A stroke can cause permanent paralysis, even if a patient's cognitive functions recover. But those thoughts, if a revolutionary new robotic orthotic succeeds, could be all it takes to help stroke victims' bodies recover a greater degree of limb function.
Funded by a $US1.17 million grant from the National Institute of Health, a collaboration of research teams from Rice University, the University of Houston, and TIRR Memorial Hermann developed the device, dubbed the MAHI-EXO II. It employs a non-invasive EEG interface — in this case, an electrode-studded cap worn by the patient — to control the orthotic worn on the lower arm.
The EEG component was originally developed by José Luis Contreras-Vidal, director of UH's Laboratory for Noninvasive Brain-Machine Interface Systems, for use in cutting-edge neuroprosthetics. This brain cap essentially "reads" the electrical impulses generated in the brain when a patient thinks about, say, walking or grasping an item and then outputs those signals to the artificial limb, initiating motion with just a thought.
The orthotic hardware also has been adapted from its original purpose for this new system. Marcia O'Malley, director of Rice University's Mechatronics and Haptic Interfaces Lab, created the device, known as the RiceWrist, as a means to help spinal-cord injury sufferers regain motor function in their affected appendage. It acts much like a spotter does in weight lifting, providing gentle assistance to finish the exercise when the patient reaches his physical limit.
"We want the patients to move independently," O'Malley explained. "When they're unable to complete a movement or reach the end of a workspace, the robot kicks in. But the literature supports the idea that there needs to be some intentional movement to really reap the rewards of rehabilitation."
With time and practice, the body can eventually reroute motor control and regain a degree of function, strength and accuracy. "With a lot of robotics, if you want to engage the patient, the robot has to know what the patient is doing," O'Malley said in a press statement. "If the patient tries to move, the robot has to anticipate that and help. But without sophisticated sensing, the patient has to physically move — or initiate some movement."
Though still a prototype, the researchers hope to soon hold a two-year validation trial for the device at TIRR Memorial Hermann Hospital with 40 volunteer stroke survivors before beginning clinical trials. "The capability to harness a user's intent through the EEG neural interface to control robots makes it possible to fully engage the patient during rehabilitation," Contreras-Vidal said. "Putting the patient directly in the ‘loop' is expected to accelerate motor learning and improve motor performance. The EEG technology will also provide valuable real-time assessments of plasticity in brain networks due to the robot intervention — critical information for reverse engineering of the brain."
Image: Bruce French/TIRR Memorial Hermann