Researchers in the US are attempting to connect data from sensors monitoring the brain, muscles and movement with a bilateral wearable exoskeleton, in an effort to give stroke survivors a more active role in their own rehabilitation.
Academics at Rice University and UTHealth Houston are looking to test the exoskeleton on stroke survivors, allowing a participant’s less-affected arm to drive movement in the more affected arm while simultaneously monitoring neural activity, muscle activation and movement
The project points towards a model of rehabilitation robotics in which machines do more than repeat prescribed movements, instead using data to understand how a patient is responding and potentially tailor therapy.
“The main goal is to understand whether this self-driven or mirror-mode therapy can be beneficial for stroke survivors,” said Keya Ghonasgi, assistant professor of mechanical engineering at Rice University. “This exoskeleton gives us a unique opportunity to test that because it is a bimanual device with a high degree of joint-level control. There really are not many upper-limb systems that can assist both arms in this way.”
The pilot study will recruit 10 stroke survivors who are at least six months into their recovery. Participants will perform movement tasks under several conditions, including without the exoskeleton, with active movement, with passive robot assistance and using the self-driven bilateral mode.
During the sessions, the researchers will synchronise three different types of measurement. Electroencephalography (EEG) will track brain activity associated with motor planning and engagement, electromyography (EMG) will measure activation in key arm and shoulder muscles, while motion data will capture factors including range of motion, coordination and smoothness.
“Simply moving someone’s affected arm with an exoskeleton is not enough,” Ghonasgi said. “It is a little like trying to learn tennis by having a coach move your arm for you.”
“We want the participant to be engaged in the movement, but we also know they may be limited by strength, fatigue, range of motion or coordination,” she added. “This approach could give them support while still asking them to actively drive the movement.”
For Simon Fischer-Baum, associate professor of psychological sciences at Rice University, the ability to capture neural and physical responses at the same time offers a way to investigate rehabilitation at a deeper level.
“We are trying to understand the basic science of recovery – what happens in the brain after damage and what kinds of activity may support rehabilitation,” he said. “With EEG, we can measure brain activity in real time and look for signatures of motor engagement, even before we see clear behavioural changes. That is what makes this project exciting: We can ask whether the brain is processing the movement differently when the patient is actively involved,” Fischer-Baum said.
The exoskeleton’s joint-level control also allows the team to examine whether patient-driven assistance has different effects depending on the movement being performed. The researchers will compare individual joint motions with more coordinated reaching tasks.
The researchers say that the pilot will not establish whether the technology produces lasting improvements in stroke recovery. Instead, it will establish whether the different modes of robotic assistance produce measurable differences in neural, muscular and movement-related activity.
“Our hope is that self-driven bilateral assistance will produce more brain activity than passive robotic movement alone,” Ghonasgi said. “We do not yet know whether that will translate into long-term rehabilitation gains, and that is exactly why this study is important.”
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