Hand Transplant Study Provides New Information on Sense of Touch

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A small study from the University of Missouri in Columbia suggests that the ongoing recovery of feeling following a hand transplant or replant may be due to changes in the brain as much as changes in the hand. The research was presented today at a Society for Neuroscience meeting. Results of the study could offer new information on rehabilitation after brain injury, stroke or possibly even spinal cord injury. Researcher Dr. Scott Frey said the results provide hope that one day it might be possible to facilitate that recovery process.

Although hand transplant patients may begin to recover function fairly soon, there is wide variation in how quickly feeling is regained. In addition to stimulating nerves in the skin, the sense of touch depends on those nerves sending signals to specific areas of the brain, allowing the person to determine what they are touching and how to react. When a limb is lost the brain rewires, giving the neurons that formerly connected to the missing limb new functions. Brain scans show that those changes may possibly be at least partly reversed even if the hand transplant occurs years later.

A persistent problem for hand transplant patients has been regaining the ability to tell where they are being touched on the palms or fingers of the reattached hand. The study, which compared four patients who had their own hands immediately reattached after they were injured with 14 uninjured people, found that the longer it had been since the reattachment surgery, the more accurately the patients were able to locate a light touch. Two of the study participants who had their transplant surgery eight and 10 years before were able to distinguish touch almost as accurately as uninjured people. The other two hand transplant patients, who had their own hands reattached 1 1/2 years and 3 years earlier were almost as accurate.

Frey says it is thought to take about two years for nerves to regenerate. However, since the sensory and motor abilities continue to show gradual improvement, it suggests that the brain continues to adapt even after that ime. Determining where on the hand a touch occurs is a function of the brain’s main sensory area.

Dr. Gordon Shepherd, a Yale University neuroscientist unconnected to the study, says hand transplants offer a model for the brain’s ability to reorganize after injuries or stroke that are more difficult to study. He said that “it has quite broad implications” for recovery research.

Hand transplantation is relatively new and somewhat rare. The procedures began to be regulated last summer by the United Network for Organ Sharing, in the same manner that it tracks organ transplants. The registry is aware of about two dozen hand transplant recipients since 1999 in the U.S.

Richard Mangino, a painter and musician from Massachusetts, is the first patient to receive a successful double hand transplant, done in October 2011 at Boston’s Brigham and Women’s Hospital. Mangino lost both his lower legs and lower arms to infection in 2002. Dr. Simon Talbot said in August 2014 that Mangino is still making progress in gaining sensation and function in his new hands. He has returned to drawing and playing the piano.

By Beth A. Balen

Associated Press
Medical Press