The Department of Defense is funding a new clinical trial to examine the use of targeted muscle reinnervation (TMR) for treating chronic pain resulting from limb amputation.
About 25 percent of all amputees develop chronic pain in the remaining portion of the amputated limb (phantom limb pain), making it difficult for some to wear prostheses, according to researchers from Northwestern Medicine in Chicago. The researchers said the pain doesn’t stem from the removed limb but rather is caused by a growth on damaged nerve endings.
“The problem is that the nerves that used to control the amputated limb are incomplete, but also remain active, constantly sending signals to the brain,” said lead study author Gregory A. Dumanian, MD, chief of plastic surgery at Northwestern Medicine, in a press release. “These separated nerves cannot heal properly without the chance to connect to other nerve tissue, and end up creating painful growths called neuromas.”
According to the researchers, the current standard of care for neuromas is not always successful and is geared toward reducing – not preventing – pain. They said that removing the neuroma and placing the nerve ending into a nearby muscle for cushioning allows the nerve to remain active and possibly form new neuromas. The TMR treatment prevents neuromas from reforming by surgically joining a damaged nerve to a healthy one so it can grow into and connect with the target muscle.
“Instead of trying to treat a painful neuroma by burying it, this procedure provides damaged nerves with a new purpose,” said Todd Kuiken, MD, PhD, director of the Center for Bionic Medicine at the Rehabilitation Institute of Chicago, and a professor of surgery at the Northwestern University Feinberg School of Medicine. “After TMR, patients can use these previously unable nerves to contract their target muscle and their repurposed signals can even be detected and used to control prostheses.”
The researchers are currently looking to enroll 200 participants for the four-year clinical trial. The lead site of the study will be Northwestern Memorial Hospital. Other participating sites will include Walter Reed National Military Medical Center, in Washington, D.C., the University of Washington Medical Center and Harborview Medical Center in Seattle, and the San Antonio Military Medical Center in Texas. Outcomes will be measured using an online pain questionnaire and magnetic resonance imaging of the nerves before and after surgery to compare TMR with standard surgical treatment for neuromas.
For more information, contact Dr. Dumanian at gdumania@nmh.org or Mona Shah, MD, atmrshah@nmh.org.