In double transplant, left hand works first
Brain connection restored quicker, researchers find
WASHINGTON - When patients had both hands transplanted, their brains reestablished connections much more quickly with the left hand than the right, researchers in France report.
The sample was just two patients, but both had been right-handed, and both followed a pattern of reconnection with their brains that was quicker for the left hand.
The study, led by Angela Sirigu of the Center for Cognitive Neuroscience at the University of Lyon, was reported in yesterday's edition of the Proceedings of the National Academy of Science.
The research shows that even years after the loss of hands the brain can reorganize and rewire itself to recognize and connect to a replacement.
It comes just days after French physicians, in a 30-hour operation, performed the world's first simultaneous partial-face and double-hand transplant. Paris' Public Hospital Authority described the recipient as a 30-year-old burn victim who was injured in a 2004 accident.
Sirigu's team used magnetic imaging to study the brains of people who had lost both hands and to see how the motor region that controls movement responded after the transplants.
When body parts such as the hands are lost, the brain area controlling them doesn't become inactive, but instead begins relating to other nearby limb muscles, the researchers said. Those new connections can lead to patients still sensing the missing part or feeling phantom pain.
In the new study, the researchers were seeking to better understand how that brain rewiring is reversed when the missing hands are replaced.
The first case involved LB, a 20-year-old man injured in 2000, who received the transplants in 2003 after having used artificial hand devices in the meantime.
"Interestingly, despite that LB was right-handed, and that after his amputation he used his prosthetic device mostly with his right hand, hand preference shifted from right to left after he had the graft," the study said.
The researchers said more study is needed to determine why the brain reconnected more efficiently to the left hand in these patients. Possibilities include a better connection to the left hand, factors in the way that the brain reorganizes itself during the process of the loss of a hand and its later replacement, or perhaps some preexisting difference in brain organization.
