Stroke patients can train the healthy part of their brain to perform some functions of the damaged regions for regaining partial mobility, researchers say.
Each year, about 800,000 Americans suffer a stroke: A blockage or internal bleeding causes disruption of blood flow to the victim's brain, which deprives a region from necessary oxygen and nutrients, and in turn causes damage. The brain injury very commonly results in weakness or partial paralysis in the limbs, limiting patients' mobility.
The paralysis is often on one side of the patient's body, opposite to the brain hemisphere that has suffered injury. That's because the brain's left hemisphere controls the right side of the body and vice versa. However, over the last several years, researchers have found that there are some same-sided control signals within a brain hemisphere—meaning there's a small pool of neurons allocated to controlling the same side of the body.
The trick is to harness those brain signals associated with same-sided limb movement to help restore some function to the paralyzed side of the body.
Dr. Eric C. Leuthardt, director of Center for Innovation in Neuroscience and Technology at Washington University School of Medicine in St. Louis, has been working to utilize these signals for thought-control of an external device that the patient wears over the paralyzed limb.
In this non-invasive approach, a patient with stroke in one hemisphere wears a cap on the head and thinks about moving a limb, such as a hand. The electrodes on the cap pick up his or her brain signals from the non-affected brain hemisphere, and relay that information to a computer. The computer then translates those signals to control the prosthetic device.
Image: A prosthetic that patients can wear over their arm. Credit: Neurolutions Inc.
"We have now created an integrated system that employs electroencephalography (EEG) signals and connects to a controllable robotic exoskeleton, which we refer to as the 'IPSI-Hand,'" Leuthardt says. "This system allows the stroke patient to open and close their paralyzed hand using their ipsilateral physiology, or brain signals associated with same-sided limb movements."
The technology, created by NeuroLutions, a company working to restore function to those suffering neurological injury, could have uses beyond just enabling a patient to control their paralyzed limbs. It could allow the limbs to regain strength and aid in reorganizing neural pathways.
"We are testing to see if the continued usage of this technology over time will lead to a fundamental rewiring of the brain so that paralyzed patients can recover natural hand function by having the uninjured side of the brain take over function that is lost by the side of the brain injured by stroke," Leuthardt says.
The researchers are currently conducting a clinical trial to test this rehabilitation approach for patients who have a persistent deficit after a stroke.
"We are working towards a real world clinical implementation," Leuthardt says. "The only obstacles are getting investment into the company to move this towards a widespread clinically deployed technology."