Phantom pain – the sensation some amputees experience in the portion of the limb that has been removed – is experienced by as many as 80 percent of amputees worldwide, according to the Amputee Coalition.
Phantom pain can be nearly constant, or felt in short, intense bursts. It has many descriptors including sensations of warmth, coldness, tingling, cramping, constricting, shooting, stabbing, squeezing, throbbing, or burning. It can be triggered by a variety of things, but common causes include stress, inactivity, and sensations caused by internal organs performing common bodily functions.
There are many theories why phantom limb pain is so common. Some theories have to do with how nerves, vision, and the brain work together. Other theories have to do with memory.
While amputation removes visual and proprioceptive inputs, the neurons or nerve cells leading to the limb are still intact and continue to send signals. When they don’t get a response, they keep sending stronger signals to the missing limb. The brain interprets the lack of signals coming back as a mismatch of signals, creating a phantom sensation that an amputee can feel.
The first step to combating phantom pain is for the amputee to inform his physician, who may first try to relieve the pain with medications including antidepressants, which work by modifying chemical messengers that relay pain signals.
Other medication options include anticonvulsants, which work by quieting damaged nerves to slow or prevent uncontrolled pain signals, and narcotics, such as codeine and morphine, which can be addictive and cause side effects.
In addition to medication, which is not always a successful treatment for many amputees, there are noninvasive therapies (TENS, acupuncture) and invasive therapies (injections and spinal cord stimulation).
In TENS (Transcutaneous Electrical Nerve Stimulation) the user has a battery pack with electrodes, which are then attached to the skin to transmit a mild electrical current. Constant low-level electrical stimulation through the skin overrides pain nerve fibers. The intensity can be controlled so the person received constant stimulation, pulsations or intermittent bursts.
The National Institute of Health has found that acupuncture – placing needles at certain points on the body – can help with some types of chronic pain. Acupuncture stimulates the central nervous system to release the body’s natural pain-relieving endorphins.
Minimally-invasive therapies involve injecting anesthetics, steroids or both directly in the residual limb, and spinal cord stimulation, where the physicians inserts tiny electrodes along the spinal cord, to stimulate nerve in the spinal cord. This interferes with the impulses traveling toward the brain and lessens the phantom limb pain.
Another method is mirror box therapy, where a patient sees his sound limb in the mirror. The mirror tricks the brain into thinking that the missing limb is still there, resulting in a significant therapeutic response. For many patients, the phantom limb pain resolves or the intensity of the pain decreases.
It’s important to note that any therapies should first be discussed with your physician, as underlying medical conditions can be affected by drugs, acupuncture, TENS, etc.
Keeping the residual limb healthy and pain-free may help reduce the onset of phantom pain. Exercises can help maintain muscle tone in the residual limb, as well as stretching, gentle massage, and using an ace wrap.
It’s also important to make sure the prosthesis is not causing additional discomfort. For the best possible fit, it’s important to have it routinely checked by the prosthetist, especially if there are changes in activity level, weight gain or loss, and any changes in overall health.