Neuropathic pain

1
Neuropathic pain

• 1. Mechanism
• 2. Characteristic
• 3. Diagnosis
• 4. Treatment

2
Neuropathic pain

• Mechanism of pain caused by cancer
• nerve compression - nerve root compression caused
  by a collapsed vertebra
• total tumor mass neoplasm surrounding
  inflammation
• nerve infiltration by cancer
• nerve injury

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Neuropathic pain

• Mechanism of pain caused by treatment
• postoperative (neurotomy)
• phantom limb pain, post-mastectomy pain
• radiotherapy (fibrosis) e.g. Brachial plexopathy
• chemotherapy - peripheral neuropathy
  (wincristine, cisplatine, taxol)

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Neuropathic pain

• Mechanism of pain
• post-herpetic neuralgia
• diabetic neuropathy
• post-stroke pain
• uraemic neuropathy

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Neuropathic pain

• Pain characteristic
• superficial burning pain
• spontaneous stabbing/shooting pain
• boring and radiating pain
• allodynia - pain caused by a stimulus which does
  not normally provoke pain
• hyperalgesia - an increased response to a
  stimulus which is normally painful

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Neuropathic pain

• Diagnosis
• history
• clinical examination
• neurological examination
• MRI / CT

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Neuropathic pain

• Treatment
• I. Adiuvant analgesics
• II. Corticosteroids
• III. Analgesics (opioids)
• IV. Neurolysis, spinal analgesia

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Neuropathic pain

• Corticosteroids (reduces total tumor mass) e.g.
  Dexamethason 16-24mg at the begining and then
  reduse dose
• Antidepressants - tricyclic antidepressants
  (amitriptyline, desipramine, doxepin, imipramine,
  clomipramine)
• SSRI (paroxetine, citalopram, fluoxetine)

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Neuropathic pain

• Amitriptyline is effective in migraine and other
  types of headache, chronic low back pain,
  post-herpetic neuralgia, fibromialgia, painful
  diabetic polyneuropathy, central pain, cancer
  pain.
• Superficial burning pain, allodynia tricyclic
  antidepressants
• 10-25mg nocte at the begining max 75mg
• relief may not occur for 4-5 days, for effect
  you have to wait even 1-2 weeks

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Neuropathic pain

• Anticonvulsants - carbamazepine, gabapentin,
  valproate, oxcarbazepine, lamotrigine
• spontaneous stabbing/shooting pain
• carbamazepine 200-1600mg effect after 10-14 days
• adverse effects!
• gabapentin - 300-3600mg effect after one week

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Neuropathic pain

• Other drugs
• oral local anasthetics - mexiletine 450-600mg
  lignocaine infusions
• NMDA receptor antagonists - dextromethorphan,
  ketamine (in subanaesthetic doses), bupivacaine,
  methadon
• muscle relaxants - Baclofen 10-15mg gtgt75-100mg
• topical agents - capsaicin, lignocaine patch,
  EMLA
• benzodiazepines and neuroleptics
• spinal analgesia - epidural and intrathecal
  routes.

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A 4-step analgesic ladder used either alone or in
conjunction with the WHO 3-step ladder
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Bone pain

• 1. Mechanism
• 2. Pain characteristic
• 3. Diagnosis
• 4. Treatment

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Bone pain

• Mechanism
• metastases - breast, prostate, thyroid, kidney,
  lung, colon
• cancer infiltration of the bone
• pathologic fracture

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Bone pain

• Pain characteristic
• - continuous, aching and localized pain
• - is exacerbated by movements and sneezing
• - may be unifocal
• multifocal
• generalized

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Bone metastases

• Symptoms
• pain (75)
• neurological symptoms
• pathologic fracture
• hypercalcaemia
• bone marrow failure

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Bone pain

• Diagnosis
• history
• clinical examination
• rtg
• scintigram
• MRI / CT

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Bone pain

• Treatment
• surgery - bone stabilisation, tumor excision
• radiation therapy - is usually considered when
  bone pain is focal and poorly controlled with an
  opioid
• chemotherapy (chemosensitive tumors)
• hormonotherapy (hormonosensitive tumors - breast,
  prostate)

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Bone pain

• Radiopharmaceuticals that are absorbed at areas
  of high bone turnover - strontium-89,
  rhenium-186, samarium-153
• strontium is only potentially effective in
  treatment of pain due to osteoblastic bone
  lessions or lession with an osteoblastic
  component e.g. prostate cancer metastases
• strontium
• - initial clinical response occurs in 7-21 days
• - the usual duration of benefit is 3-6 months

20
Bone pain

• Non-steroidal anti-inflammatory drugs (NSAID)
• opioids
• corticosteroids
• bisphosphonates (clodronate, pamidronate)
• calcitonin
• neurolysis, spinal analgesia

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Bone pain

• Bisphosphonates
• - inhibit osteoclast activity and reduce bone
  resorption
• -provide analgesia and decrease the use of
  analgesics
• clodronate
• - intravenous dose 600mg weekly
• - oral dose - 1600mg daily
• pamidronate
• - intravenous dose 60-90mg every 3-4 weeks
• - is safe in patients with impaired renal
  function
• - adverse effect occasional hypocalcaemia,
  nausea

22
Bone pain

• Calcitonin mechanism of action is unclear
• - increase endorphin levels in the central
  nervous system
• - interact with the serotonergic system
• - anti-inflammatory action
• - direct effect on osteoclasts
• calcitonin
• - subcutaneous - relatively low dose at the
  begining, then gradually increased to 200 IU
• - intranasal- 200 IU in one nostril alternating
  nostril everyday

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Spinal cord compression

• Neurological emergency
• 3-5 of patients with advanced cancer
• 40 is associated with cancers of the breast,
  lung, prostate
• others are associated with renal cell cancer,
  lymphoma, myeloma, melanoma, sarcoma, colorectal
  cancer
• very rarely spinal cord syndromes are due to
  epidural or cord metastases

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Spinal cord compression

• Mechanism of compression
• - metastatic spread to vertebral body or pedicle
  - 85
• - tumor extension through intervertebral
  foramina - 10
• - intramedullary primary - 4
• - haematogenous dissemination - epidural space -
  1

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Spinal cord compression

• Clinical presentation pain (gt90)
• - pain of long duration which suddenly changes
• -pain is aggravated by lying down
• - pain may occur spontaneously
• - radicular pains are often exacerbated by neck
  flexion or straight leg raising, by coughing,
  sneezing or straining
• - funicular pain is less sharp, has a more
  diffuse distribution and is sometimes described
  as a cold unpleasant sensation

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Spinal cord compression

• Clinical presentation
• - weakness gt 75
• - paraesthesiae
• - sensory loss (gt50) starting in the feet and
  moving proximally
• (is helpful in defining the level of the
  compression)
• - sphincter dysfunction gt40
• loss of sphincter function is a bad prognostic
  sign

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Spinal cord compression

• Diagnosis
• - history
• - clinical examination
• - neurological examination
• - rtg - shows vertebral metastasis / collapse
• - MRI is the investigation of choice
• - CT with myelography may be helpful if MRI is
  not available

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Spinal cord compression

• Treatment
• - high-dose steroids and radiation should be
  offered to all patients.
• Steroids can reduce pain and preserve
  neurological function
• initial dosage - 100mg i.v.bolus (usually
  24-50mg) followed orally
• halving of the dose every third day until the end
  of radiation

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Spinal cord compression

• Treatment
• - surgery is only occasionally indicated
• - solitary vertebral metastasis
• - neurological symptoms and signs progress
  despite radiotherapy and high dose dexamethason
• - vertebral body resection with anterior spinal
  stabilization is generally the operation of choice

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Corticosteroids in palliative care

• Special indications (Dexamethason 2x8mg 10-14
  days)
• superior vena cava syndrome
• lymphadenopathy
• lymphangitis carcinomatosa
• obstruction of a hollow viscus (e.g. Bowel,
  ureter)
• postradiation inflamatory
• pericarditis exudative
• hypercalcaemia
• hormonal therapy

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Corticosteroids in palliative care

• Neuropathic pain
• bone pain
• neuropathic pain from infiltration or compression
  of neural structures
• increased intracranial pressure
• arthralgia
• neuromyopathy

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Corticosteroids in palliative care

• Other indications
• anorexia
• cachexia
• difficulty with breathing
• nausea, vomiting
• fever