Phantom Limb Syndrome

Phantom Limb Syndrome is the name given to the feeling experienced by amputees and wherein the person's brain occasionally still receives messages from the lost limb, and therefore the amputee may feel a wide variety of perceived nerve responses from removed limb. These perceptions of feeling may include tingling, itching, and mild to severe pain. Fewer than 6% of amputees never experience the sensation of still having some feeling in their missing appendage(s).

Vilayanur Ramachandran is a neuroscientist and university scholar who has done a large amount of research into the area of phantom limb syndrome. The cases he has studied and documented range from the mundane to the completely bizarre. He discovered that limbs which had been paralyzed prior to amputation might continue to seem so to the amputee, even in the limb's phantom state. He found this could occur to the point of causing a patient pain similar to that of having held a limb in an awkward position for too long, as would occur with a paralyzed arm in a sling, for example.

One of the things that he has found in his research is that the brain codes nerves into "maps" of information and that the mind may "remap" the nerves of the body when a limb is removed, also known as "cortical reorganization". When this occurs, tactile sensations on existing body parts may actually stimulate corresponding feelings of tactile sensations on specific areas of a missing appendage. Brushing a person's chin may cause that person to feel a missing pinky is being stroked, and so on. It also would appear that there is a somewhat predictable pattern to where sensations are remapped, rather than a random reassignment. Nerve information for lower legs, for instance, is generally remapped onto the genital area, such that a person with a missing lower shin may feel sensations in this part of their body during intercourse.

Surprisingly, however, Phantom Limb Syndrome may also occur in those people who were born with missing limbs or digits. A patient with no lower arm may report feeling pain the in hand when the ulnar nerve on the "funny bone" is struck, which is a feeling common in amputees as well. A person born with only one hand or foot may, at least in dreams, have the sensation of both hands. This would seem to indicate that, contrary to earlier theories, the brain develops the neurons to feel a limb even if they do not develop the limb itself.

To a much smaller degree, research also has been conducted into the phantom limb phenomenon as it affects those with reattached limbs or patients who have experienced the rare procedure where a limb has been cross transferred from one side of the body to the other.

Sources:

Phantom Limbs: Sensations When There Should be None, Tina Chen http://serendip.brynmawr.edu/bb/neuro/neuro02/web2/tchen.html

Phantom Limb Phenomenon After Limb Reattachment or Cross-Transfer,

Three Patient Histories, Douglas B. Price, M.D. http://psy.psychiatryonline.org/cgi/content/full/39/4/384

Definition of Phantom limb syndrome http://www.medterms.com/script/main/art.asp?articlekey=9113

Nova, From Ramachandran's Notebook http://www.pbs.org/wgbh/nova/mind/note_nf.html