What Is Complex Regional Pain Syndrome (CRPS)?

Complex regional pain syndrome, or CRPS, is an umbrella term that describes long-term pain and inflammation occurring after an injury or medical event, such as surgery, a stroke, or a heart attack. People with CRPS experience above-average pain levels. CRPS was previously known as reflex sympathetic dystrophy (RSD) or causalgia. 

CRPS is rare, with only 26 out of 100,000 people developing it, or about 86,000 people in the United States. The exact cause of this condition is unknown, although people with a uterus and those with arthritis, fibromyalgia, or neuropathic inflammation are at a higher risk of developing CRPS. 

Four subtypes of CRPS exist, including type I and type II, warm, and cold. CRPS symptoms vary from person to person. You may experience burning pain, changes in skin color, temperature, or swelling on the arm or leg below the injury site. CRPS can be short-term or permanent. 

While there’s no cure for CRPS, getting immediate treatment can help make it manageable and prevent serious complications.  

Types of CRPS

Different classifications exist for CRPS. First, CRPS is divided into type I and type II. Then it is divided into warm and cold based on temperature sensation, where the acute phase is the warm phase and the chronic phase is the cold phase. Therefore, it is possible to have type 1 warm CRPS, type 1 cold CRPS, type 2 warm CRPS, and type 2 cold CRPS.

Both type I and II generally occur after trauma or physical injury. However, the primary difference between the two is the presence of a nerve injury, which is absent in type I but present in type II.

Type I CRPS (CRPS-1)

Type I CRPS develops from an injury or other painful event. Common events associated with Type 1 CRPS include surgery, stroke, and heart attack. It generally causes symptoms in one or more extremities, potentially leading to limb immobility. Type 1 CRPS represents 90% of cases. 

Type II CRPS (CRPS-2)

Type II CRPS, or causalgia, develops after a nerve injury. People with this condition may face severe symptoms depending on the damage or injury to their peripheral nerves. The peripheral nerves innervate your limbs, meaning they send messages from your brain to the rest of your body.

Warm CRPS

This CRPS subtype occurs among people with acute or short-term CRPS. Warm CRPS leads to a warmer body temperature with a reddish hue near the injury site due to increased blood flow to the affected area.

Cold CRPS

Cold CRPS typically develops in people with chronic or long-term CRPS. The patient’s injury site may feel “cooler,” with skin appearing blue.

Complex Regional Pain Syndrome Symptoms 

People with CRPS may experience various symptoms, including:

• Pain: You may experience burning or throbbing pain, which starts in the affected area and radiates outward. The pain may travel to your arms, legs, hands, or feet over time. 
• Skin sensitivity: You may develop allodynia on the surface of your injury. This condition causes your skin to be painful to light touch or typical physical contact.
• Changes in skin color: Your arm or leg may feel much warmer or cooler than the limbs without CRPS. Your skin may also change colors, appearing red, blue, purple, or gray. Skin color changes indicate a change in blood flow.
• Changes in skin texture: In addition to skin color changes, a lack of proper oxygen and nutrients in the affected area may lead to skin becoming thin and shiny or thick and scaly. 
• Nail and hair growth: Nerve damage can cause your hair and nails to grow rapidly.
• Sweating: Nerve damage can also contribute to excessive sweating.
• Stiffness: If you’re experiencing pain, you probably aren’t moving the injured limb. However, a lack of mobility can cause joint stiffness, worsening CRPS symptoms. 
• Bone thinning or excess bone growth: CRPS may affect the bone marrow (the spongey area in the center of your bones), leading to bone thinning. In rare instances, the condition may cause bones to become rough or enlarged in the injury area.
• Muscle weakness: With complex regional pain syndrome, you cannot move affected limbs as often, leading to progressive muscle weakness. 

Causes

Complex regional pain syndrome is a neuropathic pain disorder that arises due to trauma to your nerves or injury to an affected limb. As noted above, types I and II CRPS have different causes. Type I originates from illness or injury, while type II occurs from nerve trauma. However, the exact mechanism that occurs in your body is unknown. 

Some researchers believe CRPS may occur because the sympathetic nervous system malfunctions after injury. The sympathetic nervous system controls your “fight or flight” responses in the body.

Risk Factors for Complex Regional Pain Syndrome

Certain risk factors may increase your chances of developing CRPS, including:

• Being older than 60
• Having a uterus (a reproductive organ in people assigned female at birth)
• Experiencing an exposed fracture, which is when a bone breaks and punctures your skin
• High-impact injuries (i.e., fracture of long bones, loss of consciousness, motor vehicle injuries, etc.)
• Low-impact injuries (i.e., fall from your height)
• Presence of comorbidities (having two or more diseases or medical conditions)
• History of mental health disorders
• Type of fracture (i.e., closed, exposed, occurring with other fractures, or occurring on its own)
• Type of treatment used for your injury or fracture
• Number of manipulations (manual or forced pressure on the injury site)

Diagnosis

There’s no specific diagnostic test or procedure healthcare providers use to diagnose complex regional pain syndrome. Instead, a healthcare provider, such as a neurologist (a doctor specializing in the nervous system), orthopedist (a doctor specializing in the musculoskeletal system), or a plastic surgeon, will diagnose the condition by reviewing your medical history, administering a physical exam, and ordering various tests.

Your healthcare provider may request the following diagnostic tests for complex regional pain syndrome:

• Nerve conduction studies: These tests measure the electrical activity in your muscles and nerves.
• Ultrasound: An imaging test that uses sound waves to develop pictures of your organs, tissues, and other structures within your body.
• Magnetic resonance imaging (MRI): An imaging machine that produces 3D images of the organs and tissues in your body so your provider can view them.
• Triple-phase bone scans: A procedure using small amounts of radioactive materials and a special camera to create images of your bones.

Stages of Complex Regional Pain Syndrome

Diagnostic tests can help your healthcare provider determine what type and stage of complex regional pain syndrome you have.

Below are the three stages of CRPS and the symptoms that accompany them.

• Stage 1 (acute): You may experience symptoms like burning pain and have signs of swelling, redness, or skin irritation but no bone issues.
• Stage 2 (subacute): Your edema (swelling) worsens, the skin thickens, and muscles weaken. 
• Stage 3 (chronic): At the most aggressive stage of CRPS, you may have less mobility and experience shortening of muscles, tendons, skin, and soft tissue (contractures), thin and shiny skin (skin atrophy), and bone mineral loss. 

Treatments for CRPS

There’s no known cure for complex regional pain syndrome. Yet, there are treatments available to help you manage the symptoms. 

CRPS treatments are generally more effective when you start them as soon as you begin to experience symptoms.

Physical Therapy

Physical therapy is a type of exercise rehabilitation that can be a crucial aspect of managing CRPS. This is because it is important to keep affected limbs moving to improve blood flow, thereby lessening CRPS symptoms. Rehabilitation can increase your strength, flexibility, and function. Occupational therapy, another type of rehabilitation, can also help you adapt new ways to stay active and resume daily activities.

Behavior Changes

Elevating your affected arms or legs can help reduce swelling and pain when resting or sleeping, as it helps blood that may be pooling in your extremities move back toward your heart for recirculation. You can also try compression sleeves or socks to promote blood flow and relieve swelling.

Graded Motor Imagery (GMI)

This is a non-invasive therapy that treats phantom limb pain (PLP), or the perception of pain in a limb that is no longer there, through mental exercises to separate movement and pain. While CRPS doesn’t affect missing limbs, GMI can help “retrain” your brain through visualization, which can help you navigate situations when CRPS may cause you to feel pain.

Psychotherapy

If you have severe CRPS, you might develop secondary mental health problems, such as anxiety, depression, and even post-traumatic stress disorder (PTSD). These conditions can worsen CRPS, making it a challenge for some people to seek proper medical care or go through rehabilitation. Psychotherapy can help you cope and figure out your next steps for recovery.

Prescription Medications 

Some types of medications can help relieve CRPS symptoms, such as neuropathic pain, immobility, spasms, or sleep troubles. These include:

• Anticonvulsants
• Bisphosphonates
• Corticosteroids
• Muscle relaxants
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Opioids
• Serotonin-norepinephrine reuptake inhibitors (SSRIs)
• Tricyclic antidepressants
• Ketamine infusions
• Lidocaine 

Medication needs vary depending on what is contributing to your pain, where it is occurring, and what symptoms you’re experiencing. A combination of medications may be prescribed by your healthcare provider. You may have to undergo some trial and error before finding what helps you, so regularly update your provider on how you’re feeling and if you are experiencing any side effects.

Prevention 

Since there’s no known cause of complex regional pain syndrome, there’s no true way to avoid it. However, a 2021 study suggested that taking 500 to 1,000 milligrams per day of vitamin C supplements may reduce the risk of developing type I CRPS. Still, there’s a need for additional research to confirm this effect.  

Early and aggressive treatment of CRPS may prevent painful flare-ups. The early treatment stage is within six months of CRPS symptom onset. Research reveals that people with CRPS who took bisphosphonates (a type of drug used to slow bone loss) within the first three to six months of CRPS symptoms had a significant improvement in symptoms.

Complications

CRPS can be a short- or long-term medical condition. If you have chronic CRPS, you may have a co-occurring illness or disease or be at risk of developing one.

Conditions that can occur as a result of chronic CRPS include.

• Adrenal insufficiency: This condition occurs when your adrenal glands don’t make enough of the hormone cortisol. A 2017 study revealed that people with CRPS type I were more likely to have hormonal imbalances due to a disruption in the hypothalamic-pituitary-adrenal (HPA) axis. This disruption can damage your adrenal glands.
• Fixed dystonia: This condition causes muscle contractions that lead to repetitive twisting movements or abnormal postures. Fixed dystonia is a secondary condition to CRPS, affecting about 25% of people with CRPS.
• Gastrointestinal problems: Some CRPS patients have issues with their gastrointestinal tract. An 2013 study suggested that CRPS may lead to digestive issues like nausea and changes in GI microbial flora.

Living With Complex Regional Pain Syndrome

Research suggests that most people with CRPS recover and have little pain after one year. In fact, a 2017 research article revealed that the resolution of CRPS ranged between 74% in the first year of symptom onset to 36% after six years.

Fortunately, CRPS isn’t a life-threatening disease, although it can affect your quality of life. Return-to-work rates vary among people with CRPS, with 31% describing a permanent inability to work and 31% having a partial inability to work.

If you live with CRPS, know that you don’t have to cope with this condition by yourself. Take care of yourself by joining support groups, seeking therapy, and spending time with friends and loved ones.