Stroke patients who learned to use their minds to open and close a device fitted over their paralyzed hands gained some control over their hands after using the device for 12 weeks, according to a new study from Washington University (WashU) School of Medicine, St. Louis. By mentally controlling the device with the help of a brain-computer interface (BCI), participants trained the uninjured parts of their brains to take over functions previously performed by injured areas of the brain, the researchers said. The study was published May 26 in the journal Stroke.
The work is based on a discovery made about a decade ago by Eric Leuthardt, MD, a WashU professor of neurosurgery, of neuroscience, of biomedical engineering, and of mechanical engineering and applied science, and the study’s co-senior author; and David Bundy, PhD, the study’s first author and a former graduate student in Leuthardt’s lab who is now a postdoctoral researcher at University of Kansas Medical Center.
In general, areas of the brain that control movement are on the opposite side of the body from the limbs they control. But Leuthardt and Bundy had discovered that a small area of the brain played a role in planning movement on the same side of the body. For example, to move the left hand, specific electrical signals indicating movement planning first appear in a motor area on the left side of the brain. Within milliseconds, the right-sided motor areas become active, and the movement intention is translated into actual contraction of muscles in the hand.
A person whose left hand and arm are paralyzed has sustained damage to the motor areas on the right side of the brain, while the left side is frequently intact. This means many patients who have experienced a stroke can still generate the electrical signal that indicates an intention to move but the signal goes nowhere since the area that executes the movement plan has been damaged.
“The idea is that if you can couple those motor signals that are associated with moving the same-sided limb with the actual movements of the hand, new connections will be made in your brain that allow the uninjured areas of your brain to take over control of the paralyzed hand,” Leuthardt said.
That’s where the Ipsihand, a device developed by WashU scientists, comes in. The Ipsihand comprises a cap that contains electrodes to detect electrical signals in the brain, a computer that amplifies the signals, and a movable brace that fits over the paralyzed hand. The device detects the wearer’s intention to open or close the paralyzed hand, and moves the hand in a pincer-like grip, with the second and third fingers bending to meet the thumb.
To test the Ipsihand, co-senior author Thy Huskey, MD, an associate professor of neurology at the School of Medicine and program director of the Stroke Rehabilitation Center of Excellence at The Rehabilitation Institute of St. Louis, recruited 13 patients who had their first stroke six months or more in the past and who had moderate to severe stroke-related impairments. The participants were trained to use the device at home, and were encouraged to use it at least five days per week, for ten minutes to two hours per day. Participants underwent a standard motor skills evaluation at the start of the study and every two weeks throughout. The test measured their ability to grasp, grip, and pinch with their hands, and to make large motions with their arms. Among other things, participants were asked to pick up a block and place it atop a tower, fit a tube around a smaller tube, and move their hands to their mouths. Higher scores indicated better function. After 12 weeks of using the device, the patients’ scores increased an average of 6.2 points on a 57-point scale. Ten patients completed the study.
“An increase of six points represents a meaningful improvement in quality of life,” Leuthardt said. “For some people, this represents the difference between being unable to put on their pants by themselves and being able to do so.”
Each participant also rated his or her ability to use the affected arm and his or her satisfaction with the skills. Self-reported abilities and satisfaction significantly improved over the course of the study. The amount each patient improved varied, and the degree of improvement correlated with how well the device read brain signals and converted them into hand movements, not with time spent using the device.
“As the technology to pick up brain signals gets better, I’m sure the device will be even more effective at helping stroke patients recover some function,” Huskey said.
Editor’s note: This story was adapted from materials provided by WashU.
Neurosurgery resident Jarod Roland tries the Ipsihand. Photograph courtesy of the Leuthardt Lab.
