By Robert Preidt
WEDNESDAY, Dec. 6, 2017 (HealthDay News) – Two years ago, Zion Harvey was the first child to undergo a successful double-hand transplant. He is now gaining notoriety for another milestone: the way his brain reorganized in response to amputation and transplantation.
Harvey, now 10 years old, lost both hands due to a severe infection in childhood. The brain reconnected after the amputations, but reversed those changes after it received its transplanted hands, according to its doctors at the Children's Hospital of Philadelphia.
"With the changes observed in his brain, which our collaborative team has been evaluating since his transplant two years ago, Zion is now the first child to exhibit the reorientation of brain mapping," said the study's lead author, Dr. L. Scott Levin. He led the 40-member team that performed the hand transplant.
Every part of the body that receives nerve sensations sends signals to a corresponding site in the brain, Zion's doctors explained in a recently published case study.
Study first Author William Gaetz said: "We know from research in nonhuman primates and brain imaging studies in adult patients that, after an amputation, the brain is reassigned when it no longer receives information from the hands."
Cerebral reassignment that occurs after surgery Limb amputation is called massive cortical reorganization (MCR).
"We expected to see MCR in our patient, and in fact, we were the first to observe MCR in a child," said Gaetz, a radiology researcher at a hospital. press release
"The area of the brain that represents the sensations of the lips changes as much as 2 centimeters to the area that previously represented the hands," he explained.
But Gaetz said they were even more excited to observe what happened next – when the patient's new hands began to regain function.
"For our patient, we found that the process is reversible," he added.
Using advanced imaging, the researchers measured the magnetic activity in Zion's brain to detect the location, strength, and time of his responses to the stimuli applied to his lips and fingers. The researchers performed these tests four times in the year following the transplant.
Significant changes were detected in the two subsequent visits that indicated a better response time to the stimuli, a signal that the cerebral reassignment was returning to a normal pattern.
"The sensory signals are arriving at the correct location in the brain, but they may not yet be fully integrated into the somatosensory network," Gaetz said. "We hope that over time, these sensory responses will become more typical of age."
Zion has been the son of many firsts at Penn Medicine and around the world, said Levin, director of the hospital's hands-on transplant program.  "This is a tremendous milestone not only for our team and our research, but for Zion himself," said Levin. "It's another sign of his incredible progress and continuous progress with his new limbs."
Gaetz said that these results have generated new questions and enthusiasm about brain plasticity, particularly in children.
Some of these new questions include, what is the best age for a hand transplant? Does brain reorganization always occur after amputation? How is brain mapping seen in people who are born without hands?
"We are planning new research to investigate some of these questions," said Gaetz.
As for Zion, he can now write, dress and feed himself more independently than before his operation. These are "important considerations to improve your quality of life," Levin said.
The report was published on December 6 in the journal Annals of Clinical and Translational Neurology .