What Is Complex Regional Pain Syndrome (CRPS)?

Pain that keeps burning long after an injury should have healed, and skin that changes color or temperature without warning, are hallmarks of complex regional pain syndrome (CRPS), formerly known as reflex sympathetic dystrophy (RSD). CRPS typically develops in an arm or leg after an injury, surgery, or even a minor sprain, producing pain that’s far more intense and longer lasting than the original injury would suggest. Summit Spine & Joint Centers works with patients through diagnosis and treatment for complex regional pain syndrome, from the confusing early symptoms through long-term pain management.

What are the symptoms of complex regional pain syndrome?

Complex regional pain syndrome symptoms fall into a few consistent categories, though not every patient experiences all of them, and which symptoms are most prominent often shifts over the course of the disease.

• Pain is usually the most striking feature: A constant burning or throbbing sensation that’s disproportionate to whatever caused it. Many patients also experience allodynia, an extreme sensitivity in which a light touch, a change in temperature, or even a passing sound can trigger significant pain in the affected area.
• Skin and circulation changes are common: The affected limb may swell, change color (looking blotchy, red, white, or blue), or feel noticeably warmer or cooler than the rest of the body. Over time, the skin can become shiny or thin, and hair and nail growth in the area may speed up or slow down.
• Movement and muscle symptoms often follow: Spasms, weakness, tremor, and joint stiffness limit range of motion. In longer-standing cases, some patients develop measurable changes in bone density in the affected limb, along with muscle weakness and coordination difficulties that make the limb harder to rely on.
• Sleep disruption and difficulty concentrating can compound the physical symptoms and make daily life harder to manage. Symptoms can change with treatment, medication, activity level, and even stress, which is part of why CRPS can be confusing for patients to track and describe to a physician.

What Are the Types of CRPS?

There are two recognized types of CRPS, and the distinction comes down to whether a specific nerve injury can be identified.

• CRPS Type I, formerly called reflex sympathetic dystrophy, develops after an injury without a confirmed nerve injury, such as a fracture, sprain, surgery, or a period of immobilization. This is by far the more common form, accounting for roughly 90 percent of diagnosed cases, according to the Mayo Clinic. In some cases, no clear triggering injury can be identified at all.
• CRPS Type II, previously known as causalgia, follows a confirmed injury to a specific nerve, such as one that can occur during a surgical procedure or a traumatic accident.

Both types are managed similarly. If you were diagnosed with RSD in the past rather than CRPS, that’s the same condition under an older name, now generally classified as CRPS Type I.

How Is CRPS Diagnosed?

There’s no single test that confirms CRPS on its own. Diagnosis is based mainly on a physical exam and a patient’s history of symptoms and their timeline relative to an injury, according to the Mayo Clinic. From there, a physician may use supporting tests to build the picture and rule out other conditions, including bone scans to check for changes in bone density, sweat tests comparing perspiration between limbs, X-rays, and MRI imaging.

Because CRPS shares symptoms with other nerve and circulatory conditions, and because there’s no blood test that confirms it, diagnosis can take time and sometimes requires seeing a specialist familiar with the condition. Bringing a clear record of when symptoms started and how they’ve changed can help a physician reach a diagnosis faster.

Which Parts of the Body Does CRPS Affect?

CRPS most often develops in a hand, arm, foot, or leg, usually starting at or near the site of the original injury. From there, it can involve the nerves, skin, blood vessels, muscles, and bones of the affected limb, which is why symptoms show up in so many different ways at once.

Less commonly, CRPS can affect other areas of the body, including the face, shoulders, back, or eyes. A smaller number of patients also experience what’s sometimes called mirror pain, in which symptoms appear on the opposite, uninjured limb.

When the nerves near an injury are overstimulated, they release chemicals that widen nearby blood vessels, allowing fluid to move into the surrounding tissue. That process, sometimes called neurogenic inflammation, is part of why the skin often looks red, feels warm, and becomes more sensitive to pain as the condition develops.

Does CRPS Spread To Other Areas?

CRPS can spread beyond where it first appears, though the pattern varies from patient to patient. The most common pattern is spread within the same limb, extending from the original injury site to involve more of the arm or leg. Spreading to a different limb, including the opposite side of the body, is reported less often.

Because spread is hard to predict, our specialists track how CRPS is progressing at each visit rather than assuming a fixed course, and adjust the treatment plan as symptoms change.

Who Is Most at Risk for CRPS?

CRPS can develop in anyone, but certain patterns show up consistently in the research:

• Women are affected roughly three times more often than men, according to a landmark study following nearly 900 patients (Veldman et al., 1993). 
• Most people are diagnosed in their 30s to 50s, with the average age at diagnosis around 40, per Cleveland Clinic. 
• Cleveland Clinic also notes that an estimated 66 to 80 percent of diagnosed cases occur in people of European ancestry, though the reasons for that pattern aren’t fully understood.
• CRPS is uncommon in children and typically follows a milder course when it does occur. Pediatric cases tend to improve within several months with treatment, according to the National Institute of Neurological Disorders and Stroke (NINDS), though symptoms can recur, and a growing number of cases are being reported in teenagers and young adults, particularly girls.
• Certain injuries carry a higher risk than others. Fractures, especially of the wrist or ankle, are among the most common triggers, along with surgery, sprains, and prolonged immobilization of a limb. 
• Other risk factors noted by Cleveland Clinic include nerve conditions such as diabetic neuropathy, smoking, and a history of chemotherapy.

How Common Is CRPS?

Researchers estimate that CRPS develops in about 2 to 5 percent of people who sustain a peripheral nerve injury, according to NINDS. That figure applies to nerve injuries, a smaller and more defined group than “all injuries” broadly, which is worth pointing out since online estimates of how many people are affected by CRPS in the United States vary widely, often because that percentage gets applied to the wrong starting number.

CRPS Type I is the far more common of the two types, making up around 90 percent of diagnosed cases. Because CRPS is relatively rare and can be difficult to recognize, it’s also likely underdiagnosed, particularly in milder cases that improve before a diagnosis is ever made.

What Is the Outlook for CRPS, and How Is It Treated?

Early diagnosis and treatment give patients the best chance at a good outcome. In a long-term study of patients in Olmsted County, Minnesota, about 74 percent experienced complete resolution of their CRPS symptoms (Sandroni et al.), though recurrence after remission is possible in an estimated 10 to 30 percent of cases, according to Cleveland Clinic. Every patient’s course is different, and we’re cautious about predicting how any individual case will progress, since CRPS doesn’t follow one fixed timeline.

Complex regional pain syndrome treatment typically combines several approaches rather than relying on a single fix. Physical and occupational therapy, often involving guided exercise and desensitization techniques, helps maintain movement and function in the affected limb. Medications range from over-the-counter anti-inflammatories to prescription nerve pain medications, corticosteroids, and, for select patients, low-dose opioids or IV ketamine. Psychological support, including cognitive behavioral therapy, biofeedback, and support groups, can help patients cope with the toll of living with chronic pain.

For patients who need more targeted relief, interventional pain management techniques, including sympathetic nerve blocks, can help interrupt the pain signals driving CRPS. In more severe or treatment-resistant cases, options like spinal cord stimulation or an implanted drug pump may be considered. You can find more detail on the procedures we offer on our treatments page.