Is phantom pain experienced by amputees neurological?
1918041#7
The neurological basis and mechanisms for phantom limb pain are all derived from experimental theories and observations. Little is known about the true mechanism causing phantom pains, and many theories highly overlap. Historically, phantom pains were thought to originate from neuromas located at the stump tip. Traumatic neuromas, or non-tumor nerve injuries, often arise from surgeries and result from the abnormal growth of injured nerve fibers. Although stump neuromas contribute to phantom pains, they are not the sole cause. This is because patients with congenital limb deficiency can sometimes, although rarely, experience phantom pains. This suggests that there is a central representation of the limb responsible for painful sensations. Currently, theories are based on altered neurological pathways and cortical reorganization.
Phantom pain
1918041#2
Phantom limb sensation is any sensory phenomenon (except pain) which is felt at an absent limb or a portion of the limb. It has been known that at least 80% of amputees experience phantom sensations at some time of their lives. Some experience some level of this phantom pain and feeling in the missing limb for the rest of their lives.
Phantom pain
1918041#5
Symptoms include:
Onset within the first few days of amputation.
Comes and goes or is continuous.
Often affects the part of the limb farthest from the body, such as the foot of an amputated leg
May be described as shooting, stabbing, boring, squeezing, throbbing or burning
Sometimes feels as if the phantom part is forced into an uncomfortable position
May be triggered by pressure on the remaining part of the limb or emotional stress
Phantom limb pain and phantom limb sensations are linked, but must be differentiated from one another. While phantom limb sensations are experienced by those with congenital limb deficiency, spinal cord injury, and amputation, phantom limb pain occurs almost exclusively as a result of amputation. Almost immediately following the amputation of a limb, 90–98% of patients report experiencing a phantom sensation. Nearly 75% of individuals experience the phantom as soon as anesthesia wears off, and the remaining 25% of patients experience phantoms within a few days or weeks. Of those experiencing innocuous sensations, a majority of patients also report distinct painful sensations.
Phantom pain
1918041#1
Sensations are recorded most frequently following the amputation of an arm or a leg, but may also occur following the removal of a breast, teeth, or an internal organ. Phantom limb pain is the feeling of pain in an absent limb or a portion of a limb. The pain sensation varies from individual to individual.
Phantom pain
40629843#9
It has been suggested that symptoms of mirror-touch synesthesia can occur in amputees. 98% of amputees report phantom sensations in their amputated limb, and one of the studied treatments for phantom limb pain has involved a mirror box. In this treatment, the amputee places their good arm into a mirror box, allowing the image of the arm to reflect where the amputated arm normally would be. When touch is applied to the good arm, amputees have reported corresponding sensations in their phantom limb. These cases can be considered mirror-touch synesthesia because a visual stimulus was able to elicit a tactile sensation. Studies have looked further into determining whether amputees actually experience mirror touch synesthesia. Four amputees were recruited in a study and asked to observe an assistant's arm being touched at various angles. 61 out of the 64 trials experienced mirror-touch sensations, and when the arm was wiggled, the sensations were enhanced. Finally, one amputee experienced a cold sensation when observing ice cubes touching the assistant's arm. Although there is evidence that mirror-touch synesthesia occurs in amputees, recent data has been inconclusive.
Mirror-touch synesthesia
1918041#10
Under ordinary circumstances, the genetically determined circuitry in the brain remains largely stable throughout life. It was thought, until about 30 years ago, that no new neural circuits could be formed in the adult mammalian brain. Recently, functional MRI studies in amputees have shown that almost all patients have experienced motor cortical remapping. The majority of motor reorganization has occurred as a downward shift of the hand area of the cortex onto the area of face representation, especially the lips. Sometimes there is a side shift of the hand motor cortex to the ipsilateral cortex. In patients with phantom limb pain, the reorganization was great enough to cause a change in cortical lip representation into the hand areas only during lip movements. It has also been found that there is a high correlation between the magnitude of phantom limb pain and the extent to which the shift of the cortical representation of the mouth into the hand area in motor and somatosensory cortical reorganization has occurred. Additionally, as phantom pains in upper extremity amputees increased, there was a higher degree of medial shift of the facial motor representation. There are multiple theories that try to explain how cortical remapping occurs in amputees, but none have been supported to a great extent.
Phantom pain
24373#9
The prevalence of phantom pain in upper limb amputees is nearly 82%, and in lower limb amputees is 54%. One study found that eight days after amputation, 72% of patients had phantom limb pain, and six months later, 67% reported it. Some amputees experience continuous pain that varies in intensity or quality; others experience several bouts of pain per day, or it may reoccur less often. It is often described as shooting, crushing, burning or cramping. If the pain is continuous for a long period, parts of the intact body may become sensitized, so that touching them evokes pain in the phantom limb. Phantom limb pain may accompany urination or defecation.
Pain
41113755#10
Phantom limbs are sensations felt by amputees that make it feel like their amputated extremity is still there. Sometimes amputees can experience pain from their phantom limbs; this is called phantom limb pain (PLP).
Cortical remapping
53116300#25
Kean begins the chapter with the sad tale of George Dedlow. George Dedlow had fought in the Civil War and in turn had both his arms and both his legs amputated for various reasons. These amputations brought on another neurological phenomenon: phantom limbs. George Dedlow, amongst millions of other war amputees, felt pain in limbs that he did not have.
The Tale of the Dueling Neurosurgeons
4478702#4
In limb amputees, some, but not all, studies have found a correlation between preoperative pain in the affected limb and postoperative phantom pain. There is a significant association between painful and non-painful phantom experiences, preoperative pain in the symptomatic eye and headache. Based on the present data, it is difficult to determine if headaches or preoperative eye pain play a causal role in the development of phantom phenomena or if headache, preoperative eye pain, and postoperative phantom eye experiences are only epiphenomena of an underlying factor. However, a study in humans demonstrated that experimental pain leads to a rapid reorganization of the somatosensory cortex. This study suggests that preoperative and postoperative pain may be an important co-factor for somatosensory reorganization and the development of phantom experiences.
Phantom eye syndrome
14782003#19
Phantom limbs are a phenomenon which occurs following amputation of a limb from an individual. In 90–98% of cases, amputees report feeling all or part of the limb or body part still there, taking up space. The amputee may perceive a limb under full control, or paralyzed. A common side effect of phantom limbs is phantom limb pain. The neurophysiological mechanisms by which phantom limbs occur is still under debate. A common theory posits that the afferent neurons, since deafferented due to amputation, typically remap to adjacent cortical regions within the brain. This can cause amputees to report feeling their missing limb being touched when a seemingly unrelated part of the body is stimulated (such as if the face is touched, but the amputee also feels their missing arm being stroked in a specific location). Another facet of phantom limbs is that the efferent copy (motor feedback) responsible for reporting on position to the body schema does not attenuate quickly. Thus the missing body part may be attributed by the amputee to still be in a fixed or movable position.
Body schema
41119526#7
Phantom limb pain is a type of tactile hallucination because it creates a sensation of excruciating pain in a limb that has been amputated. In 1996, VS Ramachandran conducted a research on several amputees to pinpoint the neural reasons behind these illusionary pains. Most of these amputees that had an unbearable phantom limb pain are reported by patients whose limb was paralyzed before amputation. VS Ramachandran proposed the "learned paralysis" hypothesis. The hypothesis suggested that every time the patients tried to move their paralyzed limb, they received sensory feedback (through vision and proprioception) that the limb did not move. This feedback hardwired itself into the brain circuitry, so that, even when the limb was no longer present, the brain had learned that the phantom limb was paralyzed. As a treatment for phantom limb pains, VS Ramachandran devised a mirror box that would superimpose the mirror image of the normal arm in place of the missing arm and the patient would immediately be relieved of the pain. This suggested that the brain had a plastic nature in the somatosensory system and the brain had reorganized its somatosensory region to accommodate for this new change. Patients that experience this phantom limb pain are very important in research studies for their role in determining brain plasticity. The vivid tactile sensation of the arm that is no longer present suggest the highly complex nature of the brain to reorganize different functions which were once thought to be hardwired to specific regions (localization).
Tactile hallucination