Oldies but Goodies – What is Complex Regional Pain Syndrome – in plain English

Over this holiday season we are posting the most read articles from the last five years.  Here is the first.

What is Complex Regional Pain Syndrome – in plain English

What is Complex Regional Pain Syndrome? Well, complex regional pain syndrome (CRPS) is exactly that

Complex: Many, many different problems have been identified in people with CRPS. These problems can be severe and usually involve many of our biological systems.  This makes the situation complex.

Regional: The symptoms of CRPS are almost always confined to a particular region of the body. The arm of the leg is the most commonly involved region. Sometimes CRPS of one arm spreads to the leg on the same side of the body. Sometimes it spreads to the opposite arm, in which it usually ‘mirrors’ the other one.

Pain: CRPS is exquisitely, severely, painful. Like the other symptoms, the pain is confined to the affected limb or limbs.  Often the skin is too tender to touch and the whole limb is too painful to move. In fact, sometimes the limb is too painful to even imagine moving [1,2].

Syndrome: A syndrome is a pattern of symptoms that often occur together.  Normally, the reason that something is called a syndrome is that we do not know what causes it, we just know that this pattern of symptoms occurs together and usually at the same time.

So, CRPS is the name given to a pattern of symptoms that often occur together.

Diagnosis of CRPS

Because CRPS is not based on a particular injury, bacteria, virus, or other identifiable cause, diagnosis of CRPS relies on the symptoms and signs (what’s the difference between signs and symptoms? – see Note 1 at the end of the article) Not all the signs and symptoms are always present. So, the official position established and endorsed by the International Association for the Study of Pain is that we should use this checklist:

Symptoms and Signs of CRPS

Symptoms and Signs of CRPS

These are the symptoms (the things the person feels) 
Continuing pain that is disproportionate to the inciting eventy/n
The skin is painful to touch - this is called allodynia
The skin feels very sensitive - this is called hyperaesthesia
The limb feels colder or hotter than the other one (presuming that the other one is not affected)
The limb changes colour for example, it goes blue, or red, or white, or mottly
The limb feels swollen
The limb seems to sweat more than the other one
The limb doesn’t move properly
The limb shakes
The limb is very weak

The finger or toe nails grow faster than those on the other hand or foot
The hair on that limb grows faster than the hair on the other limb

These are the signs (the things someone else assesses) 
Increased pain caused by a pin prick (hyperalgesia)
Pain caused by gentle stroking of the skin (allodynia)
The limb looks to be a different colour from the other one
The limb is colder or warmer than the other one
There is current oedema, or clear evidence of past oedema
The limb is more sweaty than the other one
There is reduced range of motion
There is tremor (the limb shakes when the patient tries to move it)
There is fixed dystonia (the limb is stuck in an awkward posture)
The fingernails or toenails on the affected limb are different to those on the other one
The hair on the affected limb is longer or darker than the hair on the other one


To be diagnosed with CRPS, the following criteria have to be met:

  1. The compulsory item is ticked
  2. At least one symptom in each group of symptoms is ticked.
  3. At least one sign in 2 or more of the groups of signs is ticked.

So, this means that you can not really diagnose yourself with CRPS based simply on your symptoms.  There is no added diagnostic value of: x-rays, bone scans, blood tests, sympathic function tests, quantitative sensory testing, nerve conduction tests.

How many people have CRPS?

No one really knows how many people have CRPS, but some really good research studies give us a rough idea.  For example, one really good study, undertaken in The Netherlands [3] suggests that, every year, one person in every 4000 will develop CRPS.  That doesn’t really sound like many, but it means that about 5000 Australians, 20 000 Brits and 75 000 Americans, will get diagnosed with CRPS this year.  That is how many people will get it.  How many people will actually have it in any given year? In crude terms, you can just multiply that number by 5 – 25 000 Australians, 100 000 Brits and 400 000 Americans.  Now the numbers look big. They look even bigger when you consider that treatment for each patient with chronic CRPS costs about AU$12,000 per year and total lost income due to CRPS in Australia (a small country by population standards) exceeds $1 billion [4].   So, if you are someone with CRPS, you are not, by any means, alone. If you are someone trying to decide whether to fund CRPS research, you surely should!

What causes CRPS?

We don’t know this either.  One theory suggests that something goes wrong with the inflammatory response after a minor injury so that it just winds up and up until the whole protective system is very very sensitive.  Another theory is that CRPS results from psychological weakness and another that it relates to certain personality types.  The last two theories have been proven wrong – in the largest study, these things were not related to having CRPS: pre-injury psychological profile (including ‘personality’), biomechanical factors (the specific size, shape, configuration and movement of your body parts), injury characteristics (how and what you injured), surgical approaches (what operation, if any, they did), compensation and previous illness history [3].  The first theory has neither been proven wrong, nor proven right. Both seem possible.  It is also possible that there are several potential causes of CRPS. We really don’t know.

What we do know is that the response to tissue trauma (injury) is excessive.  We know that the autonomic nervous system (the system that controls blood flow to your body) is involved, most probably by altered sensitivity to adrenaline.   We know that the immune system is involved. We know that the system that controls movement is involved.  Last, but not least, we know that the pain system is involved.

Acute CRPS seems different to chronic CRPS

In acute CRPS, temperature changes almost always involve the limb being hotter than normal and hotter than the other one, and being redder than normal.  As CRPS progresses, a cold and white limb becomes more common and people often notice that the hair or nails, or both, on that limb, are growing faster than normal and faster than the other limb.  Chronic CRPS is also associated with other evidence of dysfunction within the central nervous system, including the brain.  For example, there is some evidence that people with chronic CRPS think that their affected limb is bigger than it really is; they often feel as though the limb doesn’t belong to them anymore; the sensory system can develop errors so that one can’t be sure exactly where on the limb one has been touched unless they are looking at it; it can become more and more difficult to move, develop the shakes, or become ‘stuck’.  These are all things that are distressing but they are also things that we think can be treated with appropriate rehabilitative treatments – although the evidence is weak because it is a very recent direction in treatment.

What is the best treatment for CRPS?

In order to determine if a treatment is effective, it must be tested with the strongest experiments possible.  Although many treatments have been used for CRPS, only a small few have been tested with strong experiments.  We can categorise treatments according to the results of experiments (See Table in Note 2):

Treatments for acute CRPS

  1. Anti-inflammatory therapies: Some are good, some a probably no good and some are definitely no good.
  2. Analgesics: Some might be good (eg ketamine intravenously or gabapentin) but there are no good experiments on it; some are no good (eg local anaesthetics, anti-epileptics, serotonin reuptake inhibitors).
  3. Spinal cord stimulators are probably good, although remember that there are risks with inserting a stimulator onto your spinal cord and many need revision or relocation.
  4. TENS is no good.
  5. Activation & mobilisation (eg physical therapies) are probably good as long as they promote movement and function, not targeting pain relief.
  6. Mirror therapy is probably good.

Treatments for chronic CRPS

  1. Spinal cord stimulators are probably good although remember that there are risks with inserting a stimulator onto your spinal cord and many need revision or relocation.
  2. Graded motor imagery is good (and also see graded motor imagery for pathologic pain)
  3. Tactile discrimination training might be good but there are no good experiments on it (see also our other paper on tactile discrimination).
  4. The other things that are listed for acute CRPS are not effective for chronic CRPS.

Where can I tell my doctor or physiotherapist to look for more information on treatment guidelines?

There are official guidelines developed in The Netherlands. The guidelines are a little out of date but the best around (http://pdver.atcomputing.nl).  The RSDSA association has a bundle of resources for clinicians and patients. BodyInMind has resources for clinicians, including teaching materials and publications.

What research is being done?

The most impressive concerted research effort involving CRPS is going on in the Netherlands. It is called TREND and you can have a look here. Also, the National Institute of Neurological Disorders and Stroke (NINDS) and other institutes of the National Institutes of Health (NIH) conduct research relating to CRPS in laboratories at the NIH and also support additional research through grants to major medical institutions across the country. NINDS-supported scientists are studying new approaches to treat CRPS and intervene more aggressively after traumatic injury to lower the chances of developing the disorder.  The Australian National Health & Medical Research Council funds clinical studies into CRPS after wrist fracture.


1. Signs and Symptoms

Signs are things that someone else can observe. Symptoms are things that you feel. For example, feeling cold is a symptom.  Actually being cold is a sign.

2. Evidence that something works

CategoryWhat it means
Level 1-2 evidence of efficacyStrong experiments show that the treatment is good
Level 3 evidence of efficacyNot very strong experiments suggest the treatment might be good, but we need strong experiments to really know
Level 4 evidence Some experts think the treatment is good but there are no experiments, so we really don’t know
No evidenceNo one really knows

Evidence that something doesn’t work

CategoryWhat it means
Level 1 - 2 evidence of no effectStrong experiments show that the treatment is not better than a placebo
Level 3 - 4 evidence of no effectNot so strong experiments suggest the treatment is no better than a placebo,which means it is almost certainly no better than placebo
Level 1-4 evidence of harmStrong experiments, weak experiments or expert opinion suggest the treatment is harmful


  1. Moseley, G.L. (2004). Imagined movements cause pain and swelling in a patient with complex regional pain syndrome. Neurology 62, 1644.
  2. Moseley, G.L., Zalucki, N., Birklein, F., Marinus, J., Hilten, J.J.v., and Luomajoki, H. (2008). Thinking about movement hurts: The effect of motor imagery on pain and swelling in people with chronic arm pain. Arthritis Care & Research 59, 623-631.
  3. de Mos, M., de Bruijn, A.G.J., Huygen, F.J.P.M., Dieleman, J.P., Stricker, B.H.C., and Sturkenboom, M.C.J.M. (2007). The incidence of complex regional pain syndrome: A population-based study. Pain 129, 12-20.
  4. Kemler, M.A., and Furnee, C.A. (2002). The Impact of Chronic Pain on Life in the Household. Journal of Pain and Symptom Management 23, 433-441.

Lorimer Moseley (2009). What is Complex Regional Pain Syndrome – in plain English BodyInMind


  1. I developed CRPS after a hand injury several years ago. It eventually spread full body & I was incapacitated. All conventional treatments failed. My CRPS was put into complete remission when I had bilateral ECT for the depression the pain had brought on. I am now pain free and healthy. ECT is a radical treatment but it reversed my CRPS completely and had very few side effects. There are many case studies where ECT has alleviated CRPS so I think pain management experts need to be directing research into the areas of ECT or transcranial stimulation. Regular pain medications are not effective.
    Best of luck to everyone out there dealing with CRPS.

  2. Kevin Scardifield says:

    Will you help Raise awareness of CRPS?
    2017 is 525600 minutes long; in a split second from a twisted ankle or an injection you could become one of us so please spare 6 mins to watch the whole of this video. I remade it 9 times and the band practiced for hours to make it the best we could. https://www.youtube.com/watch?v=-eoQPgYI3l4
    If you can spare 99p then please buy the song.
    If you can spare another 520 mins throughout the year and want to help CRPS sufferers across the world then Join the CRPS Global Awareness Campaign https://www.facebook.com/groups/1792800220936741/ and send this message to anyone and everyone you can asking them to do the same.
    Thank You

  3. Julie macpherson says:

    My right leg mainly foot and right hand swell to extreem my scalp hurts a great deal just to touch mainly in centre . My right foot has discoloration . In constant pain on my roght side. Both arms hurt and a simple touch anywhere on my body hurts. I have trouble with constant blurred vision even with my new reading glasses to the piont wherevi cant see and it is very painful. I also have fibromyalgia, osteoporosis and osteoarthritis, poly arthritis. Had rheumatic fever as a child and could not walk. Have neuralgia, multiple spinal fractures and several crushed discs.

  4. May I reach to the pdf form of this article ?

    BiM Reply:

    Hi Sezai. Any journal articles we have available can be found here: http://www.bodyinmind.org/resources/journal-articles/. Hope this helps

  5. Annette Merkley says:

    I’m still hoping a cure will be found for this horrible condition…in my lifetime…for my daughter’s sake! …and I’m curious to know if other countries are making it almost impossible for folks with this disease to get the opioids they need to function…our USA has made laws restricting the use of these needed drugs supposedly to prevent opioid addiction…causing more stress for people with CRPS and other pain conditions.