Brain Remapping Reversible In A 10-Year Old Recipient Of A Double Hand Transplant

Zion, a 10 year old, who underwent the first successful double hand transplant also happens to be the first child in whom brain reorganization was observed. While Zion had massive reorganization after his limbs were amputated, the team has found that after transplantation his brain remapping has started reverting to its normal pattern. This has brought back function into Zion’s newly transplanted hands. The study was conducted by research teams from the Children’s Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania and published in the Annals of Clinical and Translational Neurology.

Advertisement

Zion’s Story

Zion Harvey was born a normal child with hands and legs. But when he was two, an unfortunate sepsis required the amputation of both his upper and lower limbs. He had also received a kidney transplant at the age of 4, following kidney failure. In 2015, 10 year old Zion was the world’s first successful double hand transplant recipient.

Advertisement

Brain remapping

Each area of the body that receives a sensory input like the hands, feet, or lips has a specific location in the brain that perceives the corresponding sensory input that they send back. This is called the somatosensory representation where a particular area of the brain reflects a part of the body. However, when any part of the body stops receiving the input due to reasons like amputations where the specific part is detached from the body, the brain remaps itself. The brain remapping that occurs after amputation of the upper limb is called massive cortical reorganization (MCR).

"We know from research in nonhuman primates and from brain imaging studies in adult patients that, following amputation, the brain remaps itself when it no longer receives input from the hands," said William Gaetz, PhD, first author from the Biomagnetic Imaging Laboratory at Children’s Hospital of Philadelphia. "The brain area representing sensations from the lips shifts as much as 2 centimeters to the area formerly representing the hands."

Advertisement

Study Overview

While the team that worked with Zion believe that his brain reorganization started 6 years before he received the transplant, the highlight was that, following amputation the reorganization started to revert back to normal somatosensory network.

Magnetoencephalography (MEG) was used to measure magnetic activity in Zion’s brain and in specific, to detect the location of the brain, signal strength and timing of Zion’s response to sensory stimuli. The MEG’s were conducted four times in the year after the transplant. The same was also done on five healthy control children of the same age.

Zion’s transplanted finger tips did not respond to touch during the first two visits. Also, when his lips were touched, the MEG signal was found in the hand area of the brain’s cortex instead of the lip area. Moreover there was a 20 millisecond delay compared to the healthy controls. During the last two visits, when fingertips were stimulated MEG signals appeared in the hand region of the brain. Also, MEG signals from lip stimulation had returned to the lip region of the brain with a normal response time. Zion’s brain that had remapped after amputation was slowly beginning to revert to normal as his new hands were receiving sensory input.

This is what L. Scott Levin, MD, FACS, chairman of Orthopedic Surgery and a professor of Plastic Surgery at Penn Medicine, and director of the Hand Transplantation Program at CHOP, who lead the 40 member team that operated on Zion had to say:

"With the changes observed in his brain, which our collaborative team has been closely evaluating since his transplant two years ago, Zion is now the first child to exhibit brain mapping reorientation. This is a tremendous milestone not only for our team and our research, but for Zion himself. It is yet another marker of his amazing progress, and continued advancement with his new limbs."

Reference:

1. W. Gaetz, et al, “Massive cortical reorganization following bilateral transplants of the hands: evidence from the first successful bilateral pediatric hand transplant patient,” Annals of Clinical and Translational Neurology, Dec. 6, 2017.

Source-Medindia