Complex regional pain syndrome (CRPS) is a poorly understood condition in which a person develops a persistent (chronic) burning pain in one of their limbs.
The pain usually develops after an injury - which in most cases is a minor injury - but the pain experienced is out of all proportion to what you would normally expect. For example, a person with CRPS may only strain their ankle but it can feel like a serious burn.
The skin of the affected body part can become very sensitive, and even the slightest touch, bump, or change in temperature can provoke a feeling of intense pain.
If left untreated the pain can spread to other parts of the body too.
Read more information about the symptoms of complex regional pain syndrome.
In some cases of CRPS the pain passes after a few weeks. In others it can persist for months or even years. Some people have repeated episodes of pain followed by long stretches of remission (being pain-free).
There are three main treatment approaches for CRPS which are used in combination:
The sooner treatment is started after symptoms begin, the more effective it will be.
Read more information about the treatment of complex regional pain syndrome.
What causes CRPS
The cause of CRPS is unknown but the condition appears linked to an abnormal neural (involving the nervous system) response to injury.
It appears something (nobody is sure what) causes certain nerves to misfire in some way triggering pain.
CRPS could be the result of interconnected factors.
A previous theory that CRPS was a psychosomatic condition (the symptoms of pain were psychological - "all in the mind") has been disproved because research shows people with CRPS undergo very real physical changes in their nervous system.
Read more about the possible causes of complex regional pain syndrome.
Who is affected
It is hard to estimate exactly how common CRPS is as many cases may go undiagnosed or misdiagnosed. One study reported as many as 1 in 3,800 people in England may be affected by CRPS.
CRPS can begin at any age, though the average age for symptoms to start is around 40. Three out of four cases occur in women.