When Dr. Milos R. Popovic dreams of brilliant control systems, it’s not supercomputers or NASA mission control he’s thinking of, it’s the human brain.
“The brain is the most sophisticated control system anywhere in existence,” says the biomedical engineer and Toronto Rehab senior scientist.
Dr. Popovic marvels, in particular, at the phenomenon known as ‘neuroplasticity’ the brain’s remarkable ability to adapt and perform new tasks, even after an injury. And he’s developed a way to make use of this ‘plasticity’ to help stroke and spinal cord injury survivors who have lost key functions, like the ability to grasp, reach or walk.
“With these injuries, the brain is damaged and some of its control mechanisms are gone,” he explains. “Motor or sensory commands cannot be relayed from the brain to the muscles, or from the muscles back to the brain. But the fact is that some of the neuronal cells can be retrained to do new tricks.”
Here’s how Dr. Popovic and Toronto Rehab’s Neural Engineering and Therapy Team are teaching injured brains to perform new tasks with extraordinary results:
First, the patient is asked to imagine a movement that he or she wants to do but cannot, such as grasping a glass. “This engages the brain in creating signals. But the signals cannot go anywhere due to the injury,” explains Dr. Popovic.
At the same time, an external device is used to stimulate the person’s muscles with tiny bursts of electricity. This causes the desired movement to actually happen. “As the hand moves, the patient gets sensory feedback from the movement, plus visual feedback from seeing his or her hand move,” he adds.
The whole process is repeated many times. The idea is that, after many repetitions, the patient can perform the movement on his or her own without the device.
But how can this be?
“The combination of the desire to move and the sensory feedback flowing to the brain causes changes in the brain’s circuitry,” Dr. Popovic says. “It forces the brain to adapt and form new neural pathways to control movement. Neuronal cells are forced to take more responsibility.”
It’s possible something else is going on too. “The brain creates stem cells all the time. And those new stem cells have to decide whether they will become neurons or supporting tissue in the brain. If there’s a lot of activity someplace, they will probably go there to assist.” Dr. Popovic hopes to prove this hypothesis with brain-imaging studies.
It’s clear that patients are benefiting, and significantly so, from Dr. Popovic’s novel use of functional electrical stimulation (FES). The new treatment approach has already helped some stroke and spinal cord injury survivors to reach and grasp again in some cases, years after injury.
In a landmark study published this year in the journal Neurorehabilitation and Neural Repair, Dr. Popovic and colleagues proved the power of FES therapy. Tested in a randomized clinical trial, their approach worked considerably better than conventional occupational therapy alone to increase spinal-cord injured patients’ ability to pick up and hold objects.
What’s more, the nine study participants who received stimulation therapy also saw big improvements in their independence and ability to perform everyday activities such as dressing and eating.
“This has real implications for people’s quality of life and independence, and for their caregivers,” says Dr. Popovic. “Even small improvements in the ability to perform daily activities can have a large impact on people’s lives.” Every year, millions of people worldwide have strokes and spinal cord injuries.
Dr. Popovic’s team is working hard to put its approach into widespread use at hospitals, physiotherapy clinics and in people’s homes. The researchers have almost completed a prototype of a stimulator for clinicians to use.
At Toronto Rehab, Dr. Anthony Burns, Medical Director of the hospital’s spinal cord rehabilitation program, says he will work with Dr. Popovic “to make this intervention available to our patients, and to answer important questions such as the duration of the effect.”
At Toronto Rehab, Dr. Popovic holds the Toronto Rehabilitation Institute Chair in Spinal Cord Injury Research. He is an associate professor in the Institute of Biomaterials and Biomedical Engineering at the University of Toronto.