see also:

• neurology
• erythromelalgia - episodic, chronic burning skin pain mainly feet but can affect hands, legs, arms, face
• Vic. Better Health Channel - pt. info sheet - RSD

• types of complex regional pain syndrome (CRPS):
  • type I: no evidence of nerve injury, formerly known as reflex sympathetic dystrophy (RSD) or Sudeck's atrophy
  • type II: associated with nerve injury, formerly known as causalgia
• it is a painful disorder of a limb presumably mediated via sympathetic nervous system injury or irritation.
• it is often precipitated by injury to a sympathetic nerve (which usually are located along peripheral arteries in limbs) &/or prolonged immobilisation and events which may initiate it include soft tissue injury (in 40%), fracture (in 25%), acute myocardial infarction (AMI/STEMI/NSTEMI) (in 12%), stroke (CVA) (in 3%), although no precipitating event was found in up to 35% of cases.
• before early ambulation was advocated, RSD occurred in 5-20% of patients with acute myocardial infarction (AMI/STEMI/NSTEMI) and 12-20% of patients with hemiplegia.
• accounts for 2-5% of adults, and up to 20% of paediatric patients at pain clinics
• adults: females 3.5 x males, and mainly upper limb
• paediatric: females 9.1 x males, and mainly lower limb
• highest prevalence in Caucasians
• emotional stress at the time may be an important factor.
• in all phases, there is decreased sympathetic outflow to the limb.

• severe burning and sometimes throbbing limb pain, with diffuse uncomfortable aching, sensitivity to light touch or cold causing pain sensation (allodynia), increased sensitivity to pain (hyperalgesia), and localised oedema.
• pain distribution does not relate to a nerve, nerve root or dermatome.
• variable vasomotor disturbances including altered color, temperature, sweating.
• most have a “hot, florid” initial phase although some start with the usual later “blue cold” phase - both of these phases are associated with swelling

• progression of soft tissue oedema, thickening of skin and articular tissues, muscle wasting, osteoporosis and development of brawny skin.
• may last 3-6 months

• most severe stage
• limitation of movement, shoulder-hand syndrome (capsular contraction of joints causing a frozen shoulder), contractures of fingers, waxy, trophic changes, brittle, ridged nails
• severe osteoporosis

• cervical nerve root impingement
• Pancoast's syndrome
• vasculitis
• rheumatoid arthritis
• peripheral neuropathy
• migratory osteolysis
• venous thrombosis
• arteriovenous fistulae
• progressive systemic sclerosis
• disuse atrophy
• angioedema

• essentially clinical
• CT not recommended at any stage
• bone scan findings are supportive and are useful in stage 1 and 2 - early scan (but AFTER 6 weeks from onset) is more sensitive (~97%) than late scans, and scanning after 6 months is generally not helpful.
• plain Xrays may be useful in stage 3 when osteoporotic findings are more pronounced
• MRI may be useful in stages 1 and 3

• early mobilisation
• prophylactic o vitamin C 500mg/d after distal radius fracture in adults seems to help, reducing incidence from 22% to 7% (UpToDate recommend use of vitamin C)
• non-steroidal anti-inflammatory drugs (NSAIDs)

• Rx is more effective if commenced in stage 1, BEFORE radiographic changes occur
• early referral to a pain Mx specialist
• early referral to physiotherapy for mobilisation rather than prolonged splinting, although little evidence that physio or OT improve outcomes in this condition.
• stress the importance of working to regain use of the affected limb while recognizing the difficulty of doing so in the face of ongoing pain.
• stress-management techniques
• cease smoking as smoking appears to double the risk of CRPS.
• pharmacologic Rx that appears to be better than placebo:
  • anticonvulsants such as gabapentin for neuropathic pain relief
  • bisphosphonates and/or nasal calcitonin to prevent osteoporosis and may have some benefit in pain reduction
  • corticosteroids such as prednisolone 30-80mg/d seems to help resolution, and appear to be more effective than non-steroidal anti-inflammatory drugs (NSAIDs)
  • tricyclic antidepressants such as amitryptyline for neuropathic pain relief
  • topical capsaicin 0.075% qid is useful in stage 1
  • regional sympathetic blocks
• stage 1 Rx:
  • topical capsaicin 0.075% qid - cease if too painful or no relief after 3-5 days
  • amitryptiline 25 mg at bedtime and increase the dose, as tolerated, to 150 mg
  • non-steroidal anti-inflammatory drugs (NSAIDs)
• refractory to stage 1 Rx after 1-2 weeks Rx:
  • steroid injections if local tender muscle points
  • add an anticonvulsant such as gabapentin
  • if pain persists, add calcitonin or bisphosphonates and prednisolone 1mg/kg daily for 3 days and if effective, continue and taper over 3 weeks
• stage 2 Rx:
  • as for stage 1
• stage 3 Rx:
  • pain Mx specialist referral