We've recently seen rehabilitative systems in which stroke victims use their thoughts either to move animated images of their paralyzed limbs, or to activate robotic devices that guide their limbs through the desired movements. Scientists at the University of Wisconsin-Madison, however, have just announced an alternative approach. Their device acts as an intermediary between the brain and a non-responsive hand, receiving signals from the one and transmitting them to the other.
Known as the Closed-Loop Neural Activity-Triggered Stroke Rehabilitation Device, it consists of two established technologies. The first of those is a brain control interface (BCI), which interprets electrical signals from the brain and uses them to control an external device – we've seen BCIs used before, to control robotic arms. In this case, though, it activates a functional electrical stimulation (FES) system that's attached to the paralyzed hand.
When a patient thinks of tapping their fingers, the BCI reads and recognizes those signals, passes them along to the FES, and it causes the hand to move as desired. The idea is that by repeatedly moving their hand in this fashion, patients will rebuild the neural pathways that previously allowed them to do so unaided.
In a test of the device, eight patients tried it out, all of whom had lost at least partial use of one hand due to stroke. Each one of them took part in 9 to 15 sessions with the device over three to six weeks, each session lasting from two to three hours. Before, during and after the trial, they were evaluated using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), the latter of which "reveals the integrity of fibers within the white matter that connects the brain's functional areas."
Although there was some variation depending on the severity of each person's stroke, overall the fMRI indicated that the sessions resulted in a reorganization of the parts of the brain involved in motor function, while the DTI showed a strengthening of fibers. In practical terms, patients experienced an improvement in motor function, and reported an improvement in their ability to perform daily activities.
"Our hope is that this device not only shortens rehabilitation time for stroke patients, but also that it brings a higher level of recovery than is achievable with the current standard of care," says Dr. Vivek Prabhakaran, who co-led the research with Dr. Justin Williams.
