Phantom Limbs

““I feel dead appendages”I feel dead appendages”

What the Research Shows…General Info:General Info:

Almost all amputees experience some from of phantom Almost all amputees experience some from of phantom limb phenomena (e.g., pain, sensation, etc.) limb phenomena (e.g., pain, sensation, etc.)

In one study, over 75% of participants experienced In one study, over 75% of participants experienced phantom limb painphantom limb pain

If phantom limb pain is not present immediately following If phantom limb pain is not present immediately following the amputation, usually does not occur the amputation, usually does not occur

Phantom limb pain seems to be more severe in more distal Phantom limb pain seems to be more severe in more distal parts of phantom limb; described as “stabbing, throbbing, parts of phantom limb; described as “stabbing, throbbing, burning, or cramping” burning, or cramping”

Phantom limb pain more common in adult amputees, less Phantom limb pain more common in adult amputees, less common in child amputees, almost never present in common in child amputees, almost never present in congenital amputees congenital amputees

Suspected Neurological Causes Pain-Memory Hypothesis:Pain-Memory Hypothesis:

Idea that chronic pain present in the limb prior to Idea that chronic pain present in the limb prior to amputation results in continued sensation of pain after amputation results in continued sensation of pain after removal of limb. Value of this hypothesis is empirically removal of limb. Value of this hypothesis is empirically uncertain uncertain

Peripheral Nervous System Changes:Peripheral Nervous System Changes: Neuromas: Neuromas: small bulbs that form on end of damaged small bulbs that form on end of damaged

neurons (e.g,. amputated limbs), created sporadic neuronal neurons (e.g,. amputated limbs), created sporadic neuronal activity activity

Reorganization: Reorganization: Neurons that once innvervated the Neurons that once innvervated the amputated limb may make new connections to muscles, amputated limb may make new connections to muscles, fibers in stump fibers in stump

Phantom limb pain and stump pain seem to be linked Phantom limb pain and stump pain seem to be linked

Suspected Neurological Causes Reorganization of the Cortex

Primary Somatosensory CortexPrimary Somatosensory CortexArea of cortex that was mapped to limb prior Area of cortex that was mapped to limb prior

to amputation is invaded by inputs from to amputation is invaded by inputs from adjacent areas of somatosensory cortex (e.g., adjacent areas of somatosensory cortex (e.g., face and rest of fingers)face and rest of fingers)

Intensity of PLP seems to be related to the Intensity of PLP seems to be related to the degree of cortical reorganization degree of cortical reorganization

PLP could be a result of the incongruence of PLP could be a result of the incongruence of somatosensory input and motor intentionsomatosensory input and motor intention

Suspected Neurological Causes Reorganization of the Cortex

Primary Motor CortexPrimary Motor Cortex Can create sensations of phantom movement by Can create sensations of phantom movement by

stimulating area of motor cortex mapped to stimulating area of motor cortex mapped to amputated limb amputated limb

Stimulation of motor cortex mapped to amputated Stimulation of motor cortex mapped to amputated limb frequently (86% of trials) results in limb frequently (86% of trials) results in corresponding muscle contractions in stump corresponding muscle contractions in stump

The activation of the hand area of the motor cortex The activation of the hand area of the motor cortex continues to be associated with a hand movement continues to be associated with a hand movement despite the fact that the descending motor commands despite the fact that the descending motor commands generated by this activation now result in stump generated by this activation now result in stump muscle contractions. muscle contractions.

Suspected Neurological Causes Spinal Cord

PLP could be related to disinhibition of PLP could be related to disinhibition of components of the spinal cord – including components of the spinal cord – including downregulation of opioid receptors, damage downregulation of opioid receptors, damage to inhibitory GABA interneurons, and to inhibitory GABA interneurons, and spinal remapping of the lost limb. spinal remapping of the lost limb.

Treatment Current treatments: analgesic, antidepressants, stimulation are Current treatments: analgesic, antidepressants, stimulation are

minimally effective minimally effective visual, sensory, and motor feedback to the cortex might be an visual, sensory, and motor feedback to the cortex might be an

important determinant of phantom limb phenomena and pain important determinant of phantom limb phenomena and pain ProsthesisProsthesis:: using a motor-driven prosthesis that reads using a motor-driven prosthesis that reads

electrical signals in stump muscles and effects movement of electrical signals in stump muscles and effects movement of prosthesis seems to decrease PLP possibly due to reversal of prosthesis seems to decrease PLP possibly due to reversal of cortical reorganization cortical reorganization

Discrimination trainingDiscrimination training of stimuli by regimen of stimulation of stimuli by regimen of stimulation of stump = less pain and reversal of cortical reorganization of stump = less pain and reversal of cortical reorganization

PharmacologicalPharmacological: NMDA receptor agonists, GABA agonists : NMDA receptor agonists, GABA agonists Stimulation of cortical areasStimulation of cortical areas by TMS or direct current may by TMS or direct current may

be viable options be viable options Imagined movements of phantomImagined movements of phantom also helped – including also helped – including

mirror treatment (no controlled studies as of yet on mirror mirror treatment (no controlled studies as of yet on mirror treatment) treatment) http://youtube.com/watch?v=kzLUQR_hMqYhttp://youtube.com/watch?v=kzLUQR_hMqY

Mirror Treatment

A visual trick, the arm is placed in a box to A visual trick, the arm is placed in a box to reverse the image and make it appear like reverse the image and make it appear like the amputated limbthe amputated limb

Shifts the emphasis from the site of the pain Shifts the emphasis from the site of the pain back to the brainback to the brain

Its thought that the pain comes from the Its thought that the pain comes from the brain’s map of the body and what is brain’s map of the body and what is actually perceived (or no longer perceived)actually perceived (or no longer perceived)