Phantom limbs past present-future

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Phantom limbs past present-future

  1. 1. PHANTOM LIMBSPAST, PRESENT, FUTURE Dr. A.V. SRINIVASAN Former Prof. of Neurology HEAD-Institute of NeurologyMadras Medical College & Research Institute, CHENNAI. 1
  2. 2. BY THE DEFICITS WE MAY KNOW THE TALENTSBY THE EXCEPTION WE MAY DISCERN THE RULESBY STUDYING THE PATHOLOGY WE MAY CONSTRUCT A MODELOF HEALTHAND MOST IMPORTANT.FROM THIS MODEL MAY EVOLVE THE INSIGHTSAND TOOLS WE NEED TO AFFECT OUR OWN LIVESMOULD OUR DESTINY CHANGE OURSELVESAND OUR SOCIETY IN WAYS THAT, AS YETWE CAN ONLY IMAGINE. – Laurence Miller 2
  3. 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 3
  4. 4. PHENOMENOLOGY OF PHANTOM LIMBS• UNDERSTANDING THE PAIN CONCEPTS• CONCEPT OF NEUROMATRIX• NEURAL PLASTICITY• CORTICAL REORGANISATION MECHANISMS 4
  5. 5. PAIN CONCEPTS GATE CONTROL THEORY - MELZACK & WALL 19651. A SPINAL GATING MECHANISM IN THE DORSAL HORN OF THE SPINAL CORD2. 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. 6. JOHN LOESER & MELZACK 1978“YOU DON’T NEED A BODY TO FEEL A BODY” ORTHAT “THE BRAIN ITSELF CAN GENERATE EVERYQUALITY OF EXPERIENCE WHICH IS NORMALLYTRIGGERED 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. 6
  7. 7. FOUR COMPONENTS OF NEW CONCEPTUAL NERVOUS SYSTEM1. THE BODY-SELF NEUROMATRIX2. 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. 7
  8. 8. NEUROMATRIXANATOMICAL SUBSTRATE FOR BODY-SELF.CONSISTS OF LARGE LOOPS BETWEEN THALAMUS & CORTEXAS WELL AS BETWEEN CORTEX AND LIMBIC SYSTEM.DETERMINED GENETICALLY AND LATER MODIFIED BYSENSORY INPUTS.LOOPS DIVERGE TO PERMIT PARALLEL PROCESSING ANDCONVERGE REPEATEDLY TO PERMIT INTERACTIONS. NEURO SIGNATUREREPEATED “CYCLICAL PROCESSING AND SYNTHESIS” OFNERVE IMPULSES THROUGH THE NEUROMATRIX IMPARTS ACHARACTERISTIC PATTERN - THE NEURO SIGNATURE.THIS IS PRODUCED BY THE PATTERNS OF SYNAPTICCONNECTIONS IN THE ENTIRE NEUROMATRIX.NEUROSIGNATURE IS A CONTINUOUS OUT FLOW FROM THEBODY SELF NEUROMATRIX. 8
  9. 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 GOALNeuromodule Neuronal Pool (AHC) Muscle Sentient Neural hub Experience 9
  10. 10. PLASTICITY IN THESOMATOSENSORY SYSTEMRECENT MEG STUDIES SHOW THAT THE PENFIELD MAP INS1, CAN BE REORGANISED OVER A DISTANCE OF ATLEAST 2 OR 3CMS EVEN IN ADULT BRAINMECHANISM OF REORGANISATION:THE EXTENT OF THALAMOCORTICAL AXONARBORIZATIONS CAN BE QUITE LARGE – UPTO 1CM ORMORE.THE DISTANCE BETWEEN THE CORTICAL MAPS FOR THEHAND AND FACE (I.E., ADJOINING AREAS) IS 1-2 CMS INMONKEYS AND EVEN GREATER IN HUMANS.REORGANISATION CHANGES OCCUR VERY RAPIDLY (INWEEKS TIME).THE PROBABLE MECHANISM OF CORTICALREORGANISATION IS THROUGH UNMASKING OF OCCULTSYNAPSES 10
  11. 11. PHANTOM LIMBSIncidence  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. 11
  12. 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 12
  13. 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. 13
  14. 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 14
  15. 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. 15
  16. 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. 16
  17. 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. 17
  18. 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 OVERTIMEMECHANISM 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 18
  19. 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 19
  20. 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 20
  21. 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) 21
  22. 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 22
  23. 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. 23
  24. 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. 24
  25. 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. 25
  26. 26. Our path is cumbered with guesses, presumptions andconjunctures, untimely and sterile fruitage of minds which cannotbear 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 26

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