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Complex Regional Pain Syndrome (CRPS)

Basics

  • Types:
  • Type I (Reflex Sympathetic Dystrophy): no nerve injury

  • Type II (Causalgia): nerve injury present

  • Epidemiology:

  • Peak incidence: 50-70 years
  • Female predominance (3:1)
  • Often postmenopausal women affected
  • Upper extremities more commonly involved

  • Incidence: 5.46–26.2 per 100,000 (Type I); 0.82 per 100,000 (Type II)

  • Etiology & Pathophysiology:

  • Multifactorial; abnormal sympathetic reflex lowering pain threshold
  • Central sensitization with increased nociceptive neuron excitability
  • Exaggerated inflammatory neuropeptide release

  • CNS changes and possible autoimmune involvement

  • Risk Factors:

  • Trauma (fractures, sprains), especially distal radius fractures
  • Surgery (carpal tunnel release)
  • Burns, frostbite, lacerations
  • Immobilization/casting
  • Minor injuries (IV catheter, injections)
  • Polymyalgia rheumatica, MI, CVA

Diagnosis

  • Clinical Features (Budapest Criteria):
  • Continuing pain disproportionate to inciting event
  • Symptoms in ≥3 of 4 categories:
    • Sensory: hyperalgesia/allodynia
    • Vasomotor: skin temperature/color asymmetry
    • Sudomotor/edema: swelling, sweating changes
    • Motor/trophic: decreased motion, motor dysfunction, hair/nail/skin changes
  • Signs in ≥2 categories on examination

  • No other diagnosis explaining symptoms

  • History:

  • Persistent burning pain, swelling, poor limb function

  • Severity of initial injury may vary

  • Physical Exam:

  • Swollen, erythematous, shiny skin
  • Brittle nails, reduced hair

  • Limited active and passive range of motion

  • Differential Diagnosis:

  • Infection, hypertrophic scar, neuroma, CNS tumors, DVT, thoracic outlet syndrome, connective tissue disorders, factitious disorder

  • Diagnostic Tests:

  • Clinical diagnosis of exclusion
  • Labs: CBC, ESR
  • Imaging: X-rays (patchy demineralization 3-6 weeks post onset)
  • Three-phase bone scan (diffuse increased activity supportive)
  • EMG for nerve injury in Type II
  • Sudomotor function tests for autonomic involvement

Treatment

  • General Measures:
  • Discourage maladaptive behaviors (opioid seeking)
  • Early, aggressive mobilization and functional restoration

  • Avoid opioids if possible

  • Medications:

  • NSAIDs (early course; mixed evidence)
  • Corticosteroids: prednisone 30 mg/day tapered over weeks (supported by trials)
  • Gabapentin (600–1800 mg/day for 8 weeks)
  • Topical DMSO 50% cream (up to 5 times daily)
  • N-Acetylcysteine 600 mg TID
  • Bisphosphonates (alendronate 40 mg/day)
  • Nifedipine 20 mg/day (early benefit)

  • Tricyclic antidepressants: no strong evidence for pain relief, may help depression

  • Referral & Additional Therapies:

  • Psychological evaluation after 2 months for comorbidities
  • Physical and occupational therapy, including mirror therapy
  • Passive ROM under sedation with follow-up PT
  • Transcutaneous nerve stimulation (controversial)
  • Psychotherapy

  • Subdissociative ketamine infusions (limited evidence)

  • Surgery/Procedures:

  • Type II may respond to nerve-directed treatment
  • Sympathetic blocks (chemical/surgical) with caution
  • Cervicothoracic/lumbar sympathectomy: limited data; last resort
  • Dorsal root ganglion stimulation preferred over spinal cord stimulation
  • Intrathecal analgesia
  • Amputation: last resort with reported improved quality of life

  • Osteopathic manipulation (case reports)

  • Complementary & Alternative Medicine:

  • Vitamin C 500 mg/day may prevent CRPS post wrist fracture
  • Cognitive behavioral therapy, acupuncture, hypnosis, guided imagery, relaxation training, biofeedback, whirlpool baths

Ongoing Care

  • Weekly follow-up to monitor progress and add therapies

Patient Education

  • Encourage physical activity
  • Support groups such as Reflex Sympathetic Dystrophy Syndrome Association (http://rsds.org/)

Prognosis

  • Early treatment improves outcomes
  • Symptoms may persist lifelong if poorly responsive

Complications

  • Depression
  • Disability
  • Opioid dependence

Clinical Pearls: - Pain disproportionate to injury is key diagnostic clue. - Early pain control and mobility critical for recovery. - Avoid opioids where possible. - Multidisciplinary approach yields best outcomes.