Complex Regional Pain Syndrome

There are two main types of CRPS:

• Type I CRPS: also known in the past as “reflex sympathetic dystrophy,” it occurs without identifiable nerve damage. It is the most common form, accounting for about 90% of cases.
• Type II CRPS: formerly known as “causalgia,” it is a rarer form that follows clearly identified nerve damage.

In addition to these two clinical types, there are also distinct progressive forms. We often refer to hot CRPS, in its initial phase with marked inflammatory signs, and cold CRPS, corresponding to older forms, when the disease becomes chronic. It should be noted that, unlike other types of pain associated with damaged nerves, CRPS pain does not follow a specific nerve pathway.

The symptoms of CRPS vary considerably from one patient to another, both in nature and intensity. Nevertheless, certain signs are recurrent and enable a diagnosis to be made, in particular thanks to the Budapest criteria, which are now internationally recognized.

The typical clinical picture includes:

• Persistent pain of severe intensity, described as a burning, crushing, electric shock, or vice-like sensation. This pain is disproportionate to the triggering event.
• Hypersensitivity to touch or cold, manifested as allodynia (pain caused by a normally painless stimulus) or hyperalgesia (exaggerated painful response to a normally painful stimulus).
• Skin changes such as color changes (red, bluish, or pale), local temperature changes, excessive or insufficient sweating, and edema.
• Motor disorders including joint stiffness, muscle weakness, tremors, or dystonia (involuntary contractions), which may restrict the use of the affected limb.
• Trophic signs such as changes in nail or hair growth, thinner or shinier skin.

It should be noted that the clinical picture evolves over time: the initial inflammatory symptoms may give way to tissue atrophy, cold discoloration of the limb, or irreversible functional limitation if treatment is delayed.

The exact origin of CRPS remains partially unclear, although several pathophysiological mechanisms have been identified. This syndrome most often appears following physical trauma (fracture, sprain, surgery, soft tissue injury). In these contexts, CRPS seems to result from an exaggerated response of the nervous system to tissue damage, a reaction that goes beyond the usual framework of pain and healing. Several mechanisms are likely involved:

• Exaggerated inflammation in the affected area, causing redness, swelling, and pain.
• An excessive reaction of the nerves, which send continuous pain signals even in the absence of significant stimulation.
• A malfunction in the brain in the way it processes sensations and movements, which maintains pain and functional impairment.

In some cases, no clear triggering event is identified. This reinforces the hypothesis of a combination of biological, nervous, and immune factors specific to each individual.

Some people seem more likely to develop CRPS after a triggering event, although the direct causal link is still being studied. Identified risk factors include:

It should be noted that there is no single typical profile, and that CRPS can affect anyone, including children, although this is rare.

The diagnosis of CRPS is based on a set of clinical signs and symptoms grouped into specific criteria. Since 2012, the international reference has been the Budapest criteria, established by the International Association for the Study of Pain (IASP). The diagnosis is therefore based on a thorough clinical evaluation by an experienced physician, sometimes supplemented by additional tests to rule out other causes, as no single biological or imaging test can confirm the diagnosis on its own.

The management of CRPS is based on a multidisciplinary approach, focused on functional recovery of the affected limb, pain relief, and improvement of quality of life. There is no single treatment or cure; effectiveness depends on a personalized combination of early interventions.

These treatments are chosen on a case-by-case basis, depending on the intensity of the pain, the patient's tolerance, and the progression of symptoms.

In refractory cases, some specialized teams may offer nerve blocks or neuromodulation techniques (spinal cord stimulation), although their use remains limited to selected cases.

Finally, psychological support and psychoeducation play an essential role in helping patients understand the disease, manage chronic pain, and avoid social isolation or depression.

CRPS is a condition that often has a long course, marked by significant individual variability. Some patients experience significant improvement or even remission, while others continue to experience residual pain and significant functional limitations several years after the onset of symptoms.

Recent studies show that: approximately three out of four patients experience a noticeable improvement within a year of the onset of symptoms, especially if treatment is started quickly.

However, when the disease is not treated early or is resistant to treatment, it can lead to complications:

• A decrease in strength and mobility in the affected limb, which can sometimes be permanent;
• Muscle atrophy, i.e., muscle wasting due to lack of movement;
• Joint stiffness and permanent stiffness (hand or foot remains bent);
• Chronic pain that sets in and becomes difficult to relieve;
• An impact on daily, professional, and social life;
• Body perception disorders, such as the feeling that the limb is no longer part of the body, or that it is deformed

These factors justify early and structured care to avoid the risk of chronicity and limit functional sequelae.

The prevention of CRPS is based primarily on measures taken as soon as trauma or surgery occurs, particularly in the limbs. The aim is to reduce inflammation, avoid prolonged immobilization, and promote a rapid return to mobility.

Recommended measures include:

• Encouraging early gentle mobilization of the injured limb, as soon as medically possible, to prevent contractures and maintain function.
• Informing at-risk patients (particularly those with fractures or who have undergone orthopedic surgery) about the early signs of CRPS, so that treatment can be started quickly if there is any doubt.
• Reducing preventable comorbidities, such as smoking or poorly controlled diabetes, which hinder recovery.
• In certain situations, particularly after a wrist fracture, studies suggest that taking vitamin C may slightly reduce the risk of developing CRPS, although the evidence remains limited and controversial. This preventive treatment should be discussed with a healthcare professional.

Prevention therefore relies on careful monitoring of at-risk patients and close collaboration between surgeons, primary care physicians, physical therapists, and pain specialists.

It is essential to consult a healthcare professional as soon as intense, persistent, and unusual pain occurs in a limb, particularly if this pain occurs after trauma, surgery, or immobilization.

Certain signs should raise alarm, in particular:

• Continuous pain that is disproportionate to the initial injury;
• Swelling, excessive local heat, or, conversely, cooling of the limb;
• Changes in the skin, hair, or nails;
• Loss of mobility or a feeling of abnormal stiffness;
• The appearance of burning sensations, tingling, or hypersensitivity to touch or cold.

Early detection can prevent chronic complications and maximize the chances of recovery. Any delay in diagnosis increases the risk of unfavorable progression of CRPS.

At Hôpital de La Tour, CRPS is treated using an interdisciplinary, patient-centered approach, in line with the latest standards in pain medicine.

The Pain Clinic recommends that patients be referred to us quickly, as soon as the diagnostic criteria are suspected to be met, or even when there is doubt. Rapid assessment and early intervention are essential, because the earlier action is taken, the lower the risk of chronicity.

Is CRPS a common disease?

CRPS remains a rare condition. Estimates vary between studies, but the annual incidence is between 5 and 26 cases per 100,000 people, with a predominance in middle-aged women.

Can CRPS be completely cured?

Yes, complete remission is possible, especially if treatment is started quickly. Approximately three-quarters of patients recover within a year of the onset of symptoms.

Can CRPS return after recovery?

Cases of recurrence have been reported, but they remain rare. CRPS can also spread to other parts of the body, sometimes even to the opposite limb, a phenomenon known as “mirror pain.”

Is CRPS a psychological disorder?

No. CRPS is a neuroinflammatory and neuropathic condition. However, psychological factors can influence its progression, as with other chronic diseases. Treatment that includes psychological support is often beneficial.

Is there a test to diagnose CRPS?

No. The diagnosis is clinical, based on the Budapest criteria, and confirmed after ruling out other causes. Imaging tests (MRI, scintigraphy) can be useful in ruling out other conditions, but cannot confirm CRPS on their own.

What are the first signs of CRPS?

Disproportionate pain, often described as burning or crushing, is the first typical sign. It may be accompanied by local heat, swelling, skin changes, and extreme sensitivity to touch or cold.