Complex regional pain syndrome (CRPS)

What is CRPS?
Complex regional pain syndrome (CRPS) is a chronic pain condition most often affecting one of the limbs (arms, legs, hands, or feet), usually after an injury or trauma to that limb. There are two similar forms, called CRPS-I and CRPS-II, with the same symptoms and treatments. CRPS-II (previously called causalgia) is the term used for patients with confirmed nerve injuries. Individuals without confirmed nerve injury are classified as having CRPS-I (previously called reflex sympathetic dystrophy syndrome). Some research has identified evidence of nerve injury in CRPS-I, so the validity of the two different forms is being investigated.

What are the symptoms of CRPS?
The key symptom is prolonged pain that may be constant and, in some people, extremely uncomfortable or severe. The pain may feel like a burning or “pins and needles” sensation, or as if someone is squeezing the affected limb. The pain may spread to include the entire arm or leg, even though the precipitating injury might have been only to a finger or toe. Pain can sometimes even travel to the opposite extremity. There is often increased sensitivity in the affected area, such that even light touch or contact is painful (called allodynia). People with CRPS also experience constant or intermittent changes in temperature, skin color, and swelling of the affected limb. This is due to abnormal microcirculation caused by damage to the nerves controlling blood flow and temperature. An affected arm or leg may feel warmer or cooler compared to the opposite limb. The skin on the affected limb may change color, becoming blotchy, blue, purple, pale, or red.

What causes CRPS?
CRPS is believed to be caused by damage to, or malfunction of, the peripheral and central nervous systems. In more than 90 percent of cases, this is the reason. The most common triggers are fractures, sprains/strains, soft tissue injury (such as burns, cuts, or bruises), limb immobilization (such as being in a cast), or surgical or medical procedures (such as needlestick). CRPS represents an abnormal response that magnifies the effects of the injury. In this respect it is like an allergy. Some people respond excessively to a trigger that causes no problem for other people.

How is CRPS diagnosed?
Currently there is no single diagnostic test to confirm CRPS. Diagnosis is based on the affected individual’s medical history and signs and symptoms that match the definition. But because several other conditions can cause similar symptoms, careful examination is important. Since most people improve gradually over time, diagnosis may be more difficult later in the course of the disorder.
Testing also may be used to help rule out other conditions, such as arthritis syndromes, Lyme disease, generalized muscle diseases, a clotted vein, or small nerve fiber polyneuropathies (such as from diabetes), because these require different treatment. The distinguishing feature of CRPS is usually a history of earlier injury to the affected area, as most of these other conditions are not triggered by injury. Individuals without a history of injury should be carefully examined to make sure that another treatable diagnosis is not missed.

What are the treatments for CRPS?
Rehabilitation therapy: An exercise program to keep the painful limb or body part moving can improve blood flow and lessen the circulatory symptoms. Additionally, exercise can help improve the affected limb’s flexibility, strength, and function. Rehabilitating the affected limb also can help to prevent or reverse the secondary brain changes that are associated with chronic pain. Occupational therapy can help the individual learn new ways to work and perform daily tasks.
Biofeedback: This is a treatment that teaches a patient to become aware of processes that are normally thought to be involuntary inside of the body (such as blood pressure, temperature, and heart rate control). This method enables you to gain some conscious control of these processes, which can influence and improve your level of pain. A better awareness of one’s body teaches one to effectively relax, and this can help to relieve chronic pain.
Medications: Several different classes of medication have been shown to be effective for CRPS, particularly when used early in the course of the disease. Drugs to treat CRPS include can include non-steroidal anti-inflammatory drugs, corticosteroids (used mostly in the early stages of CRPS), Neuropathic medications (such as gabapentin, lyrica, amitriptyline, nortriptyline, and duloxetine), opioids (in early stages), N-methyl-D-aspartate (NMDA) receptor antagonists, topical local anesthetic creams and patches. A combination of these may be most effective.
Sympathetic nerve block: This therapy targets the sympathetic nervous system, a series of nerves that spread out from your spine to your body to help control several involuntary body functions, or body functions that you have no control over. These include blood flow, digestion, and sweating. Sympathetic nerve block can be used to diagnose or treat pain involving the nerves of the sympathetic nervous system. These blocks are typically performed in a series.
Spinal Cord Stimulation (SCS): A surgically implanted electrical device which decreases the perception of pain by targeting the spinal cord and brain pain processing centers. Before the surgical implantation, a one week minimally invasive trial is performed to see if this device will help you long-term. If there is significant pain decrease and an increase in functional ability during the trial, you would be a candidate to have a permanent SCS device implanted.