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 A year after the surgery, "the paralyzed arm showed improved power,
function and reduced spasticity," they report in The New England
Journal of Medicine.
But the small study is sparking skepticism because the improvements
seemed to appear faster than nerves are typically able to grow.
Dr. Robert Spinner, chairman of neurosurgery at the Mayo Clinic in
Rochester, Minnesota, said it's possible the benefits were caused by
simply cutting the bad nerve leading to the affected arm, a much
simpler procedure than the nerve transfer surgery.
"These results are very exciting because this is a very big problem
in America and the world. The question really is, what's causing the
effect," he said in a telephone interview. "To cut the bad wire
would be a lot easier than doing their procedure."
The senior author of the study, Dr. Wen-Dong Xu of Fudan University,
did not respond to emailed questions.
The randomized trial involved 36 men at Huashan Hospital, all of
whom had at least some muscle power and the ability detect touch.
Their paralysis was due to brain injuries including strokes,
cerebral palsy and head trauma. On average, patients had been
paralyzed for 15 years and had undergone 10 years of rehabilitation.
In 18 patients, surgeons found a nerve feeding the affected arm -
the C7 nerve, which exits the spine at the base of the neck - and
severed it near the spinal cord. The C7 accounts for about 20% of
the nerve impulses going into an arm.
Then, on the other side of the spinal cord, surgeons cut the healthy
C7 nerve feeding the unaffected arm, rerouted it behind the
esophagus, and grafted it onto the nerve leading to the affected
arm. The hope was to give control of the paralyzed arm to a healthy
part of the brain.
The other 18 volunteers simply received the same four-times-per-week
rehabilitation regimen that the surgery group did.
On a 67-point movement scale, the surgery group collectively started
at 29.0 points and ended at 46.7 after 12 months. Volunteers in the
rehabilitation-only group went from 29.1 points to 31.7 points.
Before surgery, none of the patients could reach or grasp with the
paralyzed hand, and none could dress, tie shoes, wring out a towel,
or operate a mobile phone with the affected arm and hand,
researchers reported.
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After surgery, 16 of the 18 could perform at least three of those
tasks. None of the rehabilitation-only patients could.
There were side effects. Twelve patients in the surgery group
reported a strange feeling while swallowing and 15 reported fatigue.
In the healthy arm that originally got signals from the C7 nerve,
hand numbness was reported by 16 people, 16 said they couldn't
extend their wrists with as much force as they could before, 15 said
they couldn't extend their elbow as forcefully as before, and 16
reported lessened sensory function. The side effects often subsided
over time.
The Xu team acknowledged that just severing the nerve leading to the
paralyzed arm may have helped release the spasticity, making
rehabilitation easier. But they said there was evidence that nerve
cells were reconnecting the brain to the arm.
The results “are exciting but need clarification and confirmation,"
Spinner and two colleagues wrote in a Journal editorial.
They noted that nerves usually grow an inch per month, so 12 months
would not be enough time to make a direct connection from the spine
to the hand.
"Nerves do not regenerate that quickly, fully, or consistently,"
they said.
It's more likely that cutting the nerve produced the benefits by
stopping the hand and arm muscles from spasming, allowing other
nerves that move the arm to work more effectively, Spinner believes.
One way to test that would be to just cut the C7 nerve and see if
that is enough to produce the improvements, he said.
"In their paper they say they saw some improvements after one
month,” Spinner noted. “Certainly that can't be from regeneration.
Usually full results from long-distance regeneration take several
years."
SOURCE: http://bit.ly/2oXfJpu The New England Journal of Medicine,
online December 20, 2017.
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