Tuesday, June 9, 2009
Understanding phantom limb pain
By Louis Neipris, M.D., Staff Writer, myOptumHealth
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Foot pain so bad it awakens a deep sleeper. Hand pain so severe it feels like it's in a vise grip. What's unusual about these complaints is that they can come from people whose foot or hand was amputated. But how can something that's not there hurt so badly? This type of pain is called phantom limb pain. It adds to the difficult experience of adjusting to life after injury. Forty percent to 80 percent of people who undergo amputation have some degree of phantom limb pain. To many of the soldiers with traumatic amputations, phantom limb pain can make rehabilitation even more challenging.
Phantom limb pain is different from residual limb pain, which is pain in the remaining limb or stump. Phantom limb pain is also distinct from phantom limb sensation, non-painful sensations in the missing limb. While it's annoying or distracting, phantom limb sensation is not debilitating.
The pain often starts within days after the loss of the limb. For some, though, phantom limb pain doesn't appear until months or even years after losing the limb. In most cases, the painful attacks will become shorter and less frequent as time goes on.
People were once told they were imagining the pain or that it was a psychological problem. Now there is a better understanding of why phantom pain occurs. This offers greater hope for successful treatment.
What are the symptoms of phantom limb pain?
Pain in the missing part of limb
Squeezing, like missing foot or hand is being crushed in a vise
Sensation that missing limb is twisted or distorted
Burning, tingling, throbbing, shooting pain, pins and needles sensation, stabbing, pinching or cramping
Symptoms tend to get worse in cold weather or before a storm. Stress or anxiety can also worsen phantom limb pain. So can pressure caused by a prosthesis.
What causes phantom limb pain?
The exact cause is not known. Imaging studies done during symptoms show that there is activity in the part of the brain that previously controlled the missing limb. It may be the brain's attempt to process information from the damaged nerves. The resulting sensation is pain.
How is phantom limb pain diagnosed?
The diagnosis is made on the basis of a history and physical exam. It is important to give the doctor all details, even if they sound strange. Your doctor will look at the stump for any painful spots that can trigger phantom limb pain. If you have a prosthesis, the doctor will also make sure it fits properly. A poor-fitting prosthesis can trigger phantom limb pain.
Finding the right treatment for phantom limb pain is challenging and can take time. Treatment may include:
Medications used to treat epilepsy and depression may also help relieve phantom limb pain. Your doctor may also prescribe opioids (a type of pain killer). Other medicines such as beta-blockers or anti-inflammatory medications may help, but more studies are needed to test how well they work for this. It may take time to find which medicine is best for you.
Transcutaneous electrical nerve stimulation (TENS). This is electrical stimulation of the skin around the stump to attempt to interfere with nearby painful stimuli. TENS therapy is an effective treatment for many with phantom limb pain.
Other treatments may include different forms of physical medicine, including biofeedback. The goal of biofeedback is to use visual or other sensory stimuli to retrain the brain to stop sending pain signals. Sensory discrimination training is another therapy that has shown promise in helping with the pain.
Relaxation techniques, such as visual imagery, have been shown to help in some other types of pain. But more research needs to be done using these techniques in phantom limb pain.
Nerve blocks or epidural blocks are sometimes used when the pain cannot be relieved with other methods.
Rarely, surgery may be an option when the pain can't be controlled. Spinal cord stimulation or disruption of the nerves that carry pain messages have been tried in a few cases of pain that did not respond to any other treatments.
Team approach and support
For many, a combination of medical, behavioral and social support is the best approach. Losing a limb is a major life-altering event. Sharing your feelings with others going through similar experiences can often help. Work with a team that includes a pain management specialist, psychologist and both a physical and occupational therapist. A social worker can help you coordinate these services.
Amputee Coalition of America. Pain management. Post amputation pain.
American Pain Foundation. Pain question and answer: Phantom limb pain.
Birklein F, Maihöfner C. Use your imagination. Training the brain and not the body to improve chronic pain and restore function. Graded motor imagery. Neurology. 2006;67(12):2115-2116.
Moon SB, Se HJ. Phantom Limb Pain. In: Frontera WR, Silver JK, Rizzo TD. Frontera: Essentials of Physical Medicine and Rehabilitation, 2nd ed. Philadelphia, PA: Saunders Elsevier; 2008.