This document discusses phantom limbs from the past to the present and future. It begins by introducing the topic and defining phantom limbs. It then discusses various concepts related to phantom limbs including: 1. The gate control theory of pain which proposes a spinal gating mechanism that modulates pain transmission. 2. The neuromatrix theory which proposes that the brain can generate body experiences without sensory input through neural networks in the brain. 3. Neural plasticity and cortical reorganization which allows the brain to adapt and change representations after amputation. It concludes by discussing various phenomena related to phantom limbs like their incidence, sensations, referral of sensations between limbs, and potential mechanisms of intermanual referral.

1. PHANTOM LIMBS
PAST, PRESENT, FUTURE
Dr. A.V. SRINIVASAN
Former Prof. of Neurology
HEAD-Institute of Neurology
Madras Medical College & Research
Institute, CHENNAI.
1

2. BY THE DEFICITS WE MAY KNOW THE TALENTS
BY THE EXCEPTION WE MAY DISCERN THE RULES
BY STUDYING THE PATHOLOGY WE MAY CONSTRUCT A MODEL
OF HEALTH
AND MOST IMPORTANT.
FROM THIS MODEL MAY EVOLVE THE INSIGHTS
AND TOOLS WE NEED TO AFFECT OUR OWN LIVES
MOULD OUR DESTINY CHANGE OURSELVES
AND OUR SOCIETY IN WAYS THAT, AS YET
WE CAN ONLY IMAGINE.
– Laurence Miller
2

3. INTRODUCTION
• `PHANTOM LIMB’ - SILAS WEIR
MITCHELL (1871)
• THE CENTRAL
REPRESENTATION OF THE
LIMB SURVIVES AFTER
AMPUTATION AND IS LARGELY
RESPONSIBLE FOR THE
ILLUSION OF A PHANTOM
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4. PHENOMENOLOGY OF
PHANTOM LIMBS
• UNDERSTANDING THE PAIN
CONCEPTS
• CONCEPT OF NEUROMATRIX
• NEURAL PLASTICITY
• CORTICAL REORGANISATION
MECHANISMS
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5. PAIN CONCEPTS
GATE CONTROL THEORY
- MELZACK & WALL 1965
1. A SPINAL GATING MECHANISM IN THE DORSAL
HORN OF THE SPINAL CORD
2. ACTIVITY IN LARGE FIBRES TENDS TO INHIBIT
TRANSMISSION (CLOSE THE GATE) AND
ACTIVITY IN SMALL FIBRE TENDS TO
FACILITATE TRANSMISSION (OPEN THE GATE)
3. NERVE IMPULSES THAT DESCEND FROM THE
BRAIN INFLUENCE THE SPINAL GATING
MECHANISM.
4. CENTRAL CONTROL TRIGGER
5

6. JOHN LOESER & MELZACK
1978
“YOU DON’T NEED A BODY TO FEEL A BODY” OR
THAT “THE BRAIN ITSELF CAN GENERATE EVERY
QUALITY OF EXPERIENCE WHICH IS NORMALLY
TRIGGERED BY SENSORY INPUT”
• NEW CONCEPTUAL NERVOUS SYSTEM –
MELZACK 1989
– BODY WE NORMALLY FEEL IS SUBSERVED BY
THE SAME NEURALPROCESSES IN THE BRAIN.
– ORIGINS OF PATTERNS THAT UNERLIE THE
QUALITIES OF STIMULI MAY TRIGGER THE
PATTERNS BUT DO NOT PRODUCE THEM.
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7. FOUR COMPONENTS OF NEW
CONCEPTUAL NERVOUS
SYSTEM
1. THE BODY-SELF NEUROMATRIX
2. CYCLICAL PROCESSING AND SYNTHESIS
IN WHICH THE NEUROSIGNATURE IS
PRODUCED.
3. SENTIENT NEURAL HUB WHICH
CONVERTS THE FLOW OF
NEUROSIGNATURES INTO FLOW OF
AWARENESS.
4. ACTIVATION OF AN ACTION
NEUROMATRIX TO PROVIDE THE
“PATTERN” OF MOVEMENTS TO BRING
ABOUT THE DESIRED GOAL.
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8. NEUROMATRIX
ANATOMICAL SUBSTRATE FOR BODY-SELF.
CONSISTS OF LARGE LOOPS BETWEEN THALAMUS & CORTEX
AS WELL AS BETWEEN CORTEX AND LIMBIC SYSTEM.
DETERMINED GENETICALLY AND LATER MODIFIED BY
SENSORY INPUTS.
LOOPS DIVERGE TO PERMIT PARALLEL PROCESSING AND
CONVERGE REPEATEDLY TO PERMIT INTERACTIONS.
NEURO SIGNATURE
REPEATED “CYCLICAL PROCESSING AND SYNTHESIS” OF
NERVE IMPULSES THROUGH THE NEUROMATRIX IMPARTS A
CHARACTERISTIC PATTERN - THE NEURO SIGNATURE.
THIS IS PRODUCED BY THE PATTERNS OF SYNAPTIC
CONNECTIONS IN THE ENTIRE NEUROMATRIX.
NEUROSIGNATURE IS A CONTINUOUS OUT FLOW FROM THE
BODY SELF NEUROMATRIX.
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9. NEUROSIGNATURE PATTERN BIFURCATES
SO THAT A PATTERN PROCEEDS TO
SENTIENT NEURAL HUB – WHERE THE
PATTERN IS CONVERTED INTO THE
EXPERIENCE OF MOVEMENT.
ACTION NEUROMATRIX – WHICH
PROVIDE THE PATTERNS OF MOVEMENTS
TO BRING ABOUT THE DESIRED GOAL
Neuromodule Neuronal Pool (AHC) Muscle
Sentient Neural hub Experience
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10. PLASTICITY IN THE
SOMATOSENSORY SYSTEM
RECENT MEG STUDIES SHOW THAT THE PENFIELD MAP IN
S1, CAN BE REORGANISED OVER A DISTANCE OF AT
LEAST 2 OR 3CMS EVEN IN ADULT BRAIN
MECHANISM OF REORGANISATION:
THE EXTENT OF THALAMOCORTICAL AXON
ARBORIZATIONS CAN BE QUITE LARGE – UPTO 1CM OR
MORE.
THE DISTANCE BETWEEN THE CORTICAL MAPS FOR THE
HAND AND FACE (I.E., ADJOINING AREAS) IS 1-2 CMS IN
MONKEYS AND EVEN GREATER IN HUMANS.
REORGANISATION CHANGES OCCUR VERY RAPIDLY (IN
WEEKS TIME).
THE PROBABLE MECHANISM OF CORTICAL
REORGANISATION IS THROUGH UNMASKING OF OCCULT
SYNAPSES
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11. PHANTOM LIMBS
Incidence
 ALMOST IMMEDIATELY AFTER THE LOSS OF A LIMB, BETWEEN
90 AND 98% OF ALL PATIENTS EXPERIENCE A VIVID PHANTOM.
 INCIDENCE IS HIGHER FOLLOWING A TRAUMATIC LOSS THAN
AFTER A PLANNED SURGICAL AMPUTATION OF A NON
PAINFUL LIMB.
 PHANTOMS ARE SEEN FAR LESS OFTEN IN EARLY
CHILDHOOD.
Onset:
 PHANTOMS APPEAR IMMEDIATELY IN 75% OF CASES, AS SOON
AS ANAESTHETIC WEARS OFF AND PATIENT REGAINS
CONSCIOUSNESS.
 IN THE REMAINING 25% IT APPEARS AFTER A FEW DAYS TO
WEEKS.
Duration:
 IN MANY CASES THE PHANTOM IS PRESENT INITIALLY FOR A
FEW DAYS OR WEEKS THEN GRADUALLY FADES FROM
CONSCIOUSNESS. IN OTHERS IT MAY PERSIST FOR YEARS,
EVEN DECADES.
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12. BODY PARTS
 MOST PHANTOMS ARE REPORTED AFTER AMPUTATION OF ARM,
(OR) LEG, BUT THEY HAVE ALSO BEEN REPORTED FOLLOWING
AMPUTATION OF THE BREAST, PARTS OF FACE (OR) SOMETIMES
EVEN INTERNAL VISCERA (E.G) ONE CAN HAVE SENSATIONS OF
BOWEL MOVEMENT AND FLATUS AFTER A COMPLETE REMOVAL
OF SIGMOID COLON AND RECTUM
 PHANTOM ‘ULCER PAINS’ AFTER PARTIAL GASTRECTOMY.
 PHANTOM ERECTION AND EJACULATION IN PARAPLEGICS, PATIENTS
WITH AMPUTATION OF PENIS.
 PHANTOM MENSTRUAL CRAMPS AFTER HYSTERECTOMY
 PHANTOM PAIN OF ACUTE APPENDICITIS AFTER ITS REMOVAL.
POSTURE OF THE PHANTOM
 PATIENT USUALLY SAYS THAT THE PHANTOM OCCUPIES A
‘HABITUAL’ POSTURE (EG) PARTIALLY FLEXED AT THE ELBOW,
WITH THE FOREARM PRONATED.
 SPONTANEOUS CHANGES IN POSTURE ALSO ARE COMMON.
SOMETIMES UNCOMFORTABLE POSTURE FOR A TRANSIENT
PERIOD.
 RARELY PERMANENTLY FIXED IN AN AWKWARD AND PAINFUL
POSTURE
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13. Telescoping:
 WHEN PHANTOM FADES FROM CONSCIOUSNESS, IT USUALLY
DOES SO COMPLETELY, BUT IN ~50% OF CASES – ESP. IN THOSE
INVOLVING THE UPPER LIMBS – THE ARM BECOMES
PROGRESSIVELY SHORTER UNTIL THE PATIENT IS LEFT WITH
JUST THE PHANTOM HAND ALONE, DANGLING FROM THE STUMP.
TELESCOPING MAY HAVE SOMETHING TO DO WITH CORTICAL
MAGNIFICATION, THE FACT THAT THE HAND IS VERY MUCH OVER-
REPRESENTED IN SOMATOSENSORY CORTEX.
Congenital Phantoms:
 THOUGH ORIGINALLY THOUGHT UNLIKELY, WEINSTEIN ET AL.,
(1964) STUDIED 13 CONGENITAL APLASICS WITH PHANTOM LIMBS
OF WHOM 7 WERE ABLE TO MOVE THE PHANTOM VOLUNTARILY
AND 4 EXPERIENCED ‘TELESCOPED’ PHANTOMS.
 IT IS THOUGHT THAT THESE PHANTOMS ARISE FROM THE
MONITORING OF REAFFERENCE SIGNALS DERIVED FROM THE
MOTOR COMMANDS SENT TO THE PHANTOM DURING
GESTICULATION.
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14. FACTORS ENHANCING (OR) ATTENUATING
THE PHANTOM
 Preamputation history:
 TRAUMATIC LIMBLOSS, PRE EXISTING PAINFUL LIMB PATHOLOGY -
↑ THE DURATION OF PHANTOM.
 Condition of stump:
SCARRING, NEUROMAS - ↑ THE DURATION OF PANTOM
 LOCAL ANESTHESIA PRESSURE CUFF ISCHEMIA, – CAUSE
PHANTOM FADE TEMPORARILY.
 HITTING THE STUMP- ↑ (OR) RESURRECT AN OCCULT PHANTOM.
 Central effects:
 REST & DISTRACTION - REDUCE THE SEVERITY OF PHANTOM PAIN
 EMOTIONAL SHOCK – AGGRAVATE THE PHANTOM PAIN
 Movement of the phantom:
 MANY PATIENTS WITH PHANTOM LIMBS CLAIM THEY CAN
GENERATE VOLUNTARY MOVEMENTS IN THEIR PHANTOM.
 INVOLUNTARY (OR) QUASIPURPOSIVE MOVEMENTS ARE ALSO
COMMON (PHANTOM MAY WAVE GOOD-BYE, FEND-OFF A BLOW,
BREAK A FALL OR REACH FOR THE TELEPHONE).
 COMPLETELY INVOLUNTARY MOVEMENTS E.G., HAND SUDDENLY
MOVING TO OCCUPY A NEW POSITION ARE ALSO VERY COMMON
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15. EXTINCTION OF REFERRED
SENSATIONS
 A 16 YEARS OLD GIRL WHO HAD SUSTAINED A BRACHIAL PLEXUS
AVULSION (LT) AND EXPERIENCED A SUPERNUMERARY PHANTOM
BRANCHING OFF FROM HER PARALYSED ELBOW. SHE HAD A
DISTINCT MAP ON THE FACE. IF THE EXAMINER TOUCHED OR
STROKED HER FACE AND THE NORMAL HAND SIMULTANEOUSLY,
THERE WAS A COMPLETE EXTINCTION OF THE REFERRED
SENSATIONS. SUCH EXTINCTION DID NOT OCCUR IF OTHER BODY
PARTS (E.G) THE CONTRA LATERAL SHOULDER, CONTRA LATERAL
CHEST AND CONTRALATERAL THIGH WERE TOUCHED
SIMULTANEOUSLY WITH THE FACE.
EMERGENCE OF ‘REPRESSED MEMORIES’ IN PHANTOMS:
 THERE IS CONTINUED EXISTENCE OF NOT ONLY THE ‘MEMORIES’
IN THE PHANTOM – OF SENSATIONS THAT EXISTED IN THE ARM
JUST PRIOR TO AMPUTATION – BUT ALSO THE RE EMERGENCE OF
LONG LOST MEMORIES PERTAINING TO THAT ARM. (E.G.) PATIENT
SOMETIMES CONTINUE TO FEEL A WEDDING RING (OR) A WATCH
BAND ON THE PHANTOM.
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16. INTER-MANUAL REFERRAL OF
TACTILE SENSATIONS
 IN 30% OF PATIENTS THEY ARE TOPOGRAPHICALLY ORGANISED
(E.G) TOUCHING THE THUMB ELICITS REFERRAL TOUCH IN THE
CONTRALATERAL PHANTOM THUMB.
 THE EFFECTS SEEM TO OCCUR FOR TOUCH BUT NOT FOR
TEMPERATURE AND PAIN. BECAUSE THESE MODALITIES ARE
POORLY REPRESENTED IN CORTEX AND NO COMMISSURAL
PATHWAYS EXIST FOR THESE MODALITIES.
 THE EFFECT WAS ENHANCED IF AN OPTICAL TRICK WAS USED
TO CONVEY THE ILLUSION THAT THE PATIENT COULD ACTUALLY
SEE THE PHANTOM BEING TOUCHED.
 IN MANY PATIENTS, MOVEMENTS OF THE REAL HAND, BOTH
ACTIVE AND PASSIVE, WERE REFERRED TO THE PHANTOM.
 REFERRAL WAS SEEN FROM THE INTACT HAND AND FOREARM
UPTO A LEVEL CORRESPONDING TO THE AMPUTATION OF THE
OTHER ARM.
 THE FACT THAT THESE EFFECTS WERE TOPOGRAPHICALLY
PRECISE AND MODALITY – SPECIFIC, THIS RULES OUT ANY
POSSIBILITY THAT THEY ARE DUE TO NON-SPECIFIC, ‘AROUSAL’
RESPONSE.
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17. MECHANISM OF INTERMANUAL
REFERRAL
 THE POSSIBILITY OF NEW ANATOMICAL CONNECTIONS IS RULED
OUT BY THE RAPIDLY OF THE REFERRAL.
 THE POSSIBLE MECHANISM IS DUE TO REACTIVATION OF PRE-
EXISTING CONNECTIONS LINKING THE TWO HANDS.
 EVEN IN NORMAL INDIVIDUALS, SENSORY INPUT FROM SAY, THE
LEFT THUMB MIGHT PROJECT NOT ONLY TO THE RIGHT
HEMISPHERE BUT, VIA UNIDENTIFIED COMMISSURAL PATHWAYS,
TO MIRROR-SYMMETRIC POINTS IN THE OTHER HEMISPHERE.
THIS LATENT INPUT MAY ORDINARILY BE TOO WEAK, BUT WHEN
THE RIGHT HAND IS AMPUTATED THIS INPUT MAY BECOME
EITHER DISINHIBITED OR PROGRESSIVELY STRENGTHENED, SO
THAT TOUCHING THE LEFT HAND EVOKES SENSATIONS IN THE
RIGHT HAND AS WELL. PERHAPS THERE ARE NO COMMISSURAL
PATHWAYS CONCERNED WITH PAIN AND TEMPERATURE, SO
THESE SENSATIONS ARE NOT REFERRED.
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18. PHANTOM LIMB PAIN
 > 70% - CONTINUED TO EXPERIENCE PHANTOM LIMB PAIN
AS MUCH AS 25 YEARS AFTER THE AMPUTATION
 A SMALL PERCENTAGE OF PATIENTS (14%) EXPERIENCED
A REDUCTION IN INTENSITY OF PAIN OVERTIME
MECHANISM
 ACTIVE BODY NEUROMATRIX, IN THE ABSENCE OF
MODULATING INPUTS FROM THE LIMBS (OR) BODY,
PRODUCES A SIGNATURE PATTERN THAT IS TRANSDUCED
IN THE SENTIENT NEURAL HUB INTO A HOT (OR) BURNING
QUALITY. THE CRAMPING PAIN, HOWEVER, MAY BE DUE TO
MESSAGES FROM THE ACTION NEUROMODULES TO MOVE
MUSCLES IN ORDER TO PRODUCE MOVEMENT.
 POSSIBLE ROLE FOR SYMPATHETIC NERVOUS SYSTEM
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19. TREATMENT OF PHANTOM PAIN
 In the past, the success rate for treatment of phantom pain
has been dismal. (1%).
 At least 43 ineffective treatment are there for phantom limb
pain.
 Sympathetic blocks and sympathectomy are useful for
burning phantom for upto 1 year.
 Lobotomies, major spinal surgery, surgical revision of the
residual limb, psychotherapy, psychoactive drugs, TENS,
Biofeedback treatments.
 Cramping phantom pain responds well to treatments which
result in preventing the residual limb from tensing up
abnormally, while burning phantom pain responds well to
treatments which will increase blood flow both in and out
of the residual limb. No treatments have been identified as
being consistently effective for shocking/shooting
phantom pain
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20. THEORIES OF PHANTOM
LIMBS
 THE STANDARD THEORY – ROLE OF STUMP
NEUROMAS
 ANOTHER THEORY STATES THAT
PHANTOM LIMBS IS DUE TO FREUDIAN
‘DENIAL’ WITH THE PAIN BEING A PART OF
THE ‘MOURNING’ PROCESS
 MELZACK (1992) – DUE TO PERSISTENCE
OF ‘NEUROSIGNATURE’ IN A ‘DIFFUSE
NEURAL MATRIX’
 REMAPPING HYPOTHESIS
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21. THEORIES OF PHANTOM LIMBS
Contd..,
MULTIFACTORIAL MODEL BY
V.S. RAMACHANDRAN ET AL.,
 Phantom limb experience depends on integrating
experiences from at least five different sources.
 From the stump neuromas.
 From remapping.
 Monitoring of corollary discharge from motor commands
to the limb.
 Primordial, genetically determined, internal ‘image’ of
one’s body.
 Vivid somatic memories of painful sensations (or) postures
of the original limb.
 Usually these five factors act to reinforce each other but
rarely there may be discrepancies that modify the clinical
picture. A single discrepancy could simply be neglected.
But if there are two subsets of cues – the cues within each
subset being mutually consistent but inconsistent with the
other subset, the end result leads to odd phenomenon
‘split’ the image into two (i.e. supernumerary phantoms)
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22. LEARNED PARALYSIS &
POSSIBILITY OF UNLEARING
• IN PATIENTS WHOM LIMB WAS PARALYSED
BEFORE AMPUTATION, BRAIN HAD “LEARNED”
THAT THE LIMB WAS PARALYSED. SO EVERY
TIME THE MESSAGE WENT FROM THE MOTOR
CORTEX TO THE LIMB, THE BRAIN RECEIVED
VISUAL FEEDBACK THAT THE LIMB WAS NOT
MOVING. THIS INFORMATION IS SOMEHOW
STAMPED INTO THE NEURAL CIRCUITRY OF
THE PARIETAL LOBES SO THAT THE BRAIN
‘LEARNS’ THAT THE LIMB IS FIXED IN THAT
POSITION. SO WHEN THE LIMB IS AMPUTATED,
THE BRAIN STILL ‘THINKS’ THE LIMB IS FIXED
AND THE NET RESULT IS A PARALYSED
PHANTOM LIMB
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23. VIRTUAL REALITY BOX
 This is made by placing a vertical 23mirror inside a
cardboard box with the roof of the box removed. The front
of the box has two holes in it, through which the patient
inserts his good arm and his phantom arm. The patient is
then asked to view the reflection of his normal hand in the
mirror, thus creating the illusion of two hands, when infact
the patient is only seeing the mirror reflection of the intact
hand.
 If he now sends motor commands to both arms to make
mirror-symmetric movements, he will have the illusion of
seeing his phantom hand resurrected and obeys to his
commands. i.e., he receives positive visual feedback
informing his brain that his phantom arm is moving
correctly. By using this researchers made the patients
unlearn the phantom paralysis, unclench the phantoms
during the spasms.
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24. FUTURE PROSPECTS
• WITH THE ADVENT OF MEG, fMRI, PET, MOST OF
THE SPECULATIVE CONJECTURES IN PHANTOM
LIMB PHENOMENON WILL BE VERIFIED TO GIVE
MORE INSIGHT INTO THE BRAIN FUNCTION.
• CONCEPTS OF LEARNED PARALYSIS AND
METHODS OF UNLEARNING IT MAY BE
EXTENDED TO THE AREAS OF STROKE,
APRAXIA AND DYSTONIA PATIENTS AND THEY
MAY BE BENEFITED BY THE VISUAL FEEDBACK
METHODS.
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25. CONCLUSION
• THE BRAIN DOES MORE THAN DETECT AND
ANALYSE INPUTS; IT GENERATES PERCEPTUAL
EXPERIENCE EVEN WHEN NO EXTERNAL
INPUTS OCCUR.
• IN SHORT, PHANTOM LIMBS ARE A MYSTERY
ONLY IF WE ASSUME THE BODY SENDS
SENSORY MESSAGES TO A PASSIVELY
RECEIVING BRAIN. PHANTOMS BECOME
COMPREHENSIBLE ONCE WE RECOGNIZE THAT
THE BRAIN GENERATES THE EXPERIENCE OF
THE BODY. SENSORY INPUTS MERELY
MODULATE THAT EXPERIENCE; THEY DO NOT
DIRECTLY CAUSE IT.
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26. Our path is cumbered with
guesses, presumptions and
conjunctures, untimely and sterile
fruitage of minds which cannot
bear to wait for the facts and are
ready to forget that the use of
hypothesises lies not in the
display of ingenuity but in the
labour of verification.
– CLIFFORD ALBUTT
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