'Brain training' helps eight paralyzed people regain some movement
The step-by-step training appears to jump-start the connection between brain and body through the use of virtual reality walking simulations, specially designed exoskeletons and tactile feedback, said senior researcher Dr. Miguel Nicolelis. He is director of the Duke University Center for Neuroengineering.
Weekly training with these machines re-awakened undamaged but unused spinal cord nerves that had survived the car crashes, falls and other accidents that caused paralysis, he said.
"These patients didn't have any movement of their limbs and they didn't have any tactile feeling below the level of their injury," Nicolelis said. "After one year of training, half of these patients had to be reclassified as partial paraplegic, because we could document voluntary movements from these patients."
The patients also regained some level of bladder control and bowel function that had been lost due to their spinal cord injury. "They were able for the first time in many years to control their bathroom routine," Nicolelis said.
The eight patients all had sustained spinal cord injuries that left their lower bodies completely paralyzed for between three years and 13 years, the researchers said.
At the beginning of the study, investigators asked the patients to think about walking while undergoing a brain scan. The scans found no activity at all in the regions of the brain associated with movement.
"That suggests to us the representation of the lower limbs and the idea of locomotion had almost been erased from the brain," Nicolelis said.
These patients' training regimen started with at least two hours a week spent in a virtual reality environment where their brains controlled the movement of a three-dimensional avatar walking across a soccer field, Nicolelis said.
An EEG (electroencephalogram) cap strapped to their heads monitored the brain areas that control movement, and translated signals into steps taken by the avatar. At the same time, a specially designed shirt produced tiny vibrations on their arms every time the avatar moved, providing tactile feedback of each step taken.
After months of such training, researchers began to see an increase in brain activity related to walking. "We are basically driving the brain to reinsert the idea of walking and reinsert the interpretation of the legs," Nicolelis said.
At that point, the patients moved on to more challenging exercises using equipment that allowed them to move their own bodies, rather than a virtual avatar.
One piece of equipment used a harness to suspend a patient over a treadmill, supporting their weight while a robotic device moved their legs using brain signals. Patients also were placed in a self-supported exoskeleton that took steps in concert with their brain signals.
In all cases, the patients continued to wear the feedback shirt, allowing the brain to receive tactile signals through the arms every time a step was taken, the study authors said.
After 12 months, all of the patients had experienced some recovery of muscle function and tactile sensation, the findings showed. Some were able to voluntarily move multiple joints in their legs, something they hadn't been able to do for years.
A 32-year-old woman paralyzed for 13 years experienced the most dramatic improvement, the researchers said. ■