Thursday March 30 2017
The brain's motor cortex controls physical movement
"New technology allows tetraplegic man to move hand with thought," The Guardian reports. Implants, designed to replicate the function of the spinal cord, have allowed a man, paralysed from the neck down (tetraplegia), to regain some control of his arm and head.
Tetraplegia can result from traumatic injury to the spinal cord that stops the brain from sending signals, via the spinal cord, to the rest of the body.
This case involved a 53 year old man who had been left paralysed with no sensation below his shoulders after a spinal cord injury in a cycling accident.
Doctors in the US implanted an electrical device into the part of the brain that normally controls hand movement. This device was then linked, via a computer, to a series of implants in his arm.
The man was able regain the ability to control movement of his paralysed right arm and hand through his brain alone. He was able to achieve a high level of accurate movement of his elbow, wrist and hand. This meant that he could feed himself mashed potato with a fork, and reach out to grasp and then drink a cup of coffee.
These are exciting findings and definitely support the continued development and testing of this approach in other paralysed patients. However, it's important to bear in mind that this is early stage research described in only one patient so far. We can't be sure whether it will work for all paralysed patients, and as yet can only be used as part of the ongoing clinical trial in the US.
Where did the story come from?
The study was carried out by researchers from several institutions in the US and Switzerland, including Brown University, Harvard Medical School and the Wyss Center for Bio and Neuroengineering in Geneva. It was funded by the Department of Veterans Affairs and National Institutes of Health.
The study was published in the peer-reviewed scientific journal The Lancet. It is available on an open-access basis and is free to read online.
The study attracted a great deal of media attention. Coverage in the UK was accurate. The Guardian is one of the news services that also provide a video clip of the technology in action.
What kind of research was this?
This was a case report which described a new approach to treating chronic tetraplegia – a form of paralysis where the person has no movement in their torso or any of their limbs.
Researchers can get people's paralysed muscles to move through stimulating them electrically (called functional electrical stimulation or FES). This stimulation can be controlled by the person themselves using a part of the body they can still move – such as their head or facial muscles.
However, FES can only achieve relatively basic movements. The current study wanted to see if this movement could be controlled by the person's own brain. The researchers implanted a device into the brain to pick up electrical impulses, and connected this via a computer to the FES device.
In this case, the patient was a 53-year old man who suffered an injury to the spinal cord in his neck. FES records signals from the brain. These signals are then used to coordinate electrical stimulation of the peripheral muscles and nerves to reanimate paralysed limbs, restoring lost function.
Case reports are useful for doctors to document the detailed outcomes of treatment for one or two individual cases, often in uncommon or rare conditions, as "proof of concept" that an innovative approach actually works (or not). This helps them to develop potential treatment options for other patients with the same condition. However, it isn't possible to generalise findings from a case report and these results would have to be replicated in larger studies to be recommended as a treatment option for other individuals.
What did the research involve?
This study reported on a 53-year old male participant in the BrainGate2 clinical trial. BrainGate2 is an ongoing study which is collecting information on the safety of brain implanted devices that aim to allow people with tetraplegia to use their brains to control external devices or parts of their body.
The man in the current study had experienced traumatic injury to his spinal cord high up in his neck eight years before he enrolled in the trial. As a result, he had no sensation below the shoulder and could not voluntarily move his elbow or hand.
Doctors implanted the main brain-controlled FES system in December 2014. The brain implants were placed in a region of the brain that would normally control hand movement. They were connected to a computer which could "translate" impulses from this part of the brain into commands to move first a "virtual" 3D image of an arm over a four month period, and then the man's own arm.
To do this, the brain implants were connected to the FES part of the system, which consisted of 36 "electrodes" implanted into his right arm that can deliver electrical impulses to arm muscles. The man also had a mobile arm support to help reduce the strain of gravity on the arm, and to help him move his arm up and down at the shoulder (also controlled by his own brain).
The researchers assessed his ability to perform simple single and multiple-joint arm and hand movements. This case report documents findings until November 2016 (717 days – almost two years – after the implant).
What were the basic results?
The man was able to control the "virtual" arm, and was also consistently able to:
- achieve 80-100% success of single-joint movements of the elbow, wrist, hand and mobile arm support to particular "target" positions
- control movements involving multiple joints
- successfully used his paralysed arm on 11 out of 12 attempts to reach out to drink a cup of coffee (starting 463 days after the implant)
- feed himself mashed potato with a fork (starting 717 days after the implant)
For some movements (bending and stretching his elbow, using his mobile arm support to move his arm up and down), he was able to achieve targets just as quickly and as successfully as he could with the virtual arm. However, other movements were slower and less accurate than he could achieve with the virtual arm. Failed attempts were due to various factors including difficulty stopping the movement accurately, and muscle fatigue.
The patient was not able to make meaningful movements with his arm when the FES system was switched off. During the trial he was reported to have four adverse events related to the device, but these were minor and could be treated.
How did the researchers interpret the results?
The researchers concluded: "To our knowledge, this is the first report of a combined implanted FES+ [implanted brain-computer interface device] for restoring both reaching and grasping movements to people with chronic tetraplegia due to spinal cord injury, and represents a major advance".
This was a case report which described how a man who was paralysed from the shoulders down regained the ability to perform reaching and grasping movements using his own paralysed arm and hand controlled by his brain.
It was a "proof of concept" study to show that the approach – using a brain implant linked via a computer to "functional electrical stimulation" (FES) devices to deliver electrical stimulation to the muscles – could work. The next step will be to continue developing and studying the technique in more people.
These are exciting findings and pave the way for further development of this technique so that it can hopefully become a treatment option for patients with paralysis in the future. It's important to bear in mind that we don't yet know whether this technique will work for all patients with paralysis, and it is currently only allowed to be used as part of the ongoing clinical trial in the US. These trials need to show the implants are sufficiently safe and effective before they can be allowed to be used more widely.
Lead author of the research, Dr Bolu Ajiboye told the Guardian: "Our research is at an early stage, but we believe that this [technique] could offer individuals with paralysis the possibility of regaining arm and hand functions to perform day-to-day activities, offering them greater independence."