Introduction

Complex Regional Pain Syndrome (CRPS) is a chronic pain condition that usually affects one limb (arm, leg, hand, or foot), often after an injury, surgery, stroke, or heart attack. CRPS is characterized by prolonged or excessive pain and changes in skin color, temperature, and/or swelling in the affected area. It is considered a disorder of the nervous system, particularly involving abnormal responses of peripheral and central nerves.

CRPS is divided into two types:

• CRPS Type I: Occurs without a confirmed nerve injury (formerly called Reflex Sympathetic Dystrophy).
• CRPS Type II: Occurs with a confirmed nerve injury (formerly called Causalgia).

Symptoms

CRPS symptoms can vary in intensity and may spread from the initial injury site. They include:

1. Pain

• Severe, burning, or aching pain that is disproportionate to the initial injury.
• Pain may spread beyond the original injury site.

2. Skin Changes

• Color changes: blotchy, purple, pale, or red skin.
• Temperature changes: affected limb may feel warmer or colder than the other limb.

3. Swelling and Edema

• Swelling of the affected limb, sometimes accompanied by stiffness.

4. Sensory Changes

• Hyperalgesia: increased sensitivity to pain.
• Allodynia: pain from stimuli that usually aren’t painful (e.g., light touch).

5. Motor Dysfunction

• Weakness, tremors, or difficulty moving the affected limb.

6. Other Symptoms

• Changes in hair or nail growth.
• Joint stiffness.
• Muscle atrophy in severe or prolonged cases.

Causes

The exact cause of CRPS is not fully understood, but it typically develops after trauma. Possible mechanisms include:

• Nerve injury or dysfunction: Damage or abnormal function of peripheral or central nerves.
• Immune system involvement: Inflammatory responses may exacerbate pain and swelling.
• Abnormal sympathetic nervous system activity: Overactive nerve signaling may cause vasodilation, sweating, and temperature changes.
• Genetic factors: Some evidence suggests certain individuals may have a predisposition.

Common triggers: fractures, sprains, surgery, burns, or even minor injuries.

Diagnosis

There is no single test for CRPS; diagnosis is primarily clinical, based on history, physical examination, and exclusion of other conditions.

Diagnostic criteria (Budapest Criteria) include:

1. Continuing pain disproportionate to the initial injury.
2. At least one symptom in three of four categories:
   • Sensory: hyperesthesia, allodynia.
   • Vasomotor: temperature or color changes.
   • Sudomotor/Edema: swelling or sweating changes.
   • Motor/Trophic: decreased range of motion, weakness, hair/nail changes.
3. At least one sign in two or more of these categories observed by the physician.
4. No other condition explains the symptoms.

Additional tests (to support diagnosis or rule out other conditions):

• Bone scans.
• MRI or X-rays (may show bone changes in chronic CRPS).
• Thermography to detect temperature differences.
• Nerve conduction studies.

Treatment

CRPS treatment is most effective when started early. The goal is to relieve pain, restore function, and improve quality of life.

1. Medications

• Pain relievers: NSAIDs, acetaminophen, opioids (short-term).
• Neuropathic pain agents: gabapentin, pregabalin, tricyclic antidepressants.
• Corticosteroids: reduce inflammation in acute stages.
• Bisphosphonates: sometimes used for bone-related symptoms.

2. Physical and Occupational Therapy

• Gradual, guided exercise to maintain mobility and function.
• Desensitization therapy for hypersensitive skin.

3. Nerve Blocks and Injections

• Sympathetic nerve blocks may reduce pain temporarily.

4. Psychological Support

• Cognitive-behavioral therapy to manage chronic pain and associated anxiety or depression.

5. Advanced Treatments (for refractory cases)

• Spinal cord stimulation.
• Intrathecal pain pumps.
• Ketamine infusions.

Prevention

While CRPS cannot always be prevented, early intervention after injury can reduce risk:

• Prompt treatment of fractures, sprains, or surgical injuries.
• Gentle movement and physiotherapy after injury or surgery.
• Pain management to prevent overactivation of the nervous system.
• Monitoring for early signs (swelling, color changes, severe pain) and seeking medical attention promptly.

CRPS is a complex, often disabling condition, but early recognition and a multidisciplinary treatment approach can significantly improve outcomes.