Morning Report

1
Morning Report

• Steven Hart

2
HPI

• 45 year old female presents to clinic to
  establish new PMD
• CC left leg pain
• Recent medical history
• Pain in left LE for 1 mo with several visits to
  ER
• left femoral thrombus and emboli to left lower
  extremity eventually diagnosed
• Left AKA required
• Now (6 weeks later) c/o persistent pain where
  lower left leg was and sensations in left leg.
• Started on coumadin prior to discharge

3
Physical exam

• C/w left AKA
• Incisions clean and healing well
• Non-tender, no erythema, skin intact
• Exam otherwise unremarkable

4
Topics

• Phantom Limb Pain (PLP)
• Definitions
• Epidemiology
• Etiology / Pathophysiology
• Evaluation / Differential
• Treatment
• Prevention / Short term
• Long term

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Definitions

• Stump pain
• Pain in the residual portion of the limb
• Phantom Limb Pain (PLP)
• A painful sensation perceived in a missing limb
  after amputation
• Phantom Limb Sensation (PLS)
• Any sensation of the missing limb (paresthesia,
  dysesthesia, hyperpathia) except pain.

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Epidemiology

• Phantom Limb Sensation (PLS)
• Occurs in 85 - 98 of amputees within 3 weeks of
  amputation
• 8 may occur after 1-12 months
• Usually resolves after 2 3 years spontaneously
  if PLP does not develop
• Location affects intensity and likelihood of PLS
• Proximal ie. Above the knees or elbows
• Dominant extremity

7
Epidemiology

• Phantom Limb Pain (PLP)
• 60-70 of amputes experience PLP
• Location again an important factor
• Proximal
• 68-88 hemipelvectomy
• 40-88 hip disarticulation
• 51 upper limb
• 20 AKA
• 0-2 BKA

8
Epidemiology

• Phantom Limb Pain (PLP) continued
• Time
• Occurs 1 week to decades after amputation
• Pain onset after one year in
• May diminish and eventually resolve with time
• More likely, however, it will persist chronically
• Pain in limb prior to amputation increases risk
  for PLP
• Pains in other parts of the body
• Headache
• Joint pain
• Sore throat
• Abd pain
• Back pain

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Epidemiology

• Stump Pain
• Occurs in about 50 of amputees
• Frequently associated with phantom pain

10
Etiology

• Neuromas
• Dominate theory until last 10-15 years
• Irritation of the severed nerve endings
• Inflammation resulted in anomalous signals to the
  brain perceived as pain.
• Treatments included removal of nerve endings or
  further amputation.
• Only resulted in temporary improvement
• Eventually pain returned, frequently worse
• Modern thought - One of many factors causing PLP

11
Etiology

• Neuroma their role
• ? mechanical/neurostimulation ?
• spontaneous and abnormal evoked activity ?
• ? in sodium channel production ?
• ? in sensitivity of neuromas to norepinephrine
• Thus, pain with stress or other emotional states
• A similar phenomenon occurs in the cell body of
  the dorsal root ganglia just upstream

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Etiology -spinal cord level

• ? signal from neuromas and doral root ganglia
  cell bodies ?
• ? activity of neurons in dorsal horns ?
• ? upregulation of several genes
• - especially receptive genes
• - ? in N-methyl-D-aspartate (NDMA)

13
Etiology -spinal cord level

• Anatomical reorganization (rewiring)
• Perph nerve transection ? degeneration of
  afferent C-fiber terminals in Lamina II
• These may replaced by A? mechanoreceptive
  afferents
• Results in pain evoked by simple touch

14
Etiology - Central mechanism

• Somatosensory cortex remapping
• PLS/PLP evoked by touching face in a hand amputee
• Verified by multiple neuroimaging studies in
  humans

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Etiology - Central mechanism

• Plastic changes occur in the Thalamus
• Stimulation of thalamus in amputees causes PLP
  and PLS
• Similar stimulation does not cause any pain in
  non-amputees

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Differential Diagnosis of PLP

• Radicular pain
• Disk herniation
• Angina
• Post herpetic neuralgia
• Metastatic cancer
• Infection / poor wound healing

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Treatment of PLP -Overview

• Poorly studied field
• placebo effect common
• Spontaneous resolution does happen
• Fewer than 10 of PLP patients receive lasting
  relief
• Frequently, neuropathic treatment recommended,
  but few studies to support this
• Most neuropathic treatment trials do not include
  PLP
• Prevention of PLP is a new area of interest

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Treatment of PLP -Overview

• Multiple approaches
• Prevention
• Medical
• Physical Therapy
• Nerve Blocks
• Nerve stimulation
• Transcutaneous, spinal cord, deep brain, motor
• ECT
• Psychological Therapy

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Treatment of PLP -Prevention

• Goal avoid/control the changes that lead to
  chronic pain
• Prevent or control pre, peri and post-operative
  pain
• Use of pre, intra and post-op epidural blocks has
  been shown to reduce occurrence of PLP at 12 mo
  post-op
• Mixed results in follow up studies

20
Treatment of PLP -Prevention

• Calcitonin infusions
• Ketamine
• Transcutaneous electrical stimulation

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Treatment of PLP -Medical Management

• Anti-depressants
• Tricyclic anti-depressants
• Anti-convulsants
• NMDA receptor antagonists
• Opiates
• Beta Blockers
• Misc

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Treatment of PLP -Medical Management

• Tricyclic anti-depressants
• Frequently used
• Well studied in other neuropathic pain syndromes
• Diabetes, post herpetic neuralgia
• Poorly studied in PLP
• One randomized study showed no effect, other
  studies showed some benefit

23
Treatment of PLP -Medical Management

• Anti-convulsants
• Carbamazepine
• Effective for intense, brief, lancinating type of
  pain
• Gabapentin
• Effective in one small randomized trial
• Topiramate
• Small randomized study supported it effectiveness

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Treatment of PLP -Medical Management

• Opiates
• Effective for both stump pain and PLP
• May affect cortical reorganization
• Considered the mainstay of treatment
• Tolerance/Addiction
• Most amputees have a short life expectancy
  because of underlying disease.
• Balance quality of life vs risk of opiate
  addiction/dependence

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Treatment of PLP -Medical Management

• NMDA receptor antagonists
• Ketamine effective, must be IV
• Memantine oral, ineffective
• Dextromethorphan
• Small randomized studies have supported its use.
• Improved feeling
• No, small sedation
• No increased side effects from placebo

26
Treatment of PLP -Physical Therapy

• Sensory discrimination training
• Designed to alter the cortical map
• Shown to significantly reduce PLP and cortical
  reorganization

27
Treatment of PLP -Neurostimulation

• Transcutaneous electrical nerve stimulation
• Spinal Cord Stimulation
• Deep brain stimulation
• Motor cortex stimulation
• All very preliminary

28
Treatment of PLP

• Acupuncture
• May provide short term relief
• ECT
• Several case reports of pain resolution after
  treatment
• Psychological Therapy
• Relaxation training
• hypnosis

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Conclusion

• PLP is common in amputees
• The cause is complicated and involves virtually
  all levels of the nervous system
• Prevention of chronic pain may be possible but
  further investigation is needed
• Chronic pain management is difficult and should
  be multifaceted
• There is little evidence to guide therapy at this
  time.