IEEE Spectrum November, 2013 - 48

nOv 2013

nORTh aMERICan

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The breakthrough, published in The Lancet, shocked doctors
who had previously tried electrically stimulating the spinal nerves
of experimental animals and people with spinal-cord injuries.
In decades of research, they had come nowhere near this level of
success. "This had never been shown before-ever," says Grégoire
Courtine, who heads a lab focused on spinal-cord repair at the Swiss
Federal Institute of Technology in Lausanne and was not involved
with the project. "Rob's is a pioneer recovery. And what was surprising to me was that his was better than what we've seen in rats.
It was really exciting for me to see."
The report brought renewed hope for people living with paralysis.
The prognosis is normally grim for someone like Shillcox, who has
a "motor complete" spinal-cord injury. That level of damage usually results in a total loss of function below the injury site.
Teams of scientists have been working on transplanting stem cells
for neural repair and modifying the spinal cord in other ways to
encourage it to grow new neurons, but these long-term approaches
remain mostly in the lab. Harkema's breakthrough, however, produced a real human success story and gives hope to paralyzed people
everywhere. It presents a viable means of regaining bowel, bladder,
and sexual functions, and maybe-just maybe-points the way toward
treatments that could give paralyzed people the ability to walk again.
But Harkema's first experiment involved only one patient, and
many researchers wondered whether the improvement they saw
in Summers was an anomaly. "The next big question was, Will you
ever see these things in more than one subject?" says neurobiologist
V. Reggie Edgerton of the University of California, Los Angeles,
a collaborator in the Louisville experiments.
The U.S. Food and Drug Administration (FDA) had given Harkema
the go-ahead to try the technique in four more paralyzed people.
Shillcox put his name in the pool the night he saw the news report.
He was selected, and in July 2012 he packed his wheelchair into
his retrofitted Dodge Journey and drove himself from Green River
to Louisville to begin 18 months of experiments.

the circuitry of the lower spinal cord is impressively sophisticated.
Neuroscientists believe that the brain merely provides high-level
commands for major functions, like walking. Then the dense neural
bundles in the lower spinal cord take over the details of coordinating the muscles, allowing the brain to focus on other things. That
division of labor is what lets you navigate a party and focus on the
conversation rather than on your steps. After a spinal-cord injury,
damage prevents the high-level signal from the brain from reaching
the neurons below. Yet those neural bundles remain intact and are just
waiting to receive a signal to start the muscles working. Stimulating
the lower spinal cord with electrodes can awaken that circuitry and
get it functioning, astonishingly, without instructions from the brain.
It has been known since the mid-1970s that direct stimulation of
the spinal cord can actually induce the legs to move as if they were
taking steps, without any input from the brain. Edgerton and other

previous pages, x-ray: susan harkema/the lancet/elsevier

ustin Shillcox fully embraced
the vast landscape of his native
Wyoming. He loved snowmobiling,
waterskiing, and riding four-wheelers
near his hometown of Green River. But
on 26 August 2010, when he was 26 years
old, that active lifestyle was ripped away.
While Shillcox was driving a work van
back to the family store, a tire blew out, flipping the
vehicle over the median and ejecting Shillcox, who
wasn't wearing a seat belt. He broke his back, sternum,
elbow, and four ribs, and his lungs collapsed.
Through his five months of hospitalization,
Shillcox's family remained hopeful. His parents
lived out of a camper they'd parked outside the
Salt Lake City hospital where he was being treated
so they could visit him daily. His sister, Ashley
Mullaney, implored friends and family on her blog
to pray for a miracle. She delighted in one of her first
postaccident communications with her brother:
He wrote "beer" on a piece of paper. But as Shillcox's
infections cleared and his bones healed, it became
obvious that he was paralyzed from the chest down.
He had control of his arms, but his legs were useless.
At first, going out in public in his wheelchair was
difficult, Shillcox says, and getting together with
friends was awkward. There was always a staircase
or a restroom or a vehicle to negotiate, which
required a friend to carry him. "They were more
than happy to help. The problem was my own selfconfidence," he says.
A few months after being discharged from the
hospital, in May 2011, Shillcox saw a news report
announcing that researchers had for the first time
enabled a paralyzed person to stand on his own.
Neuroscientist Susan Harkema at the University of
Louisville, in Kentucky, used electrical stimulation to
"awaken" the man's lower spinal cord, and on the first
day of the experiments he stood up, able to support
all of his weight with just some minor assistance
to stay balanced. The stimulation also enabled the
subject, 23-year-old Rob Summers, to voluntarily
move his legs in other ways. Later, he regained some
control of his bladder, bowel, and sexual functions,
even when the electrodes were turned off.

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2013