Three people paralysed from the waist down have become the first to walk again using a new type of therapy. Doctors treated them with a mixture of electrical stimulation from spinal implants, plus gruelling months-long exercise regimes.
Two were treated at the University of Louisville’s Kentucky Spinal Cord Injury Research Center. Kelly Thomas, a 23-year-old from Florida injured in 2014 through a car accident, and Jeff Marquis, a 35-year-old from Wisconsin, broke his back in 2011 through a mountain-biking accident. The third patient, 29-year-old Jered Chinnock, was injured in a snowmobile accident in 2013, and received his treatment at the Mayo Clinic in Rochester, Minnesota.
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The treatment of all three was practically identical. Doctors treated Chinnock for almost a year with a mixture of electrical stimulation from a spinal implant, plus a 43-week exercise regime. As with the Louisville patients, the team at Mayo surgically implanted a panel of electrodes into his lower back, tuning it to feed signals into tissues of his spinal cord with connections to powerful muscles in the legs.
Bridge the gap
The break in Chinnock’s spine ruptured any direct link between his brain and the nerves that control leg muscles, but the researchers believe the implant is somehow able to bridge the gap. They think that some connections between the brain and the nerves controlling leg muscles might survive the injury, but are too weak alone to stimulate movement.
By tuning the electrical signals from the implant through trial and error, coupled with intensive exercise, the team were able to boost the signal from the brain enough to stimulate movement in the leg muscles.
After one month of the regime, the patient had begun standing on a treadmill. Aided at first by physiotherapists who moved his legs, plus a support system holding his upper body, the patient began exercises to intentionally step forward. Gradually, his ability to take steps on the treadmill improved.
Next, with the help of a front-wheeled walker and an assistant to guide his balance, he could walk a maximum of 331 steps in a single session on open ground, reaching a distance of 102 metres. Between weeks 25 and 42, his walking speed quadrupled from 5 to 20 centimetres a second.
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“I think it’s highly significant, because if you look at research over the past 50 years, there really hasn’t been much success,” says Kendall Lee of the Mayo Clinic, and joint principal investigator. “Even though it’s only one patient, being able to regain intentional control and moveĚý[100 metres] is incredibly significant, as it’s about the length of a football field.”
The regime for the two Louisville patients was very similar. With the help of a roller, Thomas could walk over open ground unaided by physiotherapists at the end of the treatment. Marquis was able to walk 362 metres during one, hour-long session, and reached a maximum walking speed of 19 centimetres a second, roughly the same as Chinnock.
“This work shows the ability of the spinal cord to re-learn years after injury,” says Claudia Angeli, who co-led the Louisville team, which reported earlier successĚýrestoring some movement to the legs of four paralysed patients using similar implants. “These are extremely exciting and important findings for the field of spinal cord injury research,” she says.
But it didn’t get everyone walking. Although two additional Louisville patients were able to stand, they couldn’t progress to walking, possibly because they lacked residual connections in their spinal cords to transmit the willpower to walk to the leg muscles via the implant.
“It’s quite exciting, but I wouldn’t say it would work for everyone,” says Andrew Jackson of Newcastle University, UK. “It might be important to try and establish biomarkers to show if patients have enough surviving connections to benefit from the procedure,” he says.
Arm control
The walking milestone coincides with an advance by another team enabling 27-year-old Ian Burkhart, a quadriplegic man from Dublin, Ohio, to intentionally control one of his arms, gripping and manipulating everyday objects.
A panel of electrodes implanted in the brain of Ian Burkhart, who was injured in a diving accident in 2010, is giving him unprecedented control over his right arm.
“Using our system, Ian was able to quickly and accurately interact with objects he encounters in his daily life, including picking up and moving a beverage can, pressing a fork into food and manipulating a small peg on a pegboard,” says David Friedenberg of Battelle Memorial Institute in Columbus, Ohio, and co-leader of the team that treated Burkhart. “Using standardised clinical tests, he was successful on 44 of his 45 attempts.”
Burkhart’sĚýtreatment relies on three key components. A microchip implanted in his brain’s motor cortex—which controls movement—feeds electrical signals from 96 locations into a device called a decoder. It uses machine-learning algorithms to interpret the electrical activity and predict how Burkhart wants to move his hand.
Finally, a sleeve on Burkhart’s right forearm accepts signals from the decoder as he is thinking. It is programmed to stimulate muscles in his forearm to carry out his intended actions.
Friedenberg says his team’s main innovations is an improved decoder which identifies and acts on Burkhart’s intentions faster, within less than a second. Also, unlike predecessors, it can learn on the fly without lengthy, painstaking prior calibration. “It brings us closer to a clinical system that someone like Ian can take home and use on a regular basis,” says Friedenberg.
Journal reference: Nature Medicine, ;
New England Journal of Medicine
Update:ĚýThis article has been updated to include additional people who have tried the spinal implant.
Article amended on 27 September 2018
We have corrected the device used to stimulate muscles in Ian Burkhart’s treatment
