Phantom Limb Syndrome - Pain, Incidence, Causes, Treatment

There can also be dissociation between the actual position of the limb and its felt position. Phantom limb is thus a sensation from an amputated or missing limb (even an internal organ). It is an illusion rather a delusion. The concept of phantom limbs has been known since antiquity. Silas Weir Mitchell introduced the term ‘phantom limb’; he was also the first one to give a clinical description. The origin of phantom and phantom pains remain as mysteries.

Incidence

90 to 98% of all patients experience a phantom almost immediately after the loss of a limb. The incidence of phantom limb is higher following a traumatic loss, or if there has been a pre-existing painful condition in the limb. Planned surgical amputation of a non-painful limb may account for fewer cases in comparison. Phantoms are reported far less often in early childhood.


Onset

In 75% of cases phantoms appear as soon as the anaesthetic wears off and the patient is conscious after surgery. A delay of days or weeks is seen in the rest. The limb affected or the place where the amputation have nothing to do with the onset.

Duration

The phantom that is present initially for a few days or weeks may gradually fade from consciousness. Phantoms that persisted for 44 to 57 years have also been reported. A disappeared phantom can be recalled by some patients by intense concentration. Sometimes rubbing the stump does this trick.

Body part

Phantoms are most often reported after amputation of an arm or leg. Reports have also come following the amputation of the breast, parts of the face and internal organs. People can have sensation of bowel movement and flatus even after the removal of sigmoid colon and rectum. Phantom erections and ejaculations have been reported in patients after the removal of penis.

Posture of the phantom

A phantom often occupies a habitual posture, e.g. a partially flexed elbow. A painful permanently clenched phantom hand has also been reported. Spontaneous changes in posture can occur. A person may wake up and find an unusual phantom posture and later recover the habitual posture.

‘Telescoping’

A phenomenon called telescoping may occur in phantoms. This refers to cases where the patient senses progressive shortening of his upper limbs. He/she feels that, after a period of time he/she is left with the phantom hand alone hanging from the stump.

Congenital phantoms

Children with congenitally missing limbs also experience phantom limbs.

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The Cause

Phantom limbs and phantom pains are still puzzles yet to be solved. Irritation in the severed nerve endings (called "neuromas") used to be perceived as the cause until recently. It is now proposed that a reorganization or ‘cross-wiring’ in those parts of the brain that receive inputs from the limbs and the body (somatosensory cortex) is responsible for phantom limbs. Imaging techniques like magnetoencephalography (MEG) have been used to verify this. The concept of remapping is, however, not a final one. Since the exact cause is yet to be confirmed it would wiser to not go into the details.

Treatment

Mirror box is the novel treatment available for phantom limb pain. It was invented by Vilayanur S. Ramachandran, a renowned neurologist. It is a box with two mirrors in the centre. The principle of artificial visual feedback is used. The patient is able to “move” his phantom limb; he may unclench it from painful positions. Long term improvements are possible. A case were complete elimination was achieved using mirror box has been reported.

Based on the concept of mirror box, further experiments are being carried out. “Immersive virtual reality” is a technique in which computer-generated simulations trick the somato-sensory areas of the brain just like the mirror box.

Spinal cord stimulation aids some patients. Drugs like antidepressants may be tried. Vibration therapy, acupuncture, hypnosis, and biofeedback are seldom effective.

A rapid progress has occurred in the last 5 years. We now know more about phantom limbs and their neurological basis. But conclusive theories that would completely explain the cause of phantom limbs are yet to be out. The functional significance of remapping is being searched for. The dynamic status of neuronal connections in the brain is a promising field for research.