What is Reflex Sympathetic Dystrophy (RSD), also known as Complex Regional Pain Syndrome (CRPS)?

What is RSD (Reflex Sympathetic Dystrophy)?

RSD, now called Complex Regional Pain Syndrome (CRPS), is a chronic neuropathic pain condition characterized by excruciating, disproportionate pain in a limb following trauma or injury, accompanied by sensory, motor, autonomic, and trophic changes. 1

Historical Context and Current Terminology

RSD is the outdated term for what is now classified as CRPS Type I, which occurs without identifiable nerve injury, while CRPS Type II occurs after confirmed nerve damage. 1, 2 The terminology changed to better reflect the complex, multifactorial nature of the condition involving somatic, psychological, and behavioral components. 3

Clinical Presentation

Pain Characteristics

• Excruciating, burning pain that is disproportionate to the initial injury and worsens with touch or stimulation (allodynia). 1, 4
• Pain gradually increases in intensity and spreads within the affected limb, sometimes extending to the contralateral limb. 1, 4
• The condition typically does not demonstrate placebo response except at very early time points (15-30 minutes), distinguishing it from other pain syndromes. 1, 4

Sensory Abnormalities

• Allodynia (pain from normally non-painful stimuli) and hyperalgesia (exaggerated pain response) are hallmark features. 1, 5

Autonomic Dysfunction

• Temperature dysregulation with affected limb feeling warmer or cooler than the contralateral side. 1, 5
• Skin color changes (mottled, red, or pale appearance). 1, 5
• Abnormal sweating patterns (hyperhidrosis or anhidrosis). 1, 5

Motor Impairment

• Functional limb weakness and decreased active range of motion. 1, 5
• Tremor or dystonia may develop in chronic cases. 2

Trophic Changes (in chronic cases)

• Hair loss, nail changes, and skin texture alterations. 1, 5
• Tissue changes and skin discoloration. 1, 4

Diagnostic Approach

Clinical Diagnosis

The diagnosis is primarily clinical, based on the Budapest Criteria, requiring symptoms present for at least 12 months to be considered chronic. 1, 2 The critical distinction between Type I and Type II is documentation of nerve injury—its presence defines Type II, while its absence defines Type I. 1

Imaging Studies

• Three-phase bone scintigraphy is the most useful imaging modality with pooled sensitivity of 78% and specificity of 88%, though it has high specificity for ruling out CRPS. 6, 1
• MRI has higher specificity (91%) but lower sensitivity (35%) for CRPS Type I, making it unsuitable as a screening test but useful for visualizing nerve lesions in Type II. 1

Treatment Algorithm

First-Line: Physical Therapy Foundation

Physical and occupational therapy are the cornerstone of CRPS treatment, with all other interventions serving to facilitate participation in rehabilitation. 1, 7 This includes:

• Gentle stretching and mobilization with focus on increasing range of motion. 4, 5
• Active range of motion exercises that gradually increase. 4, 5
• Sensorimotor integration training and graded motor imagery. 1, 2

Second-Line: Pharmacological Support

• Analgesics (NSAIDs, acetaminophen) to enable physical therapy participation, not as primary treatment. 1, 4, 5
• Oral corticosteroids (30-50 mg daily for 3-5 days, then taper over 1-2 weeks) to reduce inflammation and edema. 4
• Gabapentinoids for neuropathic pain component. 2

Third-Line: Interventional Procedures

• Sympathetic nerve blocks (stellate ganglion blocks for upper extremity, lumbar sympathetic blocks for lower extremity) for moderate to severe cases with sympathetic dysfunction, used only when demonstrating consistent improvement and increasing duration of relief with each successive block. 1, 4, 5
• Blocks should NOT be continued indefinitely without documented progressive improvement. 1, 4

Fourth-Line: Neuromodulation

• Spinal cord stimulation for refractory cases that have not responded to conservative management and sympathetic blocks, requiring a trial before permanent implantation. 1, 4, 5

Adjunctive Therapies

• Cognitive behavioral therapy and stepped psychological interventions to reduce anxiety and avoidance behavior that perpetuate disability. 1, 8
• Bisphosphonates show potential benefit in some studies. 8

Critical Pitfalls to Avoid

• Never delay physical therapy waiting for pain to resolve—this worsens outcomes through disuse and pain upregulation mechanisms. 1, 4
• Do not continue sympathetic blocks indefinitely without documented progressive improvement and increasing duration of relief. 1, 4
• Avoid using peripheral somatic nerve blocks for long-term treatment. 4
• Do not use sympathetic blocks for non-CRPS neuropathic pain—this contradicts evidence-based guidelines. 1, 4
• Always document objective functional outcomes beyond pain scores (ADL improvements, cognitive function, work capacity) to justify continued interventional treatment. 1, 4

Monitoring Requirements

Evaluate CRPS patients at least twice annually by a specialist due to high recurrence risk. 1