• Phantom limb pain
    • 3 phenomena after amputation
      • Phantom sensation
        • Usually occur immediately after amputation but can occur days-weeks later
        • Rarely a clinical problem and explanation is all that is necessary
      • Stump pain
        • Acute nociceptive pain that usually resolves in a few weeks
        • Can last months or years
        • May be due to localised pathology or development of a neuropathic process
        • Can be due to peripheral neuropathy (eg diabetes)
        • Revision only indicated if local pathology present
      • Phantom pain
        • Incidence may be as high as 50-75%
        • Normally occurs in the 1st week
        • Can be exacerbated by central neuraxial blockade or even precipitated by spinal block
        • If improvement is not seen in 6/12 the prospect of spontaneous recovery is poor
        • Can get phantom breast pain but is less common (15% or so) - it often improves in 2 yrs
        • Risk factors
          • Pre-amputation pain
          • Persistent stump pain
          • Bilateral amputations
          • LL amputations
          • Less frequent in children
    • Treatments
      • Multidisciplinary approach
      • Paracetamol/NSAIDs/Opiates all useful for initial pain relief in the post-op period
      • TCA and anticonvulsants may help in neuropathic pain
      • Ketamine, calcitonin and β-blockers are used with some success
      • Pre-emptive analgesia
        • Evidence is poor for this practice
      • Physical treatments
        • Heat, US, TENS, accupuncture, massage, adjustment of prosthesis and stump manipulation have all been used with reported success
        • Mirror box for voluntary unclenching
      • Psychology
        • Explanation, reassurance, hypnosis, CBT have been successful
      • Surgery
        • Very poor results
        • Spinal cord stimulation has been tried with some success
    • Pathophysiology of phantom limb pain
      • Peripheral
        • Ectopic discharge from nerves at amputation site
        • Increased sensitivity of neurons to mechanical and chemical stimuli
        • Ectopic discharge from cells in the DRG
        • Sympathetically mediated afferent input
      • Spinal cord mechanisms
        • Anatomical reorganisation - Aβ fibres (normally involved in touch) sprout connections to lamina I/II
        • Central sensitisation of dorsal horn cells mediated by NMDA, Substance P and CTRP
      • Supraspinal mechanisms
        • Area of somatosensory cortex coresponding to the missing limb begins to recieve information from adjacent areas of the somatosensory cortex
    • CEACCP
      Link:ceaccp.oxfordjournals.org/content/4/1/20.full.pdf