Medical Author: Standiford Helm II, MD
Medical Editor: Melissa Conrad Stöppler, MD
Jack Tsao, M.D., is a physician who has studied the use of mirrors to treat phantom limb pain in Iraq war veterans. Phantom limb pain refers to pain felt in the area in which a limb has been amputated, and it may range in intensity from very mild to severe and debilitating. It occurs because the nerve endings at the site of amputation send messages to the brain and trick the brain into believing that the amputated limb is still present.
Dr. Tsao's mirror technique is simple. The patient sits with a mirror facing the remaining leg, moves the remaining leg and watches the reflection in the mirror, so that it appears that both the good and the amputated leg are moving. Dr. Tsao has found that by using this technique, he is able to decrease opioid use, decrease painful phantom pain sensations, and help the wounded veterans return to work.
It is not obvious why this simple technique works. Observations of events help us develop new theories to explain why events happen. Ronald Melzack, PhD, famed for inventing the gate theory of pain, recently proposed a unifying theory of self-perception and pain which provides some insight into how Dr. Tsao's technique works. Basically, Dr. Melzack points out that what we feel, whether pain or not, comes from the brain. Phantom limb pain shows that while what we feel can be influenced and modulated by input from the body, the brain's processes can act in the absence of any such input. Thus, everything we experience lies in neural networks in the brain. This is a hard-wired, genetic process. Melzack hypotheses that the shooting phantom pains that Dr. Tsao's patients felt are caused by the brain attempting to move the absent limb, sending out abnormal neural patterns which are experienced as shooting pain.
Using traditional techniques, only about 10%-12% of amputees have any relief from phantom limb pain. Dr. Tsao's approach, therefore, represents a potentially major breakthrough. Why it works remains an open question. The body continues to get abnormal information from the amputated limb. It is not obvious why looking at the remaining limb moving in a mirror would cause the body's image of the amputated limb to change.
What is important is that this technique does hold the promise of an effective treatment to an otherwise debilitating, refractory problem. In addition, we may get a better understanding of how pain is perceived and how consciousness exists because of this information.
Reference: Melzack R. Evolution of the Neuromatrix Theory of Pain. The Prithvi Raj Lecture: Presented at the Third World Congress of World Institute of Pain, Barcelona 2004. Pain Practice 2005;5:85-94. www.cnn.com, "For amputees, an unlikely painkiller: Mirrors," by Saundra Young, March 19, 2008