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A new hand
-- and signs of sensory recovery
Newswise — Four months after a successful
hand transplant -- 35 years after amputation
in an industrial accident at age 19 -- a
54-year-old man’s emerging sense of touch is
registered in the former "hand area" of the
his brain, says a University of Oregon
neuroscientist.
The finding, appearing online in advance of
regular publication in the Oct. 14 issue of
the journal Current Biology, centers only on
the man's right palm of a donated hand,
which was attached along with major nerves,
bones, tendons, and muscle, in a surgery by
Kleinert, Kutz and Associates Hand Care
Center of Louisville, Ken.
A co-author, Dr. Warren C. Breidenbach, also
was the lead surgeon of the team that
performed the first long-term successful
hand transplant in 1999.
Still to be determined, said lead author
Scott H. Frey, UO psychology professor and
director of the Robert and Beverly Lewis
Center for NeuroImaging, is how the brain’s
map of the individual fingers will evolve
with increasing sensation.
Just four months post-surgery, initial touch
sensations were reported on the thenar
eminence -- muscle on the palm just below
the thumb -- and on the lateral base of the
thumb near the radial nerve.
Functional magnetic resonance imaging was
used to record brain activity while sensory
stimuli were delivered to the hands and
faces of the transplant recipient and four
control participants.
Results showed that sensory signals from the
transplanted hand are being processed in the
same brain regions that would have formerly
handled sensations from the hand prior to
amputation.
"This individual is very unique from a brain
standpoint," Frey said. "We know that when
someone loses a hand, there are
reorganizational changes that take place in
areas of the brain that have received
sensory input from that hand.
"Yet, even after 35 years, the restoration
of sensory input seems capable of
recapturing the former territory of the
hand. The capacity of the brain to reverse
these changes is all the more striking in
light of the fact that his brain was fully
mature when the amputation occurred.
"We
believe that this work may have far reaching
implications for our understanding of brain
plasticity in adulthood and
neurorehabilitation.”
The patient received the transplant in
December 2006. After losing his hand in a
machine press accident, he wore a standard
cable-hook-prosthetic device, allowing him
to continue working.
Reorganization in sensory regions begins
within hours of a limb loss. Research on
animals has shown that neurons that had been
devoted to receiving sensory inputs from the
limb take on new duties.
Exactly what happens is not entirely clear,
nor are we certain how long such changes
continue Frey said, "but one way to think
about it is that none of the brain's real
estate is left vacant for very long." Over
time, the injured man reported gradual
reductions of phantom sensations and pain
often reported by amputees.
Recovery of sensation and the brain's
systematic mapping of the hand-to-brain
network, in this case, involve only gross
hand map zones, referring to activity of
major nerves that were reattached, not any
peripheral connections to individual digits.
"We don't know what that map will look like
in the future as the nerves of his fingers
regenerate and sensation improves," Frey
said.
Physicians at the Hand Care Center have
performed four of the almost 30 hand
transplants done worldwide.
Advances in imaging technology are allowing
neuroscientists to map the brain before and
after surgeries, opening new insights into
brain reorganization and recovery, Frey
said.
"What this hand transplant allows us to ask
for the very first time in history is:
Following reorganizational changes, is it
possible to reverse the restoration of
sensory input into the brain? The answer,
which appears to be yes, extends well beyond
the case of hand transplants," he said.
"In general, it gives us some ideas about
the reorganizational potential of the
brain.”
Co-authors with Frey and Breidenbach were
Frey's UO colleagues Sergei Bogdanov,
Jolinda C. Smith and Scott Waltrous, all of
the Lewis Center for NeuroImaging. Funding
included grants from the M.J. Murdock
Charitable Trust based in Vancouver, Wash.,
the National Institute of Neurological
Disorders and Stroke of the National
Institutes of Health, U.S. Army Medical
Research and Material Command and the Office
of Naval Research.
About the University
of Oregon
The University of Oregon is a world-class
teaching and research institution and
Oregon's flagship public university. The UO
is a member of the Association of American
Universities (AAU), an organization made up
of 62 of the leading public and private
research institutions in the United States
and Canada. Membership in the AAU is by
invitation only. The University of Oregon is
one of only two AAU members in the Pacific
Northwest.
Links: Lewis Center for NeuroImaging:
http://lcni.uoregon.edu/index.html;
Kleinert Kutz Hand Care Center:
http://www.kleinertkutz.com/
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