Phantom limb

The term phantom limb indicates the fact that a person amputated by one member still feels the presence of it, generally in a painful way.

History

For a few decades, the Neurologie has shown that the brain was divided into many cerebral surfaces, corresponding for some to the sensory methods (Hubel and Wiesel 1979). One of the contemporary major discoveries is the fact that this organization is strongly defined by the Génome and will remain overall constant during the life of an individual (Wiesel and Hubel, 1963). This discovery brings an additional justification to the idea that it was not created, in the adult, of new connection in the Cerveau; phenomenon also supported by weak recovery post traumatic of the cerebral functions.

However, in the two last decades several studies on the consequences of Amputation in the somato-sensory Carte of the adult suggest that this vision of the Nervous system must be corrected (Wall, 1977). The experimentation in the animal showed that this chart could largely change and is at the origin of a new passion for the study of the phantom limbs.

The study of the phantom limbs provides an opportunity of including/understanding how the brain builds an image of the body and how this image is continuously rehabilitated according to the sensory stimuli.

The term of “phantom limbs” was used for the first time by Silas Weir Mitchell (1871) which in provided the first clear clinical description. The patients suffering from this phenomenon still feel a member amputee, and in certain cases of the Douleur S. the term is sometimes used to indicate dissociation between the felt position and the real position of the member (proprioceptive anomaly ). In these various cases, the patient knows that the feeling is not real .

The phantom limbs are probably known since antiquity and it developed a whole folklore around. When Lord Nelson lost his right-hand man in the attack missed by Santa Cruz of Tenerife, it tested pains; he regarded this feeling as a “direct proof of the existence of the heart” (Riddoch, 1941). Since the first descriptions of Mitchell (1872), there were hundreds of case, despite everything the problem was always regarded as a curiosity and few experiments related to the subject. A contrario certain authors consider that it is an excellent means to include/understand the internal organization of the brain and the Plasticité in the adult.

The first part of the article mainly uses work of Melzack (1992) which stressed that the role of the Nerf S of the stub in the phantom feeling, although important, belonged to a more complex unit. In particular, phantoms felt by people Aplasique S, (the Cross, 1992; Ramachandran, 1993; Melzack, 1994) cannot be explained by this model. That suggests that a “mental” representation of the member persists after amputation. The nature and the origin of this representation as well as the capacity of modification by the sensory experiment will be treated in the second part (mainly thanks to work of V.S. Ramachandran).

In 70% of the cases, the feeling phantoms remains painful even 25 years after the loss of a member (Sherman, 1984). The origin of the phantom pain remains as mysterious about it as the origin of the phantom itself.

The phenomenology of the phantom limbs

What to answer a patient with a phantom limb? Answers based on clinical knowledge of the phenomenon.

Frequency of the phenomenon

Almost immediately after the loss of a member, 90 to 98% of the patients test a phantom. The frequency of occurrence all the more increases if the loss is due to a Traumatisme extremely or if there was a pre-amputatoire pain, that if it is about a surgical amputation of a nonpainful member.

The phantom limb can have a transitory existence at the time of reflex actions due to an environment which subject the body to a practice taken before amputation with a weakened conscience of the patient (by the sleep for example, to rise and pose a non-existent foot per ground), or a conscience of exceptional danger (to clutch itself at the time of imbalance to an existing support with a amputated hand).

The phantoms are much less current in the young children. The major explanation comes owing to the fact that the image of the body would not be yet rather strong. According to the studies of Simmel (1962), the phantoms appear at 20% of the children amputees 2 years old, 25% between 2 and 4 years, 61% between 4 and 6 years, 75% between 6 and 8 and in 100% of the 8 year old children amputees.

When the image of the body is final in the adult, the prosthesis substituent with the member must have exact dimensions of the lost member: even size of foot, even length of leg, even imbalance if unbalanced posture acquired the amputation before (swing of basin, position of column). The image of the body is then réacquise within new limits, as during ageing.

Beginning of the feelings

The phantoms immediately appear in 75% of the cases, as soon as the effects of the Anesthésie are dissipated and that the patient regains consciousness, but they are sometimes delayed of a few days or a few weeks in the 25% remainder (Moser, 1948). Carlen and its collaborators (1978) found among the Israeli soldiers who underwent an amputation during the Guerre of Kippour (1973), 33% feeling phantom limbs immediately, 32% in the 24:00 and 34% in the following weeks.

The moment of the beginning of the feelings is neither related to the kind of member amputee, nor related to the place where the amputation is made Sunderland, 1978).

Duration of the feeling

In the majority of the cases, the phantom is present during a few days even a few weeks and is dissipated with time. The time of the rebuilding of image of the body defining the limit of oneself physical in space, with the way in which a child has a vision of the prospects evolving/moving with his size, is primarily that obtained by the rehabilitation and the acquisition of compensatory movements mitigating the new disorders. The use of drugs speed reducers of nerve impulses, unquestionable anti-pains, anti-epilepsy slows down the taking into account by the body of the new body envelope. In other cases, one notes a persistence during years seeing decades (30% of the patients, according to Sunderland, 1978). There exist cases where the phantom persisted during 44 years Livingston, 1945) and 57 years (Abbatucci, 1894). Certain patients are able to awake their phantom thanks to a strong concentration or by stimulating to them Moignon. In other cases like made Mitchell (1872) one awoke the feeling by electric stimulation of the stubs amputees, it is probably one of the reasons for which it is largely widespread that the cut nerves are the cause of the phantom feelings.

Parts of the body

Although the phantoms are reported most of the time after amputation of the hand or the leg, it was already observed in cases of cutback of the center (Scholz, 1993), on parts of the face (Hoffman, 1955; Sacks, 1992) with a possibility that only the connections of the components of the nervous system were cut without other ablation (Fisher 2002) or even some times for the Viscère S or the genitals (Ovesen, 1991). It is as to note as phantom erections and ejaculations were reported by amputees of the penis or Paraplégique S (Sunderland, 1978), or of the pains of the appendix after its ablation. These results suggest that in spite of an ablation, or because, there can be reminiscence of a sensory memory.

The promptness of the phantom seems to rise from the overactivity of the Cortex (from where the sharp feeling of phantom in the hand), but also of a pain, subjective, lives pre-amputatoire (which would explain why the phantoms more often arrive after a traumatic loss rather than after a surgical amputation). That would imply that factors as the pre-amputatoire observation of the member could modulate the promptness of the pain, which would have important clinical implications.

Posture of the phantom

The patients often describe the phantom like having a position “normal”, e.g an arm partially bent on the level of the elbow. However, of the spontaneous changes in the posture are current. For example, when the patient awakes the morning his arm is in an unusual and sometimes uncomfortable position, but its posture will begin again after a few minutes. Some times, in a temporary or more durable way, the member take a posture awkward and painful, e.g the arm is twisted behind the head. Oddly, the posture of the member and his pre-amputatoire form persists in the phantom (Katz and Melzack, 1990). A patient had the arm before amputation on a spider monkey, bent with level of the elbow and the fingers were bent; after the amputation, according to its dires, its phantom had the same posture. Who more is, if a deformed member is amputee, the deformation is often present in the phantom (Sunderland, 1978).

What is it perception of the phantom when the position of the stub changes? It is Mitchell (1872) which posed and answered this question, its results showed that the phantom followed the voluntary or involuntary movements of the stub, but oddly, among certain patients the phantom remained static in spite of the movements of the stub.

“Telescoping”

When the phantom starts to disappear from the Conscience, generally it is in a total way, but in approximately 50% of the cases - particularly for the upper limbs - the member shortens himself, condenses until more not being but the end of the stub (Weiss and Fishman, 1963; Jensen and Al, 1983). The reason of this telescoping of different the nstituants disappeared condensed in an existing end is not clear, but seems to have a bond with “the cortical Expansion”: With the example owing to the fact that the hand on-is represented in the Cortex somatosensoriel. Rogers and Ramachandran (1996) suggested that during an amputation of the arm, the brain was confronted with a surge of contradictory signals , e.g the surface related to the driving system sends orders to the phantom which are simultaneously projected in the Cervelet and the parietal lobes (phenomenon of “Réafférence”). For a normal person, this kind of order is checked by the proprioception, and a “ visual Feedback ” (“reinforcement of feeling” by the visual one), but the amputee does not lay out any more this feedback, from where the conflict. To solve this conflict, the brain has two options: to accept all the signals or to refuse them. It is probably one of the reasons for which the phantom disappears, but when the hand on-is represented in the somato-sensory cortex, this feeling is not inevitably blocked everywhere, from where the phenomenon of telescoping.

It has some times suggested that the phenomenon of telescoping is due to a dynamics of the representation of the member in the surface somato-sensory primary elections. This is improbable, because that does not make it possible to explain the frequent cases of patients being able to have the telescoping or to voluntarily extend their phantom. For example, a patient amputee under the elbow and whose hand generally telescoped on the level of the stub, saw his phantom extending to his normal size when it was to tighten the hand of somebody or to catch an object. It is this same patient which one often quotes in anecdote that he complains with his doctor when the latter withdraws a cup of the fingers to him - phantoms - causing an unexpected telescoping.

The existence of the phantom is not affected by the vision, to open or close the eyes does not make it appear or disappear.

Congenital phantom

Simmel (1962) claimed that the children reached of congenital aplasias did not test phantom feelings, but it became obvious that it is not always true (Weinstein and coll, 1964; Poeck, 1969; the Cross and coll, 1992). Weinstein and Al (1964) studies 13 aplasic congenital with phantom limbs, among whom 7 are able to voluntarily move their members, 4 others feel the phenomenon of telescoping. It was also brought back the case of 20 years a aplasic young woman, having only stubs of Humérus, feeling sharp phantom feelings gesticulatoires at the time of conversations.

the absence of visual feedback and proprioceptive confirmations should in the long run involve the causing rejection of the signals of the involuntary movements. However there exist lasting cases of persistences of the years at subjects aplasic, but the latter never had feedback.

These conjectures can be for certain validated, or not, grace the noninvasive medical imagery such as the MEG and IRMf. These assumptions suggest that the phantom limbs originate in an interaction between the genetics and the epigenetic one.

Conclusion

Recent treating work of the phenomenon of phantom limb provides many information on the emergence of new connections in the brain, like on the way in which the various methods - to touch, proprioception and vision - interact enter they in order to maintain a perception correct of reality. Feelings referred as at patient D.S. of the existence of cortical reorganization, but a residual epiphenomene of childhood or has is a proof a role in the adult brain? Except this interest for cerebral plasticity, the study of the phantom limbs will make it possible to explore the relation between cerebral activity and conscious experiment. As one saw, it is possible simultaneously to follow the perceptive and cerebral changes of a patient.

See too

Nociception
Mirror box
Amputation
IRMf
Neuropathologie

References

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