In a study conducted at UCLA, five men who had been
completely paralyzed were able to move their legs in
a rhythmic motion thanks to a new, noninvasive
procedure that stimulates the spinal cord. It is
believed to be the first time voluntary leg
movements have ever been relearned in completely
paralyzed patients without surgery.
The finding suggests that stimulation may help
reactivate dormant nerve connections between the
brain and spinal cord in some paralyzed patients.
Last year, NIH-funded researchers reported that a
surgically implanted stimulating device allowed 4
men to regain some leg movement after spinal cord
injuries had left their voluntary muscles completely
paralyzed below the chest.
Earlier this year, a team led by Gerasimenko and
Edgerton, along with Ruslan Gorodnichev of Russia’s
Velikie Luky State Academy of Physical Education and
Sport, demonstrated that they could induce
involuntary stepping movements in healthy, uninjured
people using noninvasive stimulation. The finding
led Drs. V. Reggie Edgerton to believe the same
approach could be effective for people with complete
paralysis.
In a follow-up study, the scientists—led by Drs. V.
Reggie Edgerton and Yury Gerasimenko of the
University of California, Los Angeles—tested a
nonsurgical strategy for stimulating the spinal
cord. Called transcutaneous stimulation, the method
delivers electrical current to the spinal cord via
electrodes strategically placed on the skin over the
spine.
The work was funded in part by NIH’s National
Institute of Biomedical Imaging and Bioengineering (NIBIB),
National Center for Advancing Translational Sciences
(NCATS), and other NIH components. Results were
reported in the online edition of Journal of
Neurotrauma.
Five men—each paralyzed for more than 2
years—received 18 weekly sessions of the spinal
stimulation for about 45 minutes.
The sessions also included muscle conditioning, in
which therapists manually moved the patients’ legs
in a step-like pattern.
During the final 4 weeks, the men received
twice-daily doses of buspirone. This drug has been
shown to induce mobility in mice with spinal cord
injuries.
The men were instructed at different points during
spinal stimulation to try to move their legs or to
remain passive. During these sessions, their legs
were supported by braces hung from the ceiling, so
they could move without resistance from gravity.
Initially, the men’s legs moved only when spinal
stimulation was strong enough to generate
involuntary step-like movements. But after 4 weeks,
the men were able to double their range of motion
when voluntarily moving their legs during
stimulation. The addition of buspirone further
improved their movements and by the end of the
study, they were able to move their legs with no
stimulation at all. On average, their range of
movement equaled that during spinal stimulation.
Researchers placed electrodes at strategic points on
the skin, at the lower back and near the tailbone
and then administered a unique pattern of electrical
currents. The electrical charges caused no
discomfort to the patients, who were lying down.
“The fact that they regained voluntary control so
quickly must mean that they had neural connections
that were dormant, which we reawakened,” said
Edgerton, who for nearly 40 years has conducted
research on how the neural networks in the spinal
cord regain control of standing, stepping and
voluntary control of movements after paralysis. “It
was remarkable.”
The men in the newest study ranged in age from 19 to
56; their injuries were suffered during athletic
activities or, in one case, in an auto accident. All
have been completely paralyzed for at least two
years. Their identities are not being released.
The researchers recorded electrical signals of the
men’s calf muscles while they attempted to flex
their feet during stimulation. Over time, the
signals increased with the same amount of
stimulation, suggesting a re-establishment of
communication between the brain and spinal cord.
“It’s as if we’ve reawakened some networks so that
once the individuals learned how to use those
networks, they become less dependent and even
independent of the stimulation,” Edgerton says.
Although the movements achieved in this study aren’t
comparable to walking, the results represent
progress toward a potential therapy for spinal cord
injury. The team is now assessing whether these 5
men can be trained to fully bear their weight, an
accomplishment that the 4 men with surgically
implanted stimulators have achieved.
For more information
Journal of Neurotrauma
University of California UCLA
MDN |