A dual-therapy approach combining a brain-computer interface (BCI) with functional electrical stimulation may help stroke patients recover greater use of their impaired arm—even years after the stroke occurred.
Scientists at the Defitech Foundation Chair in Brain-Machine Interface, in association with other members of Ecole Polytechnique Fédérale de Lausanne’s (EPFL) Center for Neuroprothetics, the Clinique Romande de Réadaptation in Sion, and the Geneva University Hospitals, conducted the study, published in Nature Communications.
“The key is to stimulate the nerves of the paralyzed arm precisely when the stroke-affected part of the brain activates to move the limb, even if the patient can’t actually carry out the movement. That helps re-establish the link between the two nerve pathways where the signal comes in and goes out,” says José del R. Millán, who holds the Defitech Chair at EPFL.
The study included 27 patients ages 36 to 76, all of which had a similar lesion that resulted in moderate to severe arm paralysis following a stroke that occurred at least 10 months earlier. Half of the patients were treated with the scientists’ dual-therapy approach and reported clinically significant improvements. The other half were treated only with FES and served as a control group, according to a media release from Ecole Polytechnique Fédérale de Lausanne.
In the first group, the scientists used a BCI system to link the patients’ brains to computers using electrodes. That let the scientists pinpoint exactly where the electrical activity occurred in the brain tissue when the patients tried to reach out their hands. Every time that the electrical activity was identified, the system immediately stimulated the arm muscle controlling the corresponding wrist and finger movements.
The patients in the second group also had their arm muscles stimulated, but at random times. This control group enabled the scientists to determine how much of the additional motor-function improvement could be attributed to the BCI system.
The scientists noted a significant improvement in arm mobility among patients in the first group after just 10 1-hour sessions. When the full round of treatment was completed, some of the first-group patients’ scores on the Fugl-Meyer Assessment—a test used to evaluate motor recovery among patients with post-stroke hemiplegia—were more than twice as high as those of the second group, the relese explains.
“Patients who received the BCI treatment showed more activity in the neural tissue surrounding the affected area. Due to their plasticity, they could help make up for the functioning of the damaged tissue,” Millán says.
Electroencephalographies (EEGs) of the patients clearly showed an increase in the number of connections among the motor cortex regions of their damaged brain hemisphere, which corresponded with the increased ease in carrying out the associated movements.
What’s more, the enhanced motor function didn’t seem to diminish with time. Evaluated again 6 to 12 months later, the patients hadn’t lost any of their recovered mobility.
[Source(s): Ecole Polytechnique Fédérale de Lausanne, Science Daily]