In cervical spinal cord injury, the most severe of spinal cord injuries, around 20% of patients are left tetraplegic, with all four limbs partially or completely paralyzed. Tetraplegia is caused by a lesion on the spinal cord which prevents the nervous system from controlling all four limbs. Therefore, neuroprosthetics are highly desirable to manage this condition and improve the lives of patients.
BCI controls an exoskeleton
Now, a study from researchers at the University of Grenoble develops a brain-computer interface capable of controlling a whole-body exoskeleton that successfully helped a tetraplegic patient to move all four of his paralyzed limbs. The team states their findings move a step closer to enabling tetraplegic patients to control computers using brain signals alone. Additionally, starting with the control of wheelchairs using brain activity instead of joysticks and progressing to exoskeletons. The study is published in The Lancet Neurology journal.
Previous studies show brain-computer interfaces have used more invasive recording devices implanted beneath the outermost membrane of the brain, where they eventually stop working. These devices have also been connected to wires, limited to creating movement in just one limb, or focussing on restoring movement to patient’s muscles. The current study develops the first semi-invasive wireless brain-computer exoskeleton to control all four limbs.
The current study designs an implantable device, the WIMAGINE, which collects brain signals in the sensorimotor cortex emitted when a person imagines moving. The clinical trial tests the device on a 28-year-old tetraplegic patient with a lesion on his spinal cord.
Two WIMAGINE devices were implanted on the right and left sides of the upper sensorimotor area of the brain, above the patient’s dura mater. Throughout the 24 months of the study, the patient did various mental tasks to progressively increase the movement of their limbs.
The lab states the patient practiced in virtual environments with an exoskeleton avatar at home three times a week and worked directly with the exoskeleton and harness one week every month in the clinic.
Brainwave controlled exoskeleton
They go on to add when fitted with the suspended exoskeleton, the patient was able to take several successive steps. He was also able to control his two upper limbs in three dimensions and rotate his wrists whilst sitting or standing. The group stresses that even though the suit is an experimental treatment far from clinical application, it has the potential to improve patients’ quality of life and autonomy.
The team surmises they have provided proof-of-concept for their robotic system to enable a tetraplegic man to move his arms and walk. For the future, the researchers state three further patients have been recruited, with the next goal of the trial enabling patients to walk and balance autonomously without using a ceiling suspension system.
Source: The French Alternative Energies and Atomic Energy Commission (CEA)
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