Complex Regional Pain Syndrome

Complex Regional Pain Syndrome

By Lori Montgomery, MD, CCFP


Complex regional pain syndrome (CRPS) is a disorder that was known before as Reflex Sympathetic Dystrophy (say: ree-FLEKS sim-puh-THET-ik DIS-truh-fee). It has also been known by many other names, since it was first described by surgeons during the American Civil War.

Patients with this disorder have chronic pain in a certain area. It is most often in an arm or leg. It seems much more severe than you might expect from the original injury. For example, the pain may start with a minor sprain or a simple day surgery that would normally involve short-term, mild-to-moderate pain.

Two types of CRPS

CRPS is rare, but affected patients have very severe, disabling chronic pain. It is split into two types. The symptoms and treatment are the same. Type 1 does not involve any known nerve injury. Type 2 has a clear nerve injury as a source of pain.

Signs and symptoms

All patients with CRPS will have chronic pain in a certain region (most often one arm or leg). They will most often also have some of the following:

  • differences in temperature or skin colour in the affected limb
  • limits in the range of motion in the limb
  • very sensitive skin, similar to a bad sunburn
  • extreme amounts of sweat in the affected limb
  • swelling of one hand or one foot
  • tremors
  • weakness in one arm or leg
  • changes in the skin, hair, or nails on the affected side
  • decreased bone density (and possible fractures)


The cause of CRPS is unknown. What is clear is that the disease involves a malfunction in the body’s pain “alarm system”. Pain signals are made without a good reason.

Diagnostic tests

There are no specific diagnostic tests that help identify CRPS. It is diagnosed based on history and physical exam findings.

Treatment approach

Because CRPS is not common, there is little research on treatments that apply only to this condition. However, there are a number of treatments for chronic pain, which are commonly used in CRPS. There is no one treatment that addresses all of the symptoms of CRPS. Many patients take two or more of the following:

  • NSAIDs (anti-inflammatories such as ibuprofen or naproxen) can be useful if there is heat or swelling in the limb
  • tricyclic antidepressants (such as amitriptyline or nortriptyline)
  • gabapentin or pregabalin
  • tramadol or other opioid-like medications (such as morphine)
  • serotonin-norepinephrine reuptake inhibitors (such as venlafaxine or duloxetine)
  • calcitonin or bisphosphonates are useful to help maintain bone density and build bone

Injection therapies
There are injection therapies that have been used for CRPS for a number of years. While the research evidence for these therapies is scarce, they are an option for some patients. They include sympathetic nerve blocks and intravenous regional blocks. More invasive (and therefore higher risk) procedures that are being investigated include:

  • neurostimulation
  • intrathecal drug infusion
  • motor cortex stimulation

Non-drug therapies
Studies have shown that non-drug therapies can help to reduce pain levels and enhance pain coping. These include:

  • relaxation
  • meditation
  • activity pacing
  • cognitive behavioural therapy

These self-management strategies can help you to improve your function so you can do more and enjoy life more.

Some patients find things like acupuncture or transcutaneous electrical nerve stimulation (TENS) helpful. Physiotherapy can be useful to maintain range of motion, and prevent weakness in the limb. Aquatherapy is particularly useful, although many patients are sensitive to temperature and require a warm pool for exercise.


Complex regional pain syndrome: Treatment guidelines (third edition).Reflex Sympathetic Dystrophy Syndrome Association (RSDSA), 2006 Jun. p. 67