Phantom Limbs

Phantom Limbs

Phantom Limb Pain (PLP) is a serious condition that occurs when a person who has lost a part of their body though amputation, trauma (brachial plexus), or loss of nervous connections in an appendage, perceives that the limb is still there and experiences sensations coming from this area. It was first described in 1866 by S. Weir Mitchell, an American neurologist, through a short story published in Atlantic Monthly. While Mitchell may then have wondered if this was specific to wounded Civil War soldiers, it has since been established as quite common (1). Over 70% of amputees report phantom limb pain for years after amputation (2). Several theories have been proposed regarding PLP, although there is still much to be learned and understood. Early physicians believed that phantom limb sensations were caused by severed nerves that fired randomly, sending signals to the somatosensory cortex re-creating sensations seemingly coming from the missing limb. However, this theory was soon disproved when surgeons tried unsuccessfully to eradicate these sensations by cutting the nerves leading to the neuromas, preventing the neuromal signals from reaching the cortex. Researchers then began to concentrate on the role of the spinal cord in PLP, but realized that paraplegics with completely severed spinal cords still experienced sensations where their limbs had been (5). Focus then turned to the brain and its role.

Until the mid 1980's, it was widely believed that once neural pathways were placed during fetal development, these pathways did not change and were not altered in any recognizable way (3). However, recent studies have shown that the brain has a high degree of plasticity into adulthood, which allows it to continuall...

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...opens the doors to looking at the neuromatrix and corollary discharge signals in the brain and the influence that these prewired expectations may have on the body, especially pain. These ideas are the key to providing long-term pain management for PLP patients.

Works Cited:

1. Yang, Tony T., Gallen C., Schwartz, B., Bloom, F.E., Ramachandran, S. Cobb, "Sensory Maps in the Human Brain," Nature, vol. 368, 14 April 1994: 592-593.

http://zygote.swarthmore.edu/axon6.html

2. Flor, H., Elbert,T., Knecht, S., Wienbruch, C., Pantev, C., Birbaumer, N., Larbig, W., Taub, E., "Phantom Limb Pain as a Perceptual Correlate of Cortical Reorganization Following Arm Amputation," Nature, vol. 375, 8 June 1995: 482-483.

http://www.bfe.org/protocol/pro05eng.htm

3. Grobstein, Paul, Class Lecture. Neurobiology and Behavior. Bryn Mawr College. February and April 1998.