neuropathic pain

• neuropathic (nerve involvement) pain:

  • nerves have connective tissue that is innervated by nociceptors
  • so like muscles, nerves can produce nociceptive information to the CNS that might be interpreted as pain
  • Nerves also have surrounding structures like discs and ligaments that also have innervation
  • so if a nerve is mechanically stressed or compromised (e.g. compressed in the intervertebral foramen) then the nerve itself can be a source of nociceptive information, because its connective tissue is innervated - neural provocation tests where we stress the nerve will probably be positive
• neuropathic (nerve involvement) pain pt2:

  • some pts go onto developing neuropathic pain
  • arises through abnormal behaviour behaviour of the nerve itself, the abnormal neural firing
  • will often refer in a dermatomal or cutaneous distribution, depending on whether its a nerve route or nerve trunk thats being compromised
  • has certain qualities or is associated with sensations such as:
  • burning pain
  • paraesthesia
  • anaesthesia
  • dysesthesia (crawling)
  • allodynia - pain from something we dont normal find painful
  • often affected by stress/emotional factors
• neuropathic (nerve involvement) pain pt3:

  • neural integrity tests: altered reflexes, motor/sensory loss in a dermatomal/myotomal/cutaneous distribution
  • compared to nociceptive pain, neuropathic pain has a tendency for poorer stimulus-response relationship - amount of stress on the structure of pain may have disproportionate amounts of pain
• Common root neuropathic pain problems - Lumbar:

  • L3 - more commonly see pain pain coming from the back around to the anterior thigh
  • L4 - pain normally extending down the leg below the knee
  • L5 - pain the lateral aspects of the leg, then crosses down below the knee into the big toe
  • S1 - pain down the back of the posterolateral leg into the lateral border of the foot