FAQs on Complex Regional Pain Syndrome (CRPS)


Complex regional pain syndrome (CRPS) is a chronic pain condition that is thought to be the result of dysfunction in the peripheral and/or central nervous systems. Also called reflex sympathetic dystrophy (RSD), CRPS has an incidence of 3 per every 10,000 individuals, and affects women three times more than men. The peak incidence is in persons aged 55 to 75 years, but it can occur in younger people, as well as the elderly.

What are the types of CRPS?

There are two types of CRPS: I and II. In CRPS I, the onset of symptoms is triggered by nerve and/or tissue injury. Patients experience drastic color and temperature changes of the skin over the affected body part or extremity. The pain is described as an intense burning with extreme sensitivity and swelling. CRPS II causes the same symptoms, but they are not clearly associated with any type of nerve or tissue injury.

What are the symptoms of CRPS?

The main symptom of CRPS is an intense, continuous pain that is more severe than what is expected of the injury or illness. The pain gets worse over time, instead of improving, and affects only one of the extremities, such as one arm, one hand, one leg, or one foot.

Associated symptoms include increased skin sensitivity, changes in hail and/or hair growth patterns, stiffness and swelling of the affected joints, skin color changes, and warmth or coolness of the affected body part. Many patients have impaired mobility of the affected extremity.

What happens during the course of the disease?

The symptoms of CRPS vary in length and severity. Pain often travels to the opposite extremity, and can spread the entire length of the leg or arm, even when the injury occurred only in the toe or finger. Many experts believe CRPS occurs in 3 stages. These include:

  • Stage 1 – Lasts from 1 to 3 months, and is characterized by severe pain, muscle spasms, skin color and temperature changes, and joint stiffness.
  • Stage 2 – Lasts from 3 to 6 months and is characterized by worsening pain intensity, decreased hair/nail growth, tissue swelling, joint stiffness, and weakened muscles.
  • Stage 3 – After CRPS symptoms are present for 6 to 9 months, the syndrome progresses to the point where the skin, tissue, and bone changes are not reversible. The pain persists and often affects the entire limb. During this stage, there is marked muscle atrophy (wasting), limited mobility of the body part, and muscle/tendon contractions.

What causes complex regional pain syndrome?

The exact cause of CRPS is not known, but experts believe the sympathetic nervous system plays a key role in sustaining the pain. One recent theory suggests that the pain receptors of the arm/leg become responsive to nervous system messengers called catecholamines.

These messengers can activate pain pathways long after the initial tissue or nerve injury. Another respected theory is that CRPS is the result of the immune system response, which leads to all the inflammatory symptoms associated with the disease.

How do doctors treat CRPS?

There is no known cure for CRPS, but some patients do improve with time. Treatment focuses on relieving pain and associated symptoms. Options include:

  • Stellate ganglion block – To provide pain relief to the region supplied by a group of nerves, the injections are performed under x-ray guidance (fluoroscopy). For CRPS of the arms or hands, the doctor injects a long-acting anesthetic in the front of the neck into the area near the sympathetic chain. After the block, there may be temporary numbness, warmth, and/or weakness of the extremity for a few hours. In a recent clinical study of this block, 76% of patients reported improvement in pain, with 40% having complete symptom relief.
  • Surgical sympathectomy – In this procedure, the doctor destroys the nerves that supply the extremity by using coagulation or a destructive agent, such as phenol or absolute alcohol. This procedure is reserved for patients who do not respond to a sympathetic or stellate ganglion nerve block. In studies of patients with CRPS who had this procedure, most reported more than 50% pain reduction with a notable decrease in pain scores. Around 77% of study participants reported willingness to have the procedure again.
  • Intrathecal drug pump – The doctor implants a small device near the spine to deliver strong pain medicine into the spinal fluid. With this route bypassing the gastrointestinal tract, the patient does not have unpleasant side effects associated with oral pain medicine administration.
  • Spinal cord stimulation – To stimulate the spinal cord, the doctor implants a small device near the spinal cord. The unit delivers small bursts of electric current to the spine. In a recent clinical study of 84 patients over 12 years, 41% had more than 30% pain relief, and at follow-up years later, 63% of the implant patients still used the device.