Why do some amputees feel phantom limb pain?
25 June 2016, 16:49
As reported in the British Journal of Anaesthesia, almost all amputees feel at least some sensations in the missing limb. At first, the phantom limb feels intact, even movable. While a few lucky patients merely feel mild tingling or sensations of heat or cold, 60 to 80 percent of amputees suffer actual pain.
Phantom limb pain sometimes mimics the pain that afflicted the limb before it was amputated.
In other cases, it creates new agony unlike anything a person has ever felt before. Some patients with the condition even feel as if the missing limb has been twisted or distorted into impossible positions.
For one Iraq war veteran whose leggs where blown off by an IED, Christian Bagge, the pain was severe. "On the pain scale of one to 10, I'd say it was a six or a seven," he says. "But then again, my '10' is getting both of my legs blown off."
It was only a couple of weeks after Christian Bagge came home from the war in Iraq that the torment began. Lying in his hospital bed at Brooke Army Medical Center in San Antonio, Bagge suddenly felt a crushing pain in his feet.
His feet, however, were not there.
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So what is phantom limb pain?
James Roper, M.D., is the chief of physical medicine and rehabilitation at the Birmingham Veterans Affairs Medical Center, where he has worked with hundreds of amputees over the years. "The most common description of phantom pain is that it's like a severe cramping, as if someone's foot is being crushed in a vise," says Roper.
"Other patients tell me it's like a red-hot, searing, burning, or a sharp shooting pain." Many times the brain seems to reproduce the pain the patient felt in that limb before it was amputated. "I'll have veterans tell me, 'It feels like when I first got shot,' " Roper says.
Phantom limb pain usually shows up within days of the amputation. However, some people first feel the pain years or even decades after losing a limb.
One patient, described in a 1999 issue of the journal Pain, felt new pain in a lower leg that hadn't existed for 44 years.
It's no wonder a report from the American Pain Foundation called the condition "one of the most mysterious forms of pain known in medicine."
But progress has been made. Not long ago, people with phantom limb pain were often told that they were either imagining things or going crazy. While many questions remain, there's no longer any doubt that phantom limb pain is a physical problem arising from the severed nerves that once connected the missing limb.
Here's a leading theory, as best researchers can explain it: The nerves remaining in the stump continue to send messages to the brain, and the brain scrambles to process the information. As explained by the American Pain Foundation, the brain has a hard time fathoming the loss of a limb, so it tries to re-create the limb using the nerve signals as a guide.
For reasons that nobody understands, the brain often translates those signals into pain. It's as if the brain needs strong, impossible-to-ignore reassurance that the limb still exists.
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Zeroing in on treatment
At this time, there is no single treatment for phantom limb pain. Doctors typically have to sort through many different possibilities to find the best approach for each individual patient.
"The experience of the pain is just as real as if the limb were still there," says Roper. "But the truth is, there isn't a very good explanation yet as to exactly what causes it."
According to reports from the American Pain Foundation, medications that calm nerves are a standard treatment. Options include anti-seizure drugs such as carbamazepine (Tegretol, Epitol) or tricyclic antidepressants such as amitriptyline. Some painkillers, including opioids and lidocaine, may also be effective.
Medications can be combined with alternative pain-relieving therapies, including transcutaneous electrical nerve stimulation (TENS), acupuncture, or biofeedback.
In another novel approach, researchers have used mirror therapy with some success to alleviate pain in amputated hands, arms, and feet.
Mirror therapy works by having a patient watch himself move his intact limb in a mirror, and positioning the mirror in such a way to give the appearance that the missing limb is still intact.
Most phantom sensations, including pain, tend to become less vivid over time. Many patients say that it feels like the phantom limb gradually shrinks.
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Mirror Therapy for Phantom Limb Pain. New England Journal of Medicine. Volume 357, Number 21. November 22, 2007. http://content.nejm.org/cgi/content/full/357/21/2206
Hanley, M.A. et al. Self-reported treatments for lower-limb phantom pain: descriptive findings. Archives of Physical Medicine and Rehabilitation. February 2006. 87(2): 270-277.
American Pain Foundation. Questions and answers: Phantom limb pain. February 2005. http://www.painfoundation.org/page.asp?file=QandA/Phantom.htm.
Cleveland Clinic Phantom Limb Pain. December 2004.
Harden et al. Biofeedback in the treatment of phantom limb pain: a time-series analysis. Applied Psychophysiology and Biofeedback. March 2005. 30(1): 83-93.
Interview with Christian Bagge, former Oregon National Guard member, Iraq war veteran, and amputee
Interview with James Roper, M.D., Chief of Physical Medicine and Rehabilitation at Birmingham Veterans Affairs Medical Center, Alabama.
Nikolajsen, L. and T.S. Jensen. Phantom limb pain. British Journal of Anaesthesia. 2001. 87(1): 107-116.
Rajbhandari, S.M. et al. Diabetic neuropathic pain in a leg amputed 44 years previously. Pain. 1999. 83: 627-629.