History and Neurology of Phantom Limb Pain
In the 1950’s Canadian neurosurgeon, Wilder Penfield, demonstrated areas of the brain that map out bodily sensation and perception in the parietal lobes. A schematic model of these areas representations became known as the Penfield Homunculus.
In 1986, Wain tested the efficiency of hypnosis in treating phantom limb pain. One pertinent finding was the ability of effective hypnosis in teaching the patient the ability to regain control over their difficulty.
In 1990, researchers Arena, Sherman, Bruno and Smith demonstrated a significant relationship between stress and limb pain, with each affecting the other in a recursive relationship. One recommendation is that of psychophysiological interventions to interrupt this relationship.
In his groundbreaking book, “Phantoms In The Brain” V. S. Ramachandran demonstrates how the brain “remaps” the missing limb to sensory areas adjacent on the sensory cortex in the parietal lobe. For example, with one patient he describes how the phantom hand is remapped onto the corresponding cheek. Curiously, sensations felt in the cheek are also felt in the phantom hand.
These remapped sensations are “sensory-specific” meaning that a drop of water on the cheek is felt like a drop of water on the hand, hot and cold also felt the same way.
The remapping is precise enough that areas of the sensation of specific areas of the phantom hand can be drawn on the corresponding cheek.
Other remapping occurs. For example, the genitals and feet are next to each other on the sensory cortex of the brain. Thus it is sometimes reported that lower leg amputees experience orgasmic sensations in their phantom foot. In these instances, orgasm can be felt as being more intense since it is mapped over a larger area of the brain.
Virtually any amputated body part can be experienced as a phantom. For example, phantom breasts, noses and penises have been reported.
Other possible causes (influences?) of phantom pain include inflamed neuromas in the stump region and/or scar tissue in the stump.
The term “neuroplasticity” described the brain’s ability to remap function (for example, in the case of someone learning sign language following total hearing loss, the visual cortex takes over much of the language function). Research into the speed by which phantom limb pain occurs suggests neuroplasticity is far greater than previously believed.