PHANTOM LIMB SYNDROME

It's called Phantom Limb Syndrome (PLS).

In 70 per cent of amputees, there's a continuation of sensation in the lost arm or leg. Some amputees even believe their lost limb still exists. When an amputation of an arm or a leg occurs, it's normally expected that the person will no longer feel sensation in the remaining stump. After all, when you have your appendix or tonsils removed, you don't expect to feel sensation in your abdomen or throat afterwards. PLS came to the attention of medical doctors in a major way when about 60,000 amputees returned from World War I. Originally it was called "hallucinated limb".

PLS was famously described in 1940 by Dr. S. Feldman of Cornell University in a classic article in the American Journal of Psychology. Among other things, Dr. Feldman pointed out that in double amputees, the sensations were often experienced in both missing limbs.

In 1992, writing in Scientific American, Dr. Ronald Melzack of McGill University in Montreal, claimed that PLS occurs in up to 70 per cent of amputees. The sensation has been described as often painful, cramping, or shooting. It can vary from occasional and mild to continuous and severe. Besides pain, the range of sensations can include pressure, warmth, cold, itchiness, and sweatiness. The sensations usually start soon after the amputation, but sometimes appear weeks, months, or years later.

Phantom limbs seem so lifelike to an amputee that some may attempt to step on a phantom leg and try to walk. When a person with a phantom leg stands up, the phantom leg seems to hang down. It unfolds and stretches out when its owner reclines. It bends properly when its owner sits. When walking, the phantom arm swings in perfect coordination. If a person had a tight ring on a finger or a painful bunion on the foot prior to the amputation of the arm or leg, the tightness is still felt after the amputation.

PLS can also afflict non-amputees. For example, the shoulder can be badly crushed in an accident such that the nerves serving the arm are ripped from the spinal cord. In such a case, the arm "experiences" no direct sensations, but the PLS may occur even though the limb remains attached. Surgical removal of the limb does not remove the phantom limb.

In cases involving paraplegics, where the spinal cord itself is severed, the limbs, genitals, and other body parts may become "phantoms". Phantom legs may seem to move, even to the point of physical exhaustion, and even though the person sees plainly that the legs are immobile. It is known that the area in the spinal cord assigned to relaying to the brain sensations from the genitals is located next to that of the feet. Thus, genital stimulation of people who have lost a foot sometimes triggers sensations in the phantom leg.

In one reported case, a man experienced orgasms in his phantom leg as well as in his genitals. In another case, by simply stroking a man who had lost one arm, the man reported two "virtual hands" which were "hidden in his face and shoulder". There are paralyzed people with PLS who cannot recognized that they are paralyzed. For example, if someone is paralyzed on their left side, even when they obviously fail to pick up objects with their left arm or cannot use their left arm to tie their shoes, they are emphatic that they are not paralyzed. A fascinating footnote to this is that when water is squirted into the left ear, many such PLS people are brought back to reality, lose their PLS sensations, and admit their paralysis, but only temporarily.

In PLS, it's almost as if the missing body part has a mind of its own. There are now three explanations of PLS. Dr. Melzack writes, "the oldest explanation for phantom limbs and their associated pain is that the remaining nerves in the stump, which grow at the cut end into nodules called neuromas, continue to generate impulses."

However, in cases where the interior nerve fibres leading from the neuromas to the spinal cord have been surgically cut, the PLS sensations either do not disappear or disappear temporarily, only to return after a few weeks or months. Thus, the neuromas are not the source of the sensations. The second explanation is that the source of the sensations lies somewhere in the spinal cord itself. Thus, the spinal cord sends strange signals to the brain. But no evidence of such a mechanism has been found. The final, most recent, and probably best explanation is that the brain itself is the source of the sensations.

In PLS, somewhere in the vast network of the brain's millions of neurons a charade is taking place. This view is put forward by Dr. V.S. Ramachandran from the University of California at San Diego in Phantoms In The Brain (William Morrow, 1998). Dr. Ramachandran contends that "when the area of the brain assigned to the lost limb no longer receives sensory input from the area, it begins to react to sensory input arriving at adjoining areas in the brain. In other words, the idle area overhears nearby signals that are being processed and acts upon them in error."

What is the lesson in all of this?

PLS demonstrates that the brain fights to restore normality after the body is mutilated through injury. We do not fully understand the origins of all human sensations.

There is much to discover about who and what we are.

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