Complex regional pain syndrome

Overview

Complex Regional Pain Syndrome (CRPS) is a chronic pain condition typically affecting a limb, most often after an injury, surgery, stroke, or heart attack. The pain experienced is often out of proportion to the initial injury. CRPS is characterized by prolonged or excessive pain, along with changes in skin color, temperature, swelling, and motor function. It is divided into two types: CRPS-I (formerly reflex sympathetic dystrophy) occurs without confirmed nerve damage, and CRPS-II (formerly causalgia) occurs with confirmed nerve injury. Although CRPS can improve over time, early diagnosis and intervention are key to managing symptoms and preventing long-term disability.

Causes

The exact cause of CRPS is not fully understood, but it is believed to involve abnormal responses by the peripheral and central nervous systems. Potential triggers include:

• Trauma: Fractures, sprains, or soft tissue injuries

• Surgical procedures: Especially orthopedic surgeries involving limbs

• Infections or inflammation: In the affected limb

• Nerve damage: In CRPS-II, direct nerve injury leads to the syndrome

• Immune response abnormalities: Autoimmune mechanisms may contribute to inflammation and pain sensitivity

Not everyone who experiences an injury will develop CRPS, indicating individual susceptibility factors may play a role.

Symptoms

Symptoms of CRPS can vary in intensity and duration but typically affect one limb and are often progressive. Common features include:

• Continuous burning or throbbing pain: Usually in the arm, leg, hand, or foot

• Sensitivity to touch or cold: Even light touch may provoke severe pain (allodynia)

• Swelling of the affected limb

• Skin color changes: May alternate between pale, red, blue, or blotchy

• Temperature changes: Affected area may feel warmer or cooler than the opposite limb

• Changes in skin texture: Shiny, thin, or sweaty skin

• Motor dysfunction: Including tremors, muscle spasms, weakness, or decreased range of motion

• Nail and hair growth changes: Increased or decreased growth rate

Symptoms often worsen over time and may spread to other areas of the body in some individuals.

Diagnosis

There is no single test for CRPS; diagnosis is made based on clinical criteria and exclusion of other conditions. Diagnostic steps include:

• Medical history and physical exam: Focused on the pattern and nature of pain and associated symptoms

• Budapest Criteria: Widely accepted clinical guidelines used to diagnose CRPS based on sensory, vasomotor, sudomotor, and motor/trophic changes

• Imaging tests:

  • Bone scan may show abnormal bone metabolism

  • X-rays or MRI can detect bone loss or tissue changes

• Sympathetic nerve block: May be used diagnostically if pain temporarily resolves

• Laboratory tests: Used to rule out infections, arthritis, or other systemic conditions

Treatment

Early and individualized treatment is essential for managing CRPS. A multidisciplinary approach often yields the best outcomes. Treatment options include:

• Medications:

  • NSAIDs for pain and inflammation

  • Anticonvulsants (e.g., gabapentin) and antidepressants (e.g., amitriptyline) for neuropathic pain

  • Corticosteroids to reduce inflammation

  • Bisphosphonates or calcitonin for bone involvement

  • Topical agents like lidocaine or capsaicin

• Physical therapy: To improve mobility, function, and blood flow to the affected area

• Occupational therapy: Helps with activities of daily living and coping strategies

• Psychological support: Cognitive-behavioral therapy (CBT) to manage chronic pain, anxiety, or depression

• Nerve blocks: Local anesthetic injections to interrupt pain signals

• Spinal cord stimulation: An implanted device that delivers electrical impulses to reduce pain in refractory cases

• Mirror therapy and graded motor imagery: Useful for desensitization and improving motor control

Prognosis

The prognosis of CRPS varies. Some individuals recover fully, especially when diagnosed and treated early. However, others may experience persistent pain and disability. Chronic cases can lead to long-term complications such as joint stiffness, muscle wasting, or emotional distress. Early, aggressive, and multidisciplinary treatment improves the chances of symptom control and functional recovery. Regular follow-up and personalized care are essential for managing ongoing symptoms and maintaining quality of life.