Complex Regional Pain Syndrome

Chronic neuroimmunological pain condition defined by:

Continuing pain that is disproportionate to any inciting event
Pain that is regional
Not specific to a dermatome or peripheral nerve territory.
With at least one finding from the following:
- Sensory
  Hyperaesthesia, allodynia.
- Motor/tropic
  ↓ range of motion or motor dysfunction.
- Sudomotor
  Oedema, sweating changes, asymmetry.
- Vasomotor
  Asymmetry in temperature or skin colour, or skin colour changes.
- Trophic findings
No other diagnosis that explains the symptoms

CRPS is divided into two subtypes:

Type I
No evidence of nerve injury. Previously known as reflex sympathetic dystrophy.
Type II
Evidence of nerve injury present. Previously known as causalgia.

Epidemiology and Risk Factors

Occurs in 0.5-2% of limb trauma.

Key risk factors:

Female > Male
Post-fracture

Pathophysiology

Poorly understood, but multifactorial process involving central and peripheral nervous systems:

Local tissue damage
Inflammation
Pain processing
Endocrine and autonomic
Immune

Aetiology

Clinical Manifestations

Diagnostic Approach and DDx

Investigations

Management

Non-pharmacological treatment is first line

Limited evidence for any particular therapy. Goals are to:

Restore function

↓ pain and disability

Improve quality of life

Prevention:

Avoid prolonged immobilisation
Vitamin C 500mg daily
Minimise tourniquet time

Non-pharmacological:

Graded Motor Imagery
Mirror therapy
Physiotherapy
Occupational therapy

Pharmacological:

Oral corticosteroids
Bisphosphonates
Gabapentinoids
Antidepressants

Refractory:

Sympathetic nerve blocks
Spinal cord stimulators
Dorsal root ganglia stimulation

Medical

Surgical

Anaesthetic Considerations

Marginal and Ineffective Therapies

Include:

Opioids
Worsening of pain due to central sensitisation.
Calcitonin
No effect.