“Pain may also be caused by a mismatch of visual signals and proprioception. Pain signals continue to come into the brain, but the eyes tell the brain the limb is gone. The brain creates a phantom limb to explain the mismatch,” he added.

Treating Phantom Limb Pain

“Phantom limb pain is considered to be neuropathic pain, so it is often treated with drugs used for other neuropathic pain. There is some evidence that pain present in a limb before amputation increases the risk and severity of phantom pain after amputation. One form of treatment is to use nerve blocks before and after amputation,” said McGowan.


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This treatment is called preemptive analgesia. One study found reduced pain at six months when preemptive analgesia was used 48 hours before and after amputation.1

Drugs that may be used to treat phantom limb pain include NSAIDs, opioids, antidepressants, and anticonvulsants.

“None of these are universally successful. Opioids can help but need to be used carefully. Interventions can include stellate or lumbar nerve blocks, spinal cord stimulation, and some people have even tried deep brain stimulation, but there is little evidence to support any one of these interventions,” said McGowan.

Scattered reports suggest relief from using acupuncture, biofeedback, hypnosis, cognitive behavioral therapy, and guided relaxation, but there have been no large studies to support any of these.

Mirror Therapy

One therapy that has been supported by randomized controlled studies is mirror therapy.3 “Pharmacologic therapies are hit or miss for symptom control. We have had success in about 60 to 90% of our patients using 15 to 20 minutes of mirror therapy five times per week for several weeks,” said Tsao.

Mirror therapy is simply the visual feedback of watching a limb moving. It may work by resolving the visual-proprioception mismatch caused by limb loss. The patient watches a mirror image of a moving limb, usually their own, while they imagine moving their absent limb.

“The improvement seems to be driven by vision, suggesting that visualization is more powerful than touch or proprioception and can override painful signals,” said Tsao.

One problem with amputee vets is that about 30% of combat amputees have lost both legs. Because most mirror therapy is done by watching a mirror image of a remaining leg, Tsao and his team at Walter Reed National Military Medical Center designed a study to see if observing another person’s limb movements could also relieve phantom limb pain.

The 2014 study was published in the Annals of Clinical and Translational Neurology. Twenty bilateral lower limb amputees were assigned to either visual or mental observation.

The 11 people assigned to the visual observation group were trained to imagine movements of their lower limbs while watching an experimenter’s limbs making the same movements. Amputees in the mental observation group just closed their eyes and imagined moving their legs.

After 20 minutes of daily therapy lasting one month, direct visual observation resulted in significant pain reduction in 73% of the amputees. The mental imaging group got no pain relief.3

“Visual observation therapy is low-cost, simple, and effective. Virtual reality systems may be used to get this same effect, but they are more expensive and require trained technicians,” said Tsao.

Phantom limb pain is a common and sometimes disabling complication of amputation, and the etiology is just starting to be understood. Mirror therapy may offer a simple and inexpensive option to medications and other interventions that may have unwanted side effects and unpredictable results.

Chris Iliades, MD, is a full-time freelance writer based in Cape Cod, Massachusetts. This article was medically reviewed by Pat F. Bass III, MD, MS, MPH.

References

  1. Subedi B et al. “Phantom limb pain: mechanisms and treatment approaches.” Pain Res Treat. 2011; doi:10.1155/2011/864605.
  2. MacIver K et al. “Phantom limb pain, cortical reorganization and therapeutic effect of mental imagery.” Brain. 2008; doi:10.1093/brain/awn124
  3. Tung ML et al. “Observation of limb movements reduces phantom limb pain in bilateral amputees.” Ann Clin Transl Neurol. 2014; 1(9):633-638.