Wednesday, May 17, 2017

Restoration of reaching and grasping movements through brain-controlled muscle stimulation in a person with tetraplegia

Ajiboye AB, Willett FR, Young DR, Memberg WD, Murphy BA, Miller JP, Walter BL, Sweet JA, Hoyen HA, Keith MW, Peckham PH, Simeral JD, Donoghue JP, Hochberg LR, Kirsch RF. Restoration of reaching and grasping movements through brain-controlled muscle stimulation in a person with tetraplegia: a proof-of-concept demonstration. Lancet. 2017 May 6;389(10081):1821-1830.

People with chronic tetraplegia, due to high-cervical spinal cord injury, can regain limb movements through coordinated electrical stimulation of peripheral muscles and nerves, known as functional electrical stimulation (FES). Users typically command FES systems through other preserved, but unrelated and limited in number, volitional movements (eg, facial muscle activity, head movements, shoulder shrugs). We report the findings of an individual with traumatic high-cervical spinal cord injury who coordinated reaching and grasping movements using his own paralysed arm and hand, reanimated through implanted FES, and commanded using his own cortical signals through an intracortical brain-computer interface (iBCI).
We recruited a participant into the BrainGate2 clinical trial, an ongoing study that obtains safety information regarding an intracortical neural interface device, and investigates the feasibility of people with tetraplegia controlling assistive devices using their cortical signals. Surgical procedures were performed at University Hospitals Cleveland Medical Center (Cleveland, OH, USA). Study procedures and data analyses were performed at Case Western Reserve University (Cleveland, OH, USA) and the US Department of Veterans Affairs, Louis Stokes Cleveland Veterans Affairs Medical Center (Cleveland, OH, USA). The study participant was a 53-year-old man with a spinal cord injury (cervical level 4, American Spinal Injury Association Impairment Scale category A). He received two intracortical microelectrode arrays in the hand area of his motor cortex, and 4 months and 9 months later received a total of 36 implanted percutaneous electrodes in his right upper and lower arm to electrically stimulate his hand, elbow, and shoulder muscles. The participant used a motorised mobile arm support for gravitational assistance and to provide humeral abduction and adduction under cortical control. We assessed the participant's ability to cortically command his paralysed arm to perform simple single-joint arm and hand movements and functionally meaningful multi-joint movements. We compared iBCI control of his paralysed arm with that of a virtual three-dimensional arm. This study is registered with, number NCT00912041.
The intracortical implant occurred on Dec 1, 2014, and we are continuing to study the participant. The last session included in this report was Nov 7, 2016. The point-to-point target acquisition sessions began on Oct 8, 2015 (311 days after implant). The participant successfully cortically commanded single-joint and coordinated multi-joint arm movements for point-to-point target acquisitions (80-100% accuracy), using first a virtual arm and second his own arm animated by FES. Using his paralysed arm, the participant volitionally performed self-paced reaches to drink a mug of coffee (successfully completing 11 of 12 attempts within a single session 463 days after implant) and feed himself (717 days after implant).
To our knowledge, this is the first report of a combined implanted FES+iBCI neuroprosthesis for restoring both reaching and grasping movements to people with chronic tetraplegia due to spinal cord injury, and represents a major advance, with a clear translational path, for clinically viable neuroprostheses for restoration of reaching and grasping after paralysis.
National Institutes of Health, Department of Veterans Affairs.

“What we are doing is restoring the ability to move from Point A to Point B and interact with simple objects,” lead author A. Bolu Ajiboye, PhD, assistant professor of biomedical engineering at Case Western University, told Neurology Today. “Our goal is to restore some level of independence to people who don't have it because of the severity of their spinal cord injury.”

Dr. Ajiboye cautioned: “We are not claiming to cure spinal cord injury. We are circumventing the injury and providing another pathway for brain signals to get through.”

The researchers' enthusiasm was seconded by an accompanying commentary piece in The Lancet that noted that the study is groundbreaking as the first report of a person executing functional, multi-joint movements of a paralyzed limb with a motor neuroprosthesis.

The commentator, Steve Perlmutter, PhD, research associate professor of the University of Washington, noted that while “this treatment is not nearly ready for use outside the lab...the future of motor neuroprosthetics to overcome paralysis is brighter.”

The project is part of a multicenter research effort called BrainGate that is developing brain-computer interface technologies to restore movement to persons with spinal cord injuries, brainstem stroke and movement-limiting neurologic diseases such as amyotrophic lateral sclerosis (ALS)….

Bill Kochevar, a 56-year-old Army vet, was on a 150-mile bike trek in 2006 when his bike crashed into the back of a mail truck on a rainy day, resulting in tetraplegia. Eight years after the accident, he learned through his doctor at the Louis Stokes Cleveland Veterans Affairs Medical Center, where he lives, about a trial called BrainGate2 that was testing the concept of a neuroprosthesis. He volunteered.

Researchers first implanted two microelectrode arrays in the area of the motor cortex controlling the hand and arm movements. To train the device, hundreds of brain signals were recorded as Kochevar received instructions to move a virtual arm on a computer screen in various directions. The recordings were analyzed to create a computerized program that recognized patterns in brain activity that were directly related to the movements he wanted to make. The next step came four months later when 36 percutaneous electrodes were implanted in the patient's right upper and lower arm to electrically stimulate muscles in his hand, elbow and shoulder.

The electrode system was used to condition the muscles to improve strength and movement and reduce muscle fatigue in preparation for doing tasks. The setup involved an arm support, also controlled by the brain, to keep his arm from being pulled down by gravity.

When the system was turned on for testing sessions in a VA lab, Kochevar was able to use his paralyzed arm and hand to perform some basic tasks, including grasping and drinking from a cup and feeding himself.

Using his paralyzed arm, the participant could reach to drink a cup of coffee (successfully completing 11 of 12 attempts within a single session 463 days after electrodes were implanted) and feed himself (717 days after the implants were placed), the researchers reported.

The movements were slow, a bit jerky, and not completely on target, but the researchers said further refinement in the technology would likely lead to more natural movement. Another downside is that the patient has to be “plugged into” the technology. The goal is to make it fully implantable, portable, and operational 24/7 in a person's home. Another long-term goal is to add a sensory component, since many movements, such as picking up an object, rely heavily on the sense of touch…

Neuroprosthetics may offer an advantage over robotic device control for persons with paralysis because “using one's own hands may make a person feel more whole, in a holistic way,” he said. “The neuroprosthetic technology provides more of a restoration of function rather than just a substitution to achieve a functional goal,” he added.

But even if the technology were refined to the point of being portable and accessible to patients outside of a research setting, Dr. Gorman [Peter Gorman, MD, FAAN, associate professor of neurology and division chief of rehabilitation medicine at University of Maryland School of Medicine] said, it likely would not be for all spinal cord injured patients. Other biologic interventions in development such as the use of stem cells to repair the spinal cord are also promising, yet still unproven, approaches, he said.

“There won't be one magic bullet,” Dr. Gorman said, “but rather a combination of biological, engineering and rehabilitative techniques that in combination will offer the most hope for recovery after spinal cord injury.”


No comments:

Post a Comment