What is CRPS, and what is it not?
CRPS is a pain condition that arises after an injury or operation on the arm or leg. The pain exceeds what the original damage explains, and it persists although the bone has long since healed. Usually the whole hand is affected, not the area supplied by a single nerve.
The name has changed, the illness has not. The surgeon Paul Sudeck described the picture around 1900, and for decades it was called Morbus Sudeck, Sudeck’s dystrophy. Today it is called complex regional pain syndrome, CRPS for short: “complex”, because several systems lose their footing at once, from pain processing to circulation; “regional”, because a section of the body is affected and not a single nerve.
What CRPS is not
- Not imagined pain. The international classification of diseases lists CRPS as a pain syndrome in its own right, and the changes in skin, circulation and movement are measurable.
- Not proof that you did something wrong. CRPS also arises after fractures treated by the book.
- Not a question of willpower. Fear worsens the course, and that is proven. It is not the trigger.
- Not an infection, not a thrombosis, not rheumatism. All three look similar at first and have to be ruled out.
In type I no injury to a larger nerve is found; that is the more common form after a fracture. In type II nerve damage has been demonstrated.
After which events does CRPS occur?
At the start there is almost always an event in the limb. Fractures make up around 40 to 50 per cent of all cases, above all the radius fracture at the wrist. After an operation on arm or leg a small share of those operated on develop CRPS, varying with the procedure. Small events are enough too.
The most common route into CRPS in the hand runs through a fracture of the radius just before the wrist; two to five in a hundred people then develop CRPS. What is normal is set out in the article on the wrist fracture: a swollen, stiff hand after the cast comes off is the rule. Pain that grows from week to week is not.
- Bone fractures, especially at wrist and ankle and those that reach into the joint.
- Operations on arm or leg, including small and technically faultless ones. What to expect after an operation is set out in hand therapy after surgery.
- Nerve injuries, which CRPS can also follow.
- Minor events such as a sprain or an injection. Sometimes no clear event is found at all.
The risk rises with extensive tissue damage, long immobilisation, high pain intensity from the outset and marked anxiety. Women are affected two to four times as often, the peak age lies between 40 and 60, and 5 to 26 in 100,000 people develop it each year.
How do I recognise CRPS in the hand?
The leading sign is pain that does not match its trigger and grows over time instead of easing. Alongside it come swelling, a difference in skin colour and temperature compared with the other hand, changed sweating, very sensitive skin, and movement that gets worse week by week.
- Pain that does not fit. Stronger than the fracture warrants, at rest and at night too.
- Swelling. The hand stays thick despite being raised, and rings no longer come off.
- Colour and temperature. Markedly warmer and red, or colder and bluish, than the other hand, and often changing.
- Sweating. The affected hand sweats more or less than the healthy one.
- Sensitivity to touch. Even the sleeve or the bed sheet hurts. The technical term for this is allodynia.
- Movement. The fingers close less well rather than better; sometimes tremor and changed nail growth come with it.
The pattern says as much as the signs themselves. A trapped nerve causes symptoms only in the area it supplies; CRPS takes in the whole hand, as if bounded by a glove.
This picture is carried by the activity of the nerves themselves. The nerve fibres that report pain, temperature and touch are excitable beyond the normal degree, and the spinal cord and the brain amplify the incoming signals on top of that. So a touch that would earlier have set off nothing now hurts, and so the therapeutic approach has to be a careful one: every stimulus is dosed so that the system can still place it, rather than amplify it again.
Around 70 in a hundred people have a warm, reddened CRPS, and the other 30 a hand that is cold and bluish from the start. The cold form counts as the more stubborn one.
How is CRPS established?
Your doctor makes the diagnosis, and it is made on the person, not on the image. The basis is the Budapest criteria: you report symptoms from at least three of four groups, the examination finds signs from at least two, and no other condition explains the picture better.
- There is persisting pain that the original event no longer explains.
- You report symptoms from at least three of the four groups named below.
- The examination finds signs from at least two groups. Reported is not enough here; it has to be visible or palpable.
- There is no other condition that explains the symptoms better.
- Sensation: raised sensitivity to pain, pain on touch that would otherwise be harmless.
- Circulation: skin temperature and skin colour different from the other side.
- Sweating and swelling: unequal sweating between the sides, swelling.
- Movement and tissue: restricted movement, tremor, deformity, loss of strength, changed hair and nail growth.
Imaging does not prove CRPS. Only about half show patchy decalcification near the joints on X-ray after four to eight weeks; magnetic resonance imaging is not suited to making the diagnosis. Investigation serves above all to rule out other causes.
The criteria are set generously: they capture almost everyone affected, but they also come out positive in people without CRPS. So the timing counts; the German-language treatment guideline on CRPS that this text draws on provides for the diagnosis in the first months after the event. A CRPS that only appears as an explanation years after an accident is hard to establish with these criteria.
Why does recognising it early make such a difference?
Because two things happen at once in the first weeks: the nervous system learns the pain, and the hand loses movement that is hard to get back later. The earlier active treatment starts, the better the course; this is where you and your doctor really can change something.
One warning sign has been well studied: anyone still reporting pain of five or more on a scale up to ten a week after a radius fracture is at raised risk. That is not proof, but it is a reason to telephone.
Early assessment counts for a second reason. Many people hear for months that the X-ray looks fine, and it is only the diagnosis, once made, that places their symptoms as a described illness.
What helps in CRPS?
What is proven is active treatment. Moving within the low-pain range, desensitising the oversensitive skin several times a day, mirror therapy, and a step-by-step return to movements that have been avoided. Alongside that, pain medication prescribed and monitored by a doctor. Passive measures that go past the pain limit count as harmful.
- Moving within the low-pain range. Never past the limit beyond which the pain echoes for hours. In the studies it was two to five therapy sessions a week.
- Desensitising. The oversensitive skin is touched several times a day with different materials, from easily bearable to less bearable.
- Mirror therapy. The healthy hand moves in front of a mirror that hides the affected one; the brain sees a pain-free movement. For early cases there is evidence for this.
- Graded motor imagery. A staged programme of left-right recognition, imagined movement and mirror therapy. Two controlled studies found an effect; a later observational study without a control group could not confirm it.
- A step-by-step return to what you avoid. The aim is the task itself, such as being able to close a zip again.
- Measures against the swelling, and assistive devices for everyday life.
Your doctor decides about medication. In early CRPS with redness, warmth and swelling, cortisone is an option in the short term; whether it takes hold shows within a few days and at most three weeks. For bisphosphonates several controlled studies exist; for much of what is recommended on the internet, evidence is lacking.
On occupational therapy itself the evidence is thinner than its spread suggests: the effect in the available studies came out smaller than that of physiotherapy, and the studies are small. What is proven is the direction: active rather than passive, and under your control. In hand therapy you therefore set the pace. Because fear measurably worsens the course, psychological support is part of it for many people, and as part of the pain treatment.
Why do immobilising and gritting your teeth both do harm?
Immobilising takes pain away in the short term and costs movement in the long term: joints stiffen, and the brain stops passing the commands for feeling and moving properly to the hand. Gritting your teeth produces peaks of pain that wind the oversensitive system up further. Both worsen the course; the right dose lies between them.
Long immobilisation is described as a risk factor, both for CRPS arising and for its course. What is not moved shortens, joint capsules and ligaments among them. At the end stand deformities of the fingers that remain, even once the pain eases. A hand that is kept out of every task for weeks also feels foreign and obeys less well.
The opposite advice is just as widespread and just as wrong. The guideline is clear: passive measures applied without your control, which increase the pain, are not indicated in CRPS.
What happens next, and how long does it take?
In the individual case that cannot be predicted. The guideline states that in most cases you have to reckon with burdensome pain over about a year, often longer. Without complicating circumstances the symptoms largely recede in around half of those affected. A residual sensitivity often remains.
Anyone who promises you a cure within a set number of weeks is going beyond the data. The aims in the guideline are these: to get the pain under control and to win back function to a large extent. Being able to take less afterwards is common and is not a failure of the treatment.
Something can be said about the direction. Favourable are an early diagnosis, an early start to treatment and a warm picture at the beginning. Unfavourable are a hand that is cold from the outset, painful procedures, invasive interventions without clear grounds, and marked anxiety. Children have better prospects than adults.
On the practical route in Switzerland: occupational therapy is prescribed by a doctor, after an accident usually through accident insurance and otherwise through the insurer responsible. Pain treatment and the build-up of load have to be tuned to each other. With a prescription you can arrange an appointment with us.