Complex regional pain syndrome (CRPS) refers to a chronic condition affecting the nerves and blood vessels of one or more extremities. It is distinguished by extremely unpleasant burning sensations, swelling, sweating, color changes, and other distressing symptoms.
Causalgia is a rare pain syndrome related to partial peripheral nerve injuries. The peripheral nervous system encompasses nerves that extend from the central nervous system of the brain and spinal cord to serve limbs and organs.
Severe cases are called major causalgia. Minor causalgia describes less severe forms, similar to reflex sympathetic dystrophy (RSD). RSD includes muscular and joint pain symptoms, and changes in bone density.
Causalgia is usually caused by brachial plexus injuries, involving nerves that run from the neck to the arm. The disruption of neural signals causes pain and increased release of the neurotransmitter norepinephrine, which causes vascular symptoms.
The cause of CRPS is not known. The condition likely results from several factors. It may involve overactivity of the sympathetic nervous system, which directs automatic body functions that a person cannot control. Inflammation also may play a role in the disorder.
Minor or severe trauma increases the risk of CRPS:
- Penetrating injury
- Crush injury
- An injection into the muscle
- Blood draws
- Diabetic neuropathy
- Multiple sclerosis
If you have any of these symptoms do not assume it is due to CRPS. These symptoms may be caused by other conditions.
The upper extremities, particularly the hands, are most commonly affected. Symptoms progress and may vary during the course of the condition. Pain may spread from one side of the body to another. Many doctors describe symptoms in terms of stages.
Tell your doctor if you have any of these:
Within Hours or Days After Injury
Symptoms may include:
- Deep aching or burning pain, typically more severe than expected from the injury
- Sensitivity to touch or even a light breeze
- Swelling in the arm or leg
- Unusual sweating
- Excessively warm or cool skin
- Hair and nails changes
- Symptoms may increase with stress and worsen over time.
3-6 Months After Injury
Symptoms may include :
- Burning pain moves to above and below the initial injury
- Swelling in the arm or leg hardens
- Muscle spasms or weakness develop
- Extremity becomes cold
- Hair growth slows
- Nails become brittle or crack
Six Months or Later After Injury
Symptoms may include :
- A pale, blue, and/or shiny appearance to the skin
- Limited joint movement
- Muscle loss
Your doctor will ask about your symptoms and medical history and perform a physical exam. To diagnose CRPS, the doctor uses four criteria:
- An initial traumatic or painful event to a limb, or immobilization of the limb for a period of time
- Continuing pain in the limb that is out of proportion to any stimulus (eg, pain with even light touch)
- History of swelling, changes in skin blood flow, or temperature only in the affected limb
- No other cause for the symptoms
Tests may be ordered to rule out other conditions. Your doctor may refer you to a pain specialist for further evaluation and management.Tests may include the following:
- X-ray —a test that uses radiation to take a picture of structures inside the body, especially bones
- Bone scan —a special imaging test to check for early changes in bones
- Thermogram—to measure heat radiating from the body, which may be diminished in CRPS extremity
- Quantitative sudomotor axon reflex test (QSART)—a test that measures problems with the autonomic nervous system, like sweating
- Nerve conduction studies —test that measures the speed and degree of electrical activity in a nerve to determine if it is functioning normally
- Electromyography —measures and records the electrical activity that muscles generate at rest and in response to muscle contraction
Treatment aims to relieve pain and improve function. Visit the doctor as soon as possible. Early therapy may lead to better outcomes. In some cases, the condition goes away on its own; this is more common in children.
Medical therapy is usually ineffective.
Sympathetic block, which involves a series of localized anesthetic injections to block certain signals from the sympathetic nervous system, brings lasting relief to 18 percent to 25 percent of patients.
Surgical sympathectomy, or surgery to block certain nerve signals, brings complete relief to more than 80 percent of patients and relief of sympathetic symptoms to 90 percent. Similar results are found among patients with reflex sympathetic dystrophy.
Techniques used include anterior thoracic, thoracic endoscopy, percutaneous radiofrequency and supraclavicular.
The risk of significant complication is approximately 5 percent.
Risks include collapsed lung, pain in the rib area, spinal cord injury, and Horner’s syndrome. Symptoms of the syndrome include drooping eyelid, contracted pupils, absence of sweating and receding eyeball.
Treatment options include:
- Physical therapy—Active and passive exercises help maintain function. Exercising in a warm pool may feel better than exercising on land.
- Mirror box therapy—With this therapy, you place your affected hand or foot in a box, which has a mirror on one side. While moving your limb inside of the box, you move your unaffected limb in front of the mirror. To your brain, it appears that you are moving your painful limb easily and without discomfort. Mirror therapy may help to reduce pain and improve motor function in people who have CRPS due to stroke.
- Transcutaneous nerve stimulation (TENS)—A device worn on the skin surface creates a tingling sensation and may relieve pain in some cases.
- Anti-anxiety medications, low-dose antidepressants, and drugs used to treat epilepsy
- Pain medications, such as narcotics
- Other drugs to control symptoms
- Sympathetic nerve block—The injection of drugs that prevent the transmission of signals along sympathetic nerves may temporarily relieve pain in some cases.
- Sympathectomy—If the nerve block is successful, a surgeon can permanently destroy sympathetic nerves. In some cases, surgery can worsen symptoms.
- Psychological support— Long-term pain often leads to depression or anxiety . Counseling is often required to help patients deal with chronic pain and loss of function.
Quick mobilization after surgery or injury can help minimize the risk of CRPS in the affected extremity. Other steps that might be helpful include:
- Early use of pain relievers after trauma
- Use of sympathetic nerve block after trauma
- Desensitization techniques (if needed)
- Use of vitamin C —In a study, this was shown to reduce the risk of CRPS after a wrist fracture.
Diagnosis entails a thorough medical history and physical examination. Physical exams can be difficult to perform due to pain.