Surgical technique drastically reduces pain for amputee cancer patients
When Annette Rios was diagnosed with chondrosarcoma, a type of bone cancer, doctors told her they’d need to amputate her right leg just below the knee.
“The cancer had formed in the small bones of my heel,” Annette said, “and the doctors told me amputation was the most effective way to remove the tumor along with any cancer cells that may have spread.”
The surgery, while necessary, also came with a drawback known as phantom limb pain. This occurs when pain seems to be coming from the part of the limb that’s no longer there. Although the limb is gone, the severed nerve endings continue to send pain signals to the brain, causing it to believe the limb is still there.
Phantom limb pain common after amputation
Phantom limb pain can feel like burning, twisting, itching or pressure. It affects 70% to 90% of people who undergo amputations. Another 50% will have chronic pain in the remaining part of the limb. This pain is especially challenging for amputee patients who use prosthetic limbs.
“Relearning how to perform simple tasks with a prosthesis takes time and patience,” says plastic surgeon Margaret Roubaud, M.D. “This can be nearly impossible due to constant pain caused by severed nerves.”
But an innovative surgical technique is reducing and sometimes even eliminating pain. It’s also giving amputees more control over their prosthesis. The technique, known as targeted muscle reinnervation (TMR), increases their independence and quality of life.
Bringing targeted muscle reinnervation to MD Anderson
Roubaud became interested in targeted muscle reinnervation when the Department of Defense started offering free courses on the technique, encouraging surgeons to learn a method that would drastically improve amputees’ pain. Recognizing how valuable targeted muscle reinnervation could be for MD Anderson patients, she took the course.
Targeted muscle reinnervation was initially developed in the early 2000s to help wounded veterans or amputees get more advanced types of prostheses. Funding from the defense department allowed the developers of TMR to conduct a randomized clinical trial, in which some amputees received the procedure and others did not. Surprisingly, they found that the patients who received targeted muscle reinnervation had much less pain after surgery – so much so that the trial ended because it was deemed unethical to not provide the procedure to all patients.
Retraining the brain to break the cycle of chronic pain
Before targeted muscle reinnervation came along, surgeons simply “buried” nerves cut during an amputation deep into a muscle or bone. This often created a cycle of chronic pain.
But TMR reroutes these severed nerves and connects them to nerve branches in nearby muscles that no longer perform a useful function because of the amputation.
This creates new neural connections and gives those signals emitted from the disconnected nerves something to do and somewhere to go, other than as pain signals to the brain. The brain is “retrained” to read feedback signals from new muscle connections and no longer searches for the amputated limb. Phantom limb pain lessens or disappears altogether.
Non-narcotic pain management
The surgery takes about an hour, and can be done during an amputation or as a separate surgery, after an amputation has already taken place. Patients still receive the same pain medication and physical therapy after surgery as those who undergo a traditional amputation.
“Targeted muscle reinnervation can be especially beneficial for cancer patients, because many have undergone chemotherapy and radiation and are experiencing pain from the cancer itself,” says Roubaud, whose research on reinnervation was recently published in the Journal of Surgical Oncology.
“Pain before surgery increases the likelihood of pain after surgery. TMR is a non-narcotic, non-opioid way to handle pain, and given the current opioid crisis, that’s a big deal,” she says. “There have never been reported cases of targeted muscle reinnervation making pain worse, so the procedure has virtually no disadvantages.”
Getting patients back to an active lifestyle
Annette opted for targeted muscle reinnervation, since staying active was very important to her. With an 11-month-old daughter, she couldn’t slow down.
“Getting back on my feet was one of my biggest goals,” she says. “As a medical assistant, I’ve cared for amputee patients and knew what I was going into. After surgery, I had no debilitating pain, and I still don’t.”
Annette received her prosthetic limb and went back to nursing school less than three months after surgery. She graduated this year.
“I’m not sure I could have done all this without targeted muscle reinnervation,” she says. “My care team helped me understand my options. Preventing that nerve pain has been one of the best decisions I’ve ever made.”
Roubaud has performed targeted muscle reinnervation on 29 patients so far. All have reported substantially decreased pain. She’s training other MD Anderson plastic surgeons how to perform the procedure so it’s more widely available.
“In addition to reducing pain, we hope this technique will improve prosthetic control. Many of our upper-extremity amputees opt not to use a prosthesis because they are awkward and don’t provide a significant functional advantage,” he says. “Improved prosthetic control could significantly enhance their quality of life.”