What are the types of Complex Regional Pain Syndrome (CRPS)?

Types of Complex Regional Pain Syndrome (CRPS)

Complex Regional Pain Syndrome (CRPS) is classified into two main types: CRPS type I, which occurs without identifiable nerve injury, and CRPS type II, which develops following a specific nerve injury. 1

CRPS Type I

CRPS type I, formerly known as reflex sympathetic dystrophy (RSD), encompasses conditions where no specific nerve injury is present. Key characteristics include:

• Develops after trauma or injury that is often minor (e.g., ankle sprain, Colles' fracture)
• Pain disproportionate to the inciting event
• No identifiable nerve damage on examination or testing
• Accounts for the majority of CRPS cases
• May follow immobilization of an extremity 1, 2

CRPS Type II

CRPS type II, previously called causalgia, occurs after a confirmed peripheral nerve injury. Notable features include:

• Pain may extend beyond the distribution of the injured nerve
• Demonstrable nerve damage on clinical examination or diagnostic testing
• Less common than CRPS type I
• MRI may be useful in diagnosis due to its ability to directly visualize nerves and detect signs of muscle denervation 1

Clinical Presentation and Phases

Both types typically present with:

1. Early/Warm Phase (Inflammatory):

   • Local swelling and edema
   • Erythema and warmth
   • Increased sensitivity to touch (allodynia)
   • Hyperalgesia (exaggerated pain response)

2. Late/Cold Phase:

   • Persistent pain
   • Skin discoloration (often bluish)
   • Decreased temperature in affected area
   • Trophic changes (hair loss, skin changes, altered nail growth)
   • Motor impairment and reduced range of motion 2

Diagnostic Considerations

Diagnosis is primarily clinical, as there is no specific diagnostic test for CRPS. Imaging studies may help support the diagnosis:

• Three-phase bone scan: Has relatively high sensitivity (78%) and specificity (88%) for CRPS type I 1
• MRI: High specificity (91%) but lower sensitivity (35%) for CRPS type I 1
• Ultrasound: May show increased power Doppler flow in affected limbs with sensitivity of 73% and specificity of 92% 1

Treatment Approach

Early aggressive treatment improves prognosis. Management typically includes:

• Physical and occupational therapy to maintain function
• Pharmacological treatments (gabapentinoids, corticosteroids for acute CRPS)
• Interventional procedures (sympathetic blocks, neuromodulation)
• Psychological support to address comorbid anxiety and depression 3, 4, 2

Important Clinical Considerations

• CRPS can spread from the initially affected limb to the contralateral limb in some cases 1
• Unlike many pain syndromes, CRPS shows minimal placebo response except at very early time points 1
• Children with CRPS tend to respond better to multifaceted physical therapy than adults 4
• Vitamin C may have a preventive role in high-risk patients 4
• The condition can cause substantial physical, emotional, and financial burden 4

Early recognition and prompt initiation of treatment are crucial for improving outcomes in both types of CRPS, with emphasis on maintaining movement of the affected part, especially in early stages.