What is Complex Regional Pain Syndrome (CRPS) in a patient with a history of Spinal Cord Injury (SCI)?

What is Complex Regional Pain Syndrome (CRPS)?

Complex Regional Pain Syndrome is a chronic neuropathic pain condition characterized by excruciating, disproportionate pain following trauma or surgery, accompanied by sensory, autonomic, motor, and trophic abnormalities that typically affect one or more limbs. 1

Definition and Classification

CRPS is subdivided into two distinct types based on the presence or absence of documented nerve injury 2, 1:

• Type I (formerly reflex sympathetic dystrophy): Occurs without an identifiable nerve injury despite thorough clinical evaluation 2, 1
• Type II (formerly causalgia): Develops after a confirmed nerve injury or lesion documented through clinical examination or diagnostic testing 2, 1

The critical diagnostic distinction is documentation of nerve injury—its presence defines Type II, while its absence defines Type I 1.

Clinical Presentation

Pain Characteristics

• Excruciating, burning pain that is disproportionate in magnitude or duration to the initial injury 1, 3
• Pain gradually increases in intensity and spreads within the affected limb, sometimes extending to the contralateral limb 1
• Worsens with touch or stimulation 1

Sensory Abnormalities

• Allodynia: Pain from normally non-painful stimuli 1, 4
• Hyperalgesia: Exaggerated pain response to painful stimuli 1, 4

Autonomic Dysfunction

• Temperature dysregulation in the affected limb 1
• Skin color changes (mottling, pallor, or erythema) 1
• Abnormal sweating patterns (hyperhidrosis or hypohidrosis) 1

Motor Impairment

• Functional limb weakness 1
• Decreased active range of motion 1
• Movement disorders in some cases 4

Trophic Changes (in chronic cases)

• Hair loss or abnormal hair growth 1
• Skin texture changes 1
• Nail changes 1
• Tissue atrophy 4

Diagnosis

The diagnosis of CRPS is primarily clinical, based on the Budapest Criteria, requiring symptoms present for at least 12 months to be considered chronic. 1

Imaging Studies

Three-phase bone scintigraphy is the most useful imaging modality for CRPS, with a pooled sensitivity of 78% and specificity of 88%. 2, 1 Bone scintigraphy has high specificity and can be used to rule out CRPS 2.

For Type I CRPS 2, 1:

• MRI: Higher specificity (91%) but lower sensitivity (35%), making it unsuitable as a screening test 2, 1
• Contrast-enhanced MRI may show soft tissue edema and bone marrow changes 2

For Type II CRPS 2, 1:

• MRI may provide additional diagnostic value by directly visualizing nerve lesions and detecting denervation changes 2, 1
• High-resolution ultrasound can visualize nerve pathology 2, 1

CRPS in Spinal Cord Injury Patients

Spinal cord injury patients can develop CRPS, particularly those with cervical and high thoracic injuries who experience loss of cardiovascular sympathetic innervation. 5

Key Clinical Considerations in SCI Patients

• Look for disproportionate pain that exceeds what would be expected from the initial SCI 5
• Neurogenic inflammation and autonomic dysfunction are hallmark features that can manifest in both conditions 5
• The same interventional treatments used for CRPS, including spinal cord stimulation, may be appropriate for SCI patients with persistent pain 5

Management Approach

Physical and occupational therapy are the cornerstone of CRPS treatment, with all other interventions serving to facilitate participation in rehabilitation. 1, 3, 6

First-Line Treatment

• Gentle stretching and mobilization 1
• Active range of motion exercises 1
• Sensorimotor integration training 1
• Progressive tactile stimulation 6
• Graded motor imagery and mirror therapy 4

Pharmacological Management

No drugs are FDA-approved specifically for CRPS, but the following may be used 6:

• Analgesics (NSAIDs, acetaminophen): To enable therapy participation 1, 6
• Gabapentinoids (gabapentin, pregabalin): For neuropathic pain 6
• Antidepressants (tricyclics, SNRIs): For neuropathic pain 3, 6
• Oral corticosteroids: To reduce inflammation and edema, particularly in early-stage CRPS 1, 6
• Bisphosphonates: May reduce pain intensity (low-certainty evidence) 7, 8
• Opioids: Should be added if other medications do not provide sufficient analgesia to allow participation in physical therapy 3

Interventional Treatments

For moderate to severe cases with sympathetic dysfunction 1, 3:

• Sympathetic nerve blocks (stellate ganglion blocks for upper extremity, lumbar sympathetic blocks for lower extremity) 1, 3
• Blocks should demonstrate progressive improvement with increasing duration of relief 1

For refractory cases 1, 3, 6:

• Spinal cord stimulation: Requires a trial before permanent implantation 1, 3
• Dorsal root ganglion stimulation: Emerging option for refractory cases 4

Psychological Support

• Cognitive behavioral therapy to reduce anxiety and avoidance behavior that perpetuate disability 1
• Stepped psychological interventions 1

Critical Treatment Pitfalls to Avoid

• Delaying physical therapy while waiting for pain to resolve worsens outcomes through disuse and pain upregulation 1
• Continuing sympathetic blocks indefinitely without documented progressive improvement 1
• Using peripheral somatic nerve blocks for long-term treatment 1
• Using sympathetic blocks for non-CRPS neuropathic pain 1
• Failing to document objective functional outcomes beyond pain scores 1

Prognosis and Follow-Up

Evaluating CRPS patients at least twice annually by a specialist is recommended due to high recurrence risk. 1 Early diagnosis and aggressive management are critical because long-term outcomes are improved when treatment is initiated soon after symptom onset 3, 6.