Phantom Limbs: The Science of Impossible Sensation Part 1
The strange truth about phantom limbs
Posted Jun 15, 2019
By Alexander Metz
We have always been obsessed with the phantasmagorical. Almost every culture on Earth has some conception of ghosts, ghouls, spirits, and specters. Charles Dickens wrote about apparitions in A Christmas Carol and “The Signal-Man,” Shakespeare in Hamlet and Macbeth. The notion of the phantom is at once comforting and chilling. It gives us solace to believe that what departs the earthly realm is not gone, but merely transmuted. And that we might someday be reunited. On the other hand, seeing the dead resurrected fills us with terror. It is unknown, unnatural, and horrifying.
A Most Unusual Feeling
We would like to believe that ghosts are confined to the realm of fiction. However, for many amputees, the “phantom limb” is a strange reality both mysterious and burdensome. Phantom sensation has been well documented. The British admiral Horatio Nelson, after losing his arm in 1797, reported feeling the nails of his clenched fist digging into his hand. This despite the fact that both his hand and arm were no longer there. Nelson believed this to be conclusive evidence for the existence of the human soul.
Another, more recent, example comes from a letter to the editor published in The New York Review of Books. Erna Otten recounts that her piano teacher, Paul Wittgenstein, an amputee from the first World War, “told me many times that I should trust his choice of fingering because he felt every finger of his right hand.” Wittgenstein had no right hand, but he still felt it with perfect clarity, years after it had been removed.
The Phantom Limb
Almost all amputees will experience phantom sensation at one time or another. A phantom limb can manifest in many different ways. Some patients feel as if they can move their arm just as easily as they had before the amputation. Others, however, feel as if the arm is paralyzed: a dead weight. Phantoms have even been reported in patients who lack limbs as a result of a congenital disability.
Distinct, though closely linked to phantom limb syndrome, which is non-painful, is phantom limb pain. Patients describe pain in their limbs as anything from burning, cramping, or stabbing to an intense muscle contraction they are unable to release. Both the duration and intensity of the pain are highly variable. One commonality, however, is that the pain is often difficult to remedy.
How is it possible to feel pain in a limb that's not there? We commonly understand feeling to be the result of signals from the tissue interpreted by the brain. Nerve cells in the skin can tell if something is hot, cold, rough, smooth, sharp, or dull. If there is no tissue, there ought to be no feeling. How then could Mr. Wittgenstein feel a hand that was no longer attached to him? Moreover, how could he feel it, not as a vague object stuck to the end of his arm, but as the delicate and refined hand of a master pianist?
Early Clinical Study
Human beings, particularly ones that have been through something traumatic, develop all manner of coping mechanisms, including denial or delusion. For this reason, it was generally thought that amputees imagined their phantom sensation. The fact that phantom limb sometimes fades with time also seems to support the delusion hypothesis: Patients are getting over it or coming to their senses. It was easier for doctors to say their patients were hallucinating than it was to give an account of how someone could genuinely be feeling something that wasn’t there. The illusory nature of phantom sensation relegated it, for the most part, to the realm of mere medical curiosity.
In 1872, Silas Weir Mitchell, the doctor who coined the term “phantom limb,” began to suggest that the syndrome was not psychosomatic. He noted the remarkable certainty with which amputees described their phantom motions. Delusion did not explain the extreme prevalence of both phantom limb syndrome and phantom limb pain. It also does not explain the experience of phantom feeling in patients who never had that limb to begin with, or, in the case of Mr. Wittgenstein, why his fingerings were always so precise.
Still, though, doctors had no idea what might cause phantom limb. Nor did they have any method of treating it. For a time, it was thought that the pain might stem from the nerve endings at the end of the patients' “stump.” However, subsequent surgeries to remove more of the patients' limbs generally did not affect pain or sensation.
In addition to the phantom itself, patients who feel their missing limb sometimes experience several other strange phenomena:
Telescoping, which generally presents in cases of amputated arms, is when the phantom collapses like a spyglass, shortening the distance between the end of the limb and the body. When this happens, the phantom hand or fingers seem to be attached directly to the remaining portion of the arm or shoulder. Stranger still, patients occasionally have control over the telescoping, allowing them to “extend” or “retract” their phantom at will.
Phantoms also sometimes retain “memories.” Patients who previously wore wedding rings before amputation commonly report still being able to feel the ring on their phantom. One patient even stated that her phantom could sense changes in the weather, because prior to her amputation, her arthritic joints had been sensitive to changes in humidity. In addition, phantoms sometimes "stick" in the last position they occupied before removal—for instance, patients feeling as if their arms are still in the sling they wore leading up to the operation. This type of memory also seems to be positively associated with trauma. For example, a soldier whose hand was blown off by a grenade felt as if he was still clutching it.
Another strange clinical phenomenon is when amputees report feeling sensation in their phantoms when another part of their body (usually the face) is stimulated. In one study, when a cotton ball was moved systematically around the patients' face, they reported feeling the cotton ball both on their face, and on their phantom hand. What is yet more illustrative is that the regions of the face which corresponded to the sensations in the various fingers were both “non-random,” meaning they were broadly the same across all patients who exhibited the phenomena, and “clearly defined,” meaning that patients reported very precisely the movement from one area to another.
Guenther, K. (2016). 'It's all done with mirrors': V.S. ramachandran and the material culture of phantom limb research. Medical History, 60(3), 342-358. doi:10.1017/mdh.2016.27
Ramachandran, V. S., & Hirstein, W. (1998). The perception of phantom limbs: The D. O. hebb lecture. Brain, 121(9), 1603–1630.
Sacks, O., & Otten, E. (1992). Phantom limbs. Retrieved from https://www.nybooks.com/articles/1992/01/30/phantom-limbs/