Years after suffering severe strokes, two patients who underwent electrical stimulation of specific spinal cord regions could once against move their arms and hands, researchers reported on Monday in Nature Medicine.
Currently, no treatments are effective for treating post-stroke paralysis of the arms and hands once it becomes chronic.
In the new study, funded by the U.S. National Institutes of Health, some of the improvements persisted for weeks after the stimulation device was switched off, the researchers also found.
In each patient, thin metal electrodes resembling strands of spaghetti were implanted on the surface of the spinal cord along the neck to stimulate so-called neural circuits, which are populations of interconnected nerve cells that can carry out specific functions when activated.
Similar technology is already being used to restore movement to the legs after spinal cord injury, but the wide range of motion of the arms and hands has made restoring that movement more challenging, the researchers said.
After the treatment, the two patients could perform tasks of varying complexity, such as grasping common household objects and opening a lock.
"By stimulating these sensory nerves, we can amplify the activity of muscles that have been weakened by stroke," study coauthor Douglas Weber of Carnegie Mellon University said in a statement. "Importantly, the patient retains full control of their movements: The stimulation is assistive and strengthens muscle activation only when patients are trying to move."
The researchers are enrolling additional trial participants to understand which stroke patients can benefit most from this therapy and how to optimize stimulation protocols for different severity levels.
