Neurosurgery notes/Functional/Pain/Complex regional pain syndrome (CRPS)

Complex regional pain syndrome (CRPS)

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Pain

Aka

  • Causalgia (greek: kausis – burning, algos – pain)
  • Reflex sympathetic dystrophy

Types

  • CRPS Type I
    • Due to indirectly damage to surrounding tissue
    • AKA
      • Reflex sympathetic dystrophy
      • Causalgia minor
      • Shoulder-hand syndrome
      • Sudeck’s atrophy
    • Denoted less severe forms, and has been described after non-penetrating trauma
  • CRPS Type II
    • Due to direct injury to a nerve
    • Major causalgia
    • Follows nerve injury (originally described after high velocity missile injuries).
  • Post-op CRPS
    • Has been described following carpal tunnel surgery as well as surgery on the lumbar and cervical spine

Defination

  • A disproportionate pain syndrome caused by nerve damage and resultant sympathetic dysfunction

Patients exhibiting CRPS phenomenology are not a homogeneous group, and include:

  • Actual CRPS (for these, Mailis proposes the term “physiogenic RSD”): a complex set of neuropathic phenomena that may occur with or without nerve injury
  • Medical conditions distinct from CRPS but with signs and symptoms that mimic CRPS: vascular, inflammatory, neurologic…
  • The product of immobilization: as in severe pain avoidance behaviour, or at times psychiatric disorders
  • A factitious disorder with either a psychological basis (e.g. Munchausen’s syndrome) or for secondary gain (financial, drug seeking…) i.e., malingering

Pathogenesis (unknown)

  • Norepinephrine released at sympathetic terminals
  • Hypersensitivity secondary to denervation or sprouting

Clinical

  • Variable complex of signs and symptoms due to multiple aetiologies
  • Has no clinical criteria
  • Pain
  • Vascular changes:
    • Vasodilator (warm and pink) or
    • Vasoconstrictor (cold, mottled blue).
  • Trophic changes (may be partly or wholly due to immobility):
    • Dry/scaly skin,
    • Stiff joints,
    • Tapering fingers,
    • Ridged uncut nails,
    • Either long/course hair or loss of hair,
    • Sweating alterations (varies from anhidrosis to hyperhidrosis)

Diagnostic test

  • None

Diagnostic criteria (Budapest clinical diagnostic criteria for CRPS)

  • Continuing pain, which is disproportionate to any inciting event
  • Must report at least one symptom in three of the four following categories:
    • Sensory: reports of hyperesthesia and/or allodynia
    • Vasomotor: reports of temperature asymmetry and/or skin color changes and/or skin color asymmetry
    • Sudomotor/edema: reports of edema and/or sweating changes and/or sweating asymmetry
    • Motor/trophic: reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)
  • Must display at least one sign at time of evaluation in two or more of the following categories:
    • Sensory: evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or deep somatic pressure and/or joint movement)
    • Vasomotor: evidence of temperature asymmetry and/or skin color changes and/or asymmetry
    • Sudomotor/edema: evidence of edema and/or sweating changes and/or sweating asymmetry
    • Motor/trophic: evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)
  • There is no other diagnosis that better explains the signs and symptoms

Treatment

  • Medical treatment ineffective
    • High placebo response rate
  • Conservative management,
  • Interventional pain procedures
    • Sympathetic
      • Options
        • Stellate ganglion blocks
          • Stellate ganglion blocks for upper extremities and lumbar sympathetic blocks for lower extremities have been shown in trials to provide symptomatic and functional benefits
        • Lumbar sympathetic blocks
        • Intravenous regional sympathetic block, particularly for UE CRPS:
          • Agents used include guanethedine 20mg, reserpine, bretylium…,
          • Injected IV with arterial tourniquet (sphygmomanometer cuff) inflated for 10 min.
            • If no relief, repeat in 3–4 wks.
          • No better than placebo in several trials
      • Outcome
        • 18–25% have satisfactory long-lasting relief
      • In patients responsive to sympathetic blocks, RFA or phenol neurolysis may provide longer-term symptom control
        • RFA may be preferred to phenol based on reports of neuropathic pain symptoms secondary to phenol neurolysis
    • Spinal cord stimulation
      • Indicated If patients fail to obtain adequate symptom control with the Sympathetic blocks
    • Peripheral nerve stimulation
      • Indicated If patients fail to obtain adequate symptom control with the Sympathetic blocks
    • Spinal cord pump