. Tall, lanky and still projecting an athlete's vigor, Beckman is what doctors call an "incomplete quad" - largely paralyzed from the neck down but capable of short, weak movements in his arms and legs. Though held in a sling, the former pitcher for Salisbury University was positioned low enough so that his legs were forced to bear some weight on their own. "You like doing that much weight bearing?" asked McDonald, standing to one side with arms crossed. "I'd like to do more," said Beckman. "Great, isn't it?" the doctor replied, smiling in approval. Pattern generator With boyish looks and irrepressible optimism, McDonald has become one of the most visible and charismatic proponents of activity-based therapy. But the idea wasn't his alone. In the 1930s, nurses tried in vain to restore movement to polio victims by forcibly moving their limbs and encouraging them to float in pools. The strategy didn't work, McDonald said, because it addressed the wrong disease. Polio destroyed neurons along the spinal cord, damage too diffuse to benefit much from exercise. In contrast, a spinal injury damages a narrow band of spinal tissue, disrupting the flow of signals from the brain to the places below the injury. Similarly, information gathered in the extremities has no way of crossing the breach to reach the brain, which is why patients lack sensation in affected areas. But what if the spinal cord had its own mini-brain that played a role in directing movement? For decades, biologists uncovered some evidence of that in a collection of cells at the base of the cord that helped control rhythmic movements such as walking and cycling. The region, called the pattern generator, was identified in locusts and lampreys as well as cats and rats. Then, in 1991, a Canadian scientist demonstrated that a cat whose spine was crushed could learn to walk again if trained, raising the possibility that forced movement retrained the pattern generator to act on its own. "If the cat is trained to walk on a treadmill, they will walk and not stand," said Dr. Edelle Field- Foote, a University of Miami neurologist. "The brain doesn't need to be involved in moment-to- moment decisions like what muscles need to be involved." Dr. Douglas Kerr, a Johns Hopkins neurologist, said the idea of retraining the pattern generator holds promise. "The truth is, walking is an inherent spinal cord reflex," said Kerr, who has begun referring patients with a paralyzing disease called transverse myelitis. "We know that exists in animals. It never intrinsically makes sense [that] it's gone in humans." Though scattered doctors, including Field-Foote, started testing repetitive exercise in their patients, McDonald said the idea came to him when he was assigned to Washington University's rehabilitation unit in the mid-1990s. There, he watched patients learning to maneuver wheelchairs and feed themselves with long, curving forks and spoons. Therapists were earnestly helping people prepare for life at home, yet something seemed amiss. "All of a sudden, it was like a light bulb went off," he said. Nobody was encouraging the patients to exercise, which everyone knew promoted a strong heart, bone density, healthy skin and muscle mass. Beyond the obvious health benefits, he thought, movement might also reactivate the pattern generator.
Reeve's example "He was the most motivated individual I ever saw," he said. "I was surprised to find that he was working his tail off to do as much as he could, but nobody was helping him. I'd say, 'Chris, I know we can help you.' " Reeve, who became McDonald's patient in 1999, worked out on a stationary bike three times a week, with wires attached to his legs and buttocks. Therapists helped him move his legs in a pool and, as his strength increased, urged him to push against the wall. Two years into the program and six years after his injury, Reeve was able to move one wrist and some of his fingers and toes. He could feel a pin prick nearly anywhere and detect degrees of hot and cold. Later, said McDonald, he could tap fingers on command - index, ring, pinky. Though Reeve never walked again, dying last year of a bloodstream infection, his was the first documented case of a complete quadriplegic regaining function so long after being injured. Dr. Oksana Volshteyn, a St. Louis neurologist who worked alongside McDonald, said he brought a sense of possibilities to the unit. "Everything in his mind is doable regardless of situation or resources," she said. "If we needed to work at night, we'd work at night." Though scientists are intrigued by Reeve's achievement, many say they don't know exactly what to make of it. "I think if the approach is ever going to be proven scientifically, you'll have to have more subjects than one," said Dr. Kris Ragnarsson, head of rehabilitation medicine at the Mount Sinai School of Medicine in New York. McDonald says he has already done that, recently completing a study that compared 30 people who received activity-based therapy with an equal number who did not. Though he declined to discuss the results before publication, which he hopes will be soon, he hinted that the results will be encouraging. In her studies of activity-based rehabilitation, Field-Foote said she documented an 80 percent improvement in patients' walking speed. But she said her patients entered therapy only partially paralyzed. Unlike Reeve, some could wiggle their toes or move one leg better than another. None were like Reeve, who couldn't move anything. Exactly what's going on biologically with patients is open to question. Scientists speculate that activity may do more than trigger the pattern generator - that it may strengthen slender connections in the spinal cord that survived injury. While acknowledging that he is part of a growing movement, McDonald says he has a grander vision than most in the field. Cycling and other repetitive movements, he says, may actually spark the regeneration of nerves, a process that may take years to achieve. It may also prime the body to benefit from a future stem cell treatment. "What we say is this - there is hope," he says. "We don't remove the hope."
Lifelong treatment Patients wanting to continue a lifelong program can purchase an electrical stimulator for about $15,000 and weights that can be strapped to arms and legs. First, the patients need to complete six weeks of outpatient therapy at Kennedy Krieger, which can cost $12,000. Midway through the program, Beckman could be the type of patient who could benefit most, said Dr. Cristina Sadowsky, who left St. Louis to serve as the center's clinical director. She likes Beckman's chances because he isn't completely paralyzed, which gives him some neurological activity to build upon. Before he came to Kennedy Krieger, she said, he relied too much on getting around with a platform walker, a scaffold on wheels that helped compensate for his weakness. It did nothing, she said, to challenge nonfunctioning nerves and muscles. "We need to go back and establish a normal pattern," Sadowsky said. Though she refuses to predict his outcome, Beckman insists he has big plans - "to get up and throw a fastball again." "There's no sense in just walking," he said. "Everyone sets goals like that. You've got to do something no one else will do." Copyright © 2005, The Baltimore Sun
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