The effect of phantom pain, in which a person feels an amputated or paralyzed limb, has been known to medicine since the Middle Ages. However, the mechanism of these sensations was hidden from doctors for a long time. The answer to the phenomenon was discovered by Swiss scientists
Doctors investigated several cases known as "excess phantom limb." This syndrome occurs when phantom sensations are accompanied by the patient's confidence that he is able to perform the full range of actions with the help of a paralyzed limb.
A painless phantom
Many patients continue to experience the phantom limb immediately after the amputation of an arm or leg (Simmel, 1956). A phantom limb is usually described as having the same shape and characteristics as a real limb prior to amputation. There is a feeling that the phantom limb occupies the same position in space as the real one would take when the patient walks, sits down, goes to bed. Initially, it feels normal in size and shape, the amputee tries to grab the object with his missing hand, gets out of bed on the missing leg. Over time, however, the phantom limb changes shape, may take an unnatural, pretentious position in space, become less distinct, or may disappear completely.
Amputation of a limb is not the only condition in which a phantom occurs. A painless phantom is often described by patients with a local block of sensitivity in any part of the body. As was described by Simmel (1962) in patients with spinal cord injury, Melzack and Bromage (1973) in patients with brachial plexus injury. With a block of the brachial plexus in the phantom hand, severe itching, tingling is felt, the patient especially clearly feels the position of the hand and fingers in space. When the patient looks at the real hand, the position of which is different from the phantom, both images immediately merge. With closed eyes, the phantom takes the previous position (Melzack and Bromage, 1973,! 974). This suggests that the existence of the phantom is due to the activity of the centers of the cerebral cortex responsible for the body schema. In the absence of afferent impulses coming from receptors of the skin, muscles, joints (and in the absence of visual control), the perception of position in space can differ significantly from the real one.
Painful phantom
The difference between a painless and painful phantom is not great. Some amputees have very mild or rare pain. Others suffer from intermittent pain, ranging from several attacks a day to 1 to 2 times a week. The rest are subject to constant pain, varying in intensity and quality. By the nature of the described pain can be divided into 3 groups: with a predominance of "causalgic" (burning, scorching), with a predominance of "neuralgic" pain (similar to an electric shock) and pain of the "crumpy" type (constricting, squeezing). They can begin immediately after amputation, and sometimes occur weeks, months, or even years later. Pain may be felt in a specific part of the phantom limb (Lingston, 1943). So, for example, patients complain that the phantom hand is clenched into a fist, fingers are drawn together, dig into the palm,from which the brush gets tired and sore.
If pain persists for a long enough time, other parts of the body are sensitized, and simple touching them causes spasm and intense pain in the phantom limb (Croncholm, 1951). Pain is also often triggered by visceral impulses, such as during urination and defecation (Henderson and Smyth, 1948). Even emotional experiences, stress can cause increased pain. At the same time, surgical interventions, such as neuro-, radiculo-, sympathicotomy and others, are often unsuccessful, and the patient can undergo a number of operations without a significant decrease in the intensity of pain.
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Properties of phantom pain
Phantom limb pains are characterized by 4 main properties:
- The pain continues after the damaged tissue has healed. In some patients, pain is transient, while in others it persists for years or decades (Sunderland, 1978), even when the original injury is completely healed. Sometimes the pain is similar to that which preceded the amputation (Bailey and Moerch 1941, White and Sweet 1969). So, for example, a patient who injured his finger with a chip that bounced off a tree, and subsequently lost his arm as a result of an accident, complained of pain in his finger, exactly the same as from a chip that had sunk in the past. Similarly, patients with an amputated leg feel pain in it from ulcers that existed in a real leg before its surgical removal. Within two years after amputation, 45% of patients feel pain in one specific location, and 35% of patients feel the same pain as on the eve of amputation (Jensen et al., 1985).
- Trigger zones can extend to healthy areas on the same or opposite side of the body (Cronholm, 1951). A light touch on the other limb or on the head can trigger an attack of severe pain in the phantom limb. Obviously, pain away from the stump can cause phantom pain. For example, angina pectoris that develops within 25 years after amputation can provoke severe pain in the phantom limb with each attack.
- Long-term pain relief can be achieved by reducing somatic impulses. This is the basis for treatments such as the local injection of anesthetics into sensitive areas or nerves in the stump. These blockages can stop pain for hours, days, weeks, even forever, but are usually only effective for a few hours (Livingston, 1943).
- In addition, increased sensory impulses can provide long-term pain relief. Injection of a hypertonic solution into the appropriate areas causes pain radiating to the phantom limb, lasting about ten minutes, followed by dramatic partial or complete disappearance of pain for hours, weeks or forever. Vibration stimulation, electrical stimulation of the stump muscles can also provide relief. Surgically, electrodes can also be placed on the spinal cord.
One patient, whose left arm was paralyzed after a stroke, regularly feels ghostly activity. For example, it seems to her that she can correct her hair with her left hand and even feels her touch with her scalp.
By comparing the activity of the brain when working with both hands - the real right and the illusory left - the scientists were able to determine the part of the brain responsible for creating phantom limbs. At the same time, in both cases, excitation of those regions of the left and right hemispheres, respectively, which are responsible for motor functions, stimulation, and visual orientation, was observed.
The discovery leads immediately to several conclusions that can change the modern understanding of rehabilitation medicine and neurology. First, it became known that all limb control functions remain in the human brain after stroke-related paralysis. Perhaps this will allow in the future to develop a methodology for the rehabilitation of patients, which will give them the opportunity to control their body again.
Second, a series of studies have shown that the human brain is unable to adapt to the effects of trauma for a long time. Some subjects have been experiencing phantom pain for several decades, and their nervous system is still trying to operate on paralyzed limbs.
The experiments of Swiss doctors touch upon another interesting scientific topic - the experience of the body, which describes the mechanical memorization of a certain set of movements by a person. We rarely control a series of daily actions, and it is the brain's ability to remember and reproduce these actions that has become the focus of scientists' attention.
Along with this, patients described their feelings as observing themselves from the outside. A similar phenomenon, known as "autoscopy", often occurs with overwork and a number of mental disorders. But, despite the halo of mysticism surrounding this phenomenon, scientists are confident that phantom sensations are part of autoscopy and will allow a better study of this unusual condition.
