What is Complex Regional Pain Syndrome (CRPS)?

Complex Regional Pain Syndrome (CRPS)

Complex Regional Pain Syndrome (CRPS) is a chronic pain condition characterized by excruciating pain that is disproportionate to the inciting injury, typically affecting a limb and accompanied by autonomic dysfunction, sensory abnormalities, and motor impairments. 1

Clinical Presentation and Diagnostic Features

CRPS typically develops following trauma or injury, often minor in nature, and presents with several characteristic features:

Pain Characteristics

• Severe, excruciating pain that is disproportionate to the inciting event
• Pain worsens with touch or stimulation (allodynia)
• Gradually increases in intensity and may spread beyond the initial site, sometimes to the contralateral limb 1
• Described as a "cold burning pain" in many cases

Associated Signs and Symptoms

• Autonomic dysfunction:

  • Vasomotor changes: skin discoloration, temperature differences (>1°C between affected and unaffected limbs)
  • Sudomotor abnormalities: altered sweating patterns
  • Edema of the affected area 1, 2

• Trophic changes:

  • Hair loss
  • Skin texture changes
  • Nail abnormalities 1

• Motor impairments:

  • Weakness
  • Decreased range of motion
  • Tremor
  • Dystonia 1, 2

Classification

CRPS is classified into two types:

1. CRPS Type I (formerly reflex sympathetic dystrophy): Occurs without identifiable nerve damage
2. CRPS Type II (formerly causalgia): Associated with confirmed nerve injury 3, 4

Pathophysiology

The pathophysiology of CRPS is complex and multifactorial, involving:

• Sympathetic nervous system dysregulation 1, 3
• Peripheral and central sensitization
• Neurogenic inflammation
• Maladaptive brain plasticity
• Potential autoimmune mechanisms 3, 4
• Altered nociception (nociplastic pain) 1

Diagnosis

Diagnosis is primarily clinical, based on the Budapest Criteria, as no specific diagnostic test exists for CRPS 5, 2. Key diagnostic elements include:

• Continuing pain disproportionate to the inciting event
• At least one symptom in three of four categories:
  1. Sensory: hyperalgesia, allodynia
  2. Vasomotor: temperature asymmetry, skin color changes
  3. Sudomotor/edema: sweating changes, edema
  4. Motor/trophic: decreased range of motion, weakness, tremor, trophic changes 2, 6

Management Approach

Management requires a multidisciplinary approach focusing on pain reduction and functional restoration:

Physical and Occupational Therapy (First-line)

• Graded motor imagery
• Mirror therapy
• Functional rehabilitation focusing on:
  • Encouraging normal movement patterns
  • Promoting optimal postural alignment
  • Gradual increase in limb use during functional activities 1, 5, 4

Pharmacological Interventions

• Neuropathic pain medications (gabapentinoids)
• Anti-inflammatory agents
• Bisphosphonates (shown benefit in studies) 5
• Corticosteroids (potential benefit in early stages)

Interventional Procedures

• Spinal cord stimulation (for refractory cases)
• Sympathetic nerve blocks (although evidence is limited) 5

Psychological Support

• Cognitive behavioral therapy
• Pain management strategies 5

Important Clinical Considerations

1. Avoid harmful interventions:

   • Prolonged immobilization
   • Serial casting for fixed functional dystonia (associated with worsening symptoms)
   • Long-term splinting (may prevent normal movement restoration) 1

2. Early recognition and treatment are crucial for better outcomes 5, 6

3. Monitor for complications:

   • Muscle atrophy
   • Joint contractures
   • Osteoporosis 4

4. Prognosis: Most patients, particularly younger individuals, recover gradually, but treatment can accelerate healing 4

Emerging Treatments

• Ketamine infusions
• Immunomodulatory therapies
• Advanced neuromodulation techniques 3, 4

CRPS remains a challenging condition to diagnose and treat, requiring vigilance from clinicians to identify it early and implement appropriate multidisciplinary management to improve outcomes and quality of life for affected individuals.