What Is Complex Regional Pain Syndrome?Complex regional pain syndrome is characterized as chronic pain, most often occurring in an extremity, which may be a result of dysfunction in the central or peripheral nervous system. This dysfunction may be related to a prior injury. Other symptoms of complex regional pain syndrome include problems with normal motor or sensory functions. Patients with this condition may experience pain disproportional to the original injury or tissue damage (if present). The symptoms of complex regional pain syndrome are usually perceived as being within one specific area of the body, but may radiate outward over time.
These symptoms may include:
- Skin discoloration
- Consistent pain that lasts for three months or more, often felt as a “throbbing” or “burning” sensation
- Increased sensitivity to cold or pressure
- Swelling in the affected area(s)
- Rapid changes from feeling cold to feeling hot or sweaty
- Altered hair or nail growth
- Increased joint immobility or inflexibility
- Muscular spasms
- Muscular atrophy (i.e. loss of muscular tone or strength)
- Impaired mobility in the affected body part(s)
Swelling, which may be accompanied by pain, and other symptoms that affect the skin (such as increased sensitivity to cold) are often seen at the onset of complex regional pain syndrome. Some research indicates that emotional stress may lead to increased symptom severity. This condition may lead to irreparable damage over time. Symptoms including muscle tightness or spasming, decreases in skin pigmentation, and reduced skin temperature may indicate that the condition is particularly advanced and possibly irreversible.
The exact cause of complex regional pain syndrome is not completely understood, but it is thought to be related to nerve damage in many cases. This is supported by observations that the inhibition of certain nerves associated with pain signaling results in improvements for patients with this condition.
Cause Of Complex Regional Pain SyndromeAs mentioned above, complex regional pain syndrome is currently thought to be linked to damage to nervous tissue. This damage may be a result of adverse events that result in severe injury. It may also be a result of myocardial infarction, stroke, or unintentional nerve injuries arising from surgery. These may all be associated with subsequent injury and inflammation of nervous tissue. This is thought to result in the perception of excessive pain that is disproportional to that expected to be normally associated with these conditions.
Complex regional pain may be linked to both the central and the peripheral nervous systems. Damage or dysfunction to small nerve fibers of the peripheral nervous system that interact with blood vessels may lead to inflammation. This may damage the nervous tissue, and also affect the blood vessel in question. This results in reactions such as constriction or dilation of the vessels. This may explain certain symptoms such as skin discoloration, changes in skin temperature, or swelling. In addition, the muscles served by these blood vessels may become deprived of oxygen as a result, manifesting in symptoms such as muscle weakness or joint stiffness.
Many cases of complex regional pain syndrome may be covered by this theory, i.e. being related to a specific injury or illness such as those outlined above.
Injuries that may cause the condition include:
- Limb fractures
- Blunt-force trauma, such as that incurred in the course of a motor vehicle collision
- Joint injury (e.g. ankle sprain)
- Infection that may be associated with subsequent tissue damage
- Soft tissue injury (e.g. lacerations or bruises)
- Complications arising from a surgical or medical procedure
Idiopathic cases of complex regional pain syndrome are relatively rare. These cases are thought to be related to a heretofore undetected condition, such as a nervous system or vascular tissue condition or infection. Few studies link complex regional pain syndrome to any genetic factors. Complex regional pain syndrome is not thought to be hereditary, or passed on from a parent to a child and so on.
Treatments For Complex Regional Pain SyndromePhysical therapy is thought to be beneficial for patients with early-onset complex regional pain syndrome. This treatment may address problems with mobility, blood flow, muscle strength, muscle tone, and joint stiffness. Many patients for whom physical therapy is effective in the early stages of illness may find that it reduces the chances of their condition becoming worse or more advanced.
No one single medication can address all the symptoms of complex regional pain syndrome, unfortunately. However, some can address one or two symptoms very well, and can be taken in accordance with those occurring in each individual case. Non-steroidal anti-inflammatory drugs (NSAIDs) may relieve mild to moderate pain and inflammation. Oral corticosteroids, such as prednisone and cortisone, also inhibit inflammation and may result in pain relief. Some other drugs such as anticonvulsants may effectively treat muscle tightness and stiffness, if present.
Spinal cord stimulation involves the surgical implantation of a device within the spinal column that disrupts pain signals as they travel to the brain. Intrathecal pump implants deliver painkilling drugs to spinal nerves in response to a remote control (also a feature of spinal cord stimulation) that the patient can operate personally at need. These are options for patients whose pain does not respond to conventional treatment (as above).
Alternative treatments for complex regional pain syndrome include biofeedback training. This treatment involves teaching a patient to read measurements such as electroencephalographs, and how they vary in response to pain or symptoms such as skin temperature changes. The patient then applies relaxation and coping techniques that can contribute to an alleviation of symptoms. Some patients find that acupuncture, in which sterile stainless-steel needles are placed into specific points in the body to promote endorphin release, is also effective in treating their symptoms.
Complex regional pain syndrome is thought to be the result of disproportional responses in the central and peripheral nervous system as a result of tissue damage. It is characterized as chronic pain, skin abnormalities, muscular atrophy, and other symptoms.
Treatments that may manage complex regional pain syndrome include some medications, biofeedback training, or spinal cord stimulation. A discussion with your pain specialist about the nature of your pain and other symptoms will result in the best possible treatment plan for you.
- Borchers AT, Gershwin ME. Complex regional pain syndrome: A comprehensive and critical review. Autoimmun Rev. 2013;13:[Epub ahead of print].
- Di Pietro F, McAuley JH, Parkitny L, Lotze M, Wand BM, Moseley GL, Stanton TR. Primary motor cortex function in complex regional pain syndrome: A systematic review and meta-analysis. J Pain. 2013;14(11):1270-88.
- Harden RN, Oaklander AL, Burton AW, Perez RS, Richardson K, Swan M, Barthel J, Costa B, Graciosa JR, Bruehl S; Reflex Sympathetic Dystrophy Syndrome Complex regional pain syndrome: practical diagnostic and treatment guidelines, 4th edition. Pain Med. 2013; 14(2):180-229.
- Hauser J, Hsu B, Nader ND. Inflammatory processes in complex regional pain syndrome. Immunol Invest. 2013;42(4):263-72.
- Pertoldi S, Di Benedetto P. Shoulder-hand syndrome after stroke: A complex regional pain syndrome. Eura Medicophys. 2005;41(4):283-92.
- Stanton TR, Wand BM, Carr DB, Birklein F, Wasner GL, O’Connell NE. Local anaesthetic sympathetic blockade for complex regional pain syndrome. Cochrane Database Syst. Rev. 2013;19(8):[Epub ahead of print].