Chronic Regional Pain Syndrome

What is Chronic Regional Pain Syndrome?

Chronic Regional Pain Syndrome, also referred to as Complex Regional Pain Syndrome, is a debilitating medical condition, unfortunately known for the severe, long-lasting pain that is usually localised to a limb. In spite of this simple Complex Regional Pain Syndrome definition, this medical condition is far from easy to understand. Nevertheless, through years of studying Chronic Regional Pain Syndrome, some insight has been gained with regards to the causes, symptoms, diagnosis, treatments, and prognosis of the disorder. These will all be highlighted and explained in due course within this article.

What causes Chronic Regional Pain Syndrome?

From the definition given above of Chronic Regional Pain Syndrome, it is clear that an individual affected by it will often be in unimaginable pain. But what exactly causes the pain that Chronic Regional Pain Syndrome is known for? To date, the exact cause is unknown. However, several events and conditions have been identified in relation to the onset of Chronic Regional Pain Syndrome in some patients. It should be noted that not every individual who goes through these events or under these conditions ends up with Chronic Regional Pain Syndrome. The explanation for that, whether scientific or logical, isn’t known. The following initiating noxious events and conditions are some of the causes that have been identified as leading to the development of Chronic Regional Pain Syndrome in some patients:

  • Injuries

Whether the injury is serious and intense like a broken limb, or less severe like a sprain; either of them may lead to Chronic Regional Pain Syndrome. A good indication of this would be if the individual finds the pain from their injury more severe than what would normally be expected and if the pain persists for a longer time than normal. 

  • Surgery

In some cases, a surgical operation may cause Chronic Regional Pain Syndrome. It might be that the body fails to heal properly following the surgery, or something minor goes wrong during the surgery itself. Some Complex Regional Pain Syndrome settlements may actually result from cases where a patient’s surgery was not handled well by medical practitioners. Not all patients who undergo surgery end up with Chronic Regional Pain Syndrome, but it is certainly one of many risks of any surgical operation.

  • Minor medical procedures

Though it may be hard to believe, something as inconsequential as needle stick may cause Chronic Regional Pain Syndrome. Again, the exact science behind why some people will end up with Chronic Regional Pain Syndrome while others don’t, even though they undergo the same procedure is anyone’s guess. It could be chalked up to simple human error during the procedure or the body’s biological makeup, or anything else.

  • Immobilisation

In the event of injuries such as sprains on the hand or something similar, an individual may have to wear a sling to keep them from moving the injured limb and hurting themselves more or delaying the healing process. Sometimes this may end up causing more harm than good, as prolonged immobilisation may cause Chronic Regional Pain Syndrome.

  • Daily occupational activities

Something as simple as typing for several hours a day on a daily basis may result in pinched nerves in the hand, which leads to Carpal Tunnel Syndrome, which in turn is one of the identified causes of Chronic Regional Pain Syndrome.

  • Pre-existing conditions

For some patients, pre-existing abnormalities in the peripheral nerves may cause Chronic Regional Pain Syndrome. An abnormality in these nerves may be something as simple as miscommunication between sensory nerve fibres and blood vessels which results in increased sensitivity to pain in the affected individual. Such hypersensitivity to pain is just one of the many symptoms of Chronic Regional Pain Syndrome.

  • Medical conditions

Strokes, heart attacks, and cancer are some of the medical conditions that may lead to the onset of Chronic Regional Pain Syndrome. The disease itself may be the causal effect, or it might be effects of the medical condition such as immobilisation from a stroke, or maybe even the treatments used for the diseases like radiation therapy in cancer patients.

Chronic Regional Pain Syndrome Types

Despite the many possible causes of Chronic Regional Pain Syndrome, some distinction among the many options has made it possible for two types of the medical condition to be identified. The first types is called Chronic/Complex Regional Pain Syndrome Type 1, while the second is Chronic/Complex Regional Pain Syndrome Type 2. For the most part, the two types are similar. The only difference between them is that Chronic Regional Pain Syndrome Type 1 occurs after an initiating noxious event, whereas Chronic Regional Pain Syndrome Type 2 develops in the presence of significant nerve damage.

Chronic Regional Pain Syndrome Type 1

This form of the medical condition is the most common in the majority of Chronic Regional Pain Syndrome patients. As mentioned before, an initiating noxious event such as a surgical procedure, fracture, sprain or any other injury is usually the leading factor in the onset of this type of the disorder. Chronic Regional Pain Syndrome Type 1 is also known as Reflex Sympathetic Dystrophy or RSD for short.

The International Statistical Classification of Diseases and Health Related Problems has several Chronic Regional Pain Syndrome ICD 10 classifications according to the limb which is affected. The medical classification list even goes on to classify each type separately so that Chronic Regional Pain Syndrome Type 1 has its own set of codes ranging from G90.50 to G90.59 for unspecified regions of the body, upper limbs, lower limbs, left and right limbs, as well as any other specified site.

Chronic Regional Pain Syndrome Type 2

This second type of the medical condition was formerly known as Causalgia which means “burning pain”—an accurate description of Chronic Regional Pain Syndrome as a whole. Chronic Regional Pain Syndrome Type 2 is rare and in spite of the difference between it and its counterpart, both are regarded in the same way when it comes to diagnosis and treatment. The Chronic Regional Pain Syndrome ICD 10 codes for the Type 2 condition range from G56.4 to G57.72, with variations in between to specify whether the upper, lower, right, left, or an unspecified limb is affected by Chronic Regional Pain Syndrome.

Chronic Regional Pain Syndrome Symptoms

The number one symptom that any Chronic Regional Pain Syndrome patient would report is likely to be pain. It is the most prominent out of all symptoms and even though not all symptoms present themselves at the same time, pain is usually the number one indicator of Chronic Regional Pain Syndrome in a patient. The severity of Chronic Regional Pain Syndrome pain is so bad that the disorder has a score of 42/50 on the McGill Pain Index—miles above the pain of childbirth and the amputation of a finger or a toe.

The other symptoms of Chronic Regional Pain Syndrome are:

  • Abnormal sweating

A patient may notice abnormal sweating on the affected region. This is due to vasomotor disturbances which affect vasoconstriction and vasodilation, which in turn results in abnormal sweating of the skin of the affected region. 

  • Skin temperature differences

Similar to abnormal sweating, the skin’s temperature is controlled by naturally occurring processes within the body such as vasoconstriction and vasodilation. When these processes stop functioning properly, this can cause the body’s temperature control to go haywire resulting in skin temperature variations, especially in the affected parts. 

  • Skin colour changes

The colour of the skin may change to a blotchy, blue, purple, pale or red appearance. These skin colour changes from Chronic Regional Pain Syndrome occur because of abnormal microcirculation which stems from damaged nerves.

  • Hyperalgesia

This is a heightened sensitivity to pain which results in Chronic Regional Pain Syndrome patients feeling pain that is disproportionate to the inciting injury or event.

  • Allodynia

Allodynia is increased sensitivity to normally non-painful stimuli. This means an individual with Chronic Regional Pain Syndrome may feel pain from something as ordinary as loud noises or light brushing of the skin.

  • Motor disorders

As a result of the severe pain that Chronic Regional Pain Syndrome patients feel, moving the affected limb may become difficult to the point that they completely stop using it. That kind of immobility, especially if it lasts for a long period of time may cause problems like paralysis, weakness, tremors, and limited range of motion.  

  • Oedema

Oedema is a medical term used for fluid retention in the body. It is actually this build-up of fluid that causes swelling in the body—another symptom of the disorder. In Chronic Regional Pain Syndrome patients, the swelling is usually localised to the affected region, although if the condition is left untreated, this may worsen and spread.

  • Abnormal hair or nail growth patterns

These abnormalities may possibly be a result of the loss of bone mineral which occurs with the progression of the medical condition. Calcium is vital for hair and nail growth, so the deficiency that mineral may affect those two.

These are some of the more common Chronic Regional Pain Syndrome symptoms. They may not manifest in a patient all at the same time. This makes it difficult to diagnose the medical condition, especially since the symptoms are the main factor that is evaluated to determine whether or not a patient has Chronic Regional Pain Syndrome. There is no single medical test that can definitively diagnose the medical condition, so a guideline called the Budapest Criteria is used. The Complex Regional Pain Syndrome Budapest Criteria diagnostic tool is used along with medical tests such as X-rays and Bone scans which help eliminate other possible diseases with similar symptoms.

Chronic Regional Pain Syndrome Stages

The symptoms mentioned above may present themselves in several stages over time. Three distinct stages of the disorder have been identified and these are as follows:

  • Acute

The first stage lasts almost 3 months. During this period, the patient feels severe pain along with other symptoms such as swelling, skin temperature variations, and mobility issues.

  • Subacute

This second stage can last for up to 9 months and in that time period, the patient’s symptoms may advance such that their pain increases to the point of them not wanting to move the limb at all. Extended immobility only serves to worsen motor disorders such that loss of function may increase. This is also the stage where the skin may begin to change and demineralisation of the bones in the affected area becomes more pronounced.

  • Chronic

The chronic stage may be the point of no return for some Chronic Regional Pain Syndrome patients. It begins from about a year after the initial onset of the medical condition and may continue for a number of years or become permanent. The pain may increase or subside and loss of function gets worse.

Chronic Regional Pain Syndrome Treatment

Just as the medical condition is difficult to understand, it is equally hard to treat. Regardless, a number of treatments have been found and used to offer relief from the symptoms. Chronic Regional Pain Syndrome treatment usually combines medications, physical therapy and psychotherapy for the best results. Early treatment is usually recommended for a better chance at recovery.


A combination of drugs may be required for the effective treatment of Chronic Regional Pain Syndrome. The medications prescribed and recommended usually target the prominent symptom of pain. These include analgesics, anticonvulsants, antidepressants, opioids, calcium channel blockers, and anaesthetics among many others. The degree of efficacy for any of these will vary for each patient. Some patients may need to use all these together or just a few of them for pain relief. Others may even opt for Complex Regional Pain Syndrome nerve blocks, although these don’t work for everyone.

One drug currently making waves in the world of Chronic Regional Pain Syndrome treatment is Neridronate—a bisphosphonate that is believed to offer long-lasting relief from the symptoms. So far, Neridronate has only been approved for use in the treatment of Chronic Regional Pain Syndrome in Italy so anyone looking to try it out would need to go there for treatment. The level of pain relief from Neridronate varies with each patient, such that some may actually get total remission while others may only feel slight relief. It is believed that the chances for full recovery with Neridronate are higher in the early stages of Chronic Regional Pain Syndrome.


Loss of limb function is another symptom of Chronic Regional Pain Syndrome, which also happens to be an effect of the major symptom of pain. Functional restoration is vital for the recovery of a patient and physiotherapy helps with that. This may involve simple exercises to help the patient get used to moving the limb more and improve their pain threshold, as well as mental exercises such as Mirror Visual Feedback and Graded Motor Imagery that change the patient’s perception of their pain. In the long run, this helps the patient manage their pain and lessen their dependency.


The mind of a Chronic Regional Pain Syndrome patient is likely to get affected as a result of the patient having to deal with constant pain on an almost daily basis. Their dependency on caregivers for simple, daily tasks may also contribute to the detriment of their mental state such that they often feel depressed, anxious, and stressed. This emotional turmoil can actually worsen their condition as it may lead to flare ups where the patient experiences periods of enhanced pain. Psychotherapy is therefore recommended to help the patient get a handle on their emotional state and prevent flare ups and psychological damage.

Chronic Regional Pain Syndrome Prognosis

Children have a better chance at a fast recovery, as compared to adults with Chronic Regional Pain Syndrome. There is no way to tell how any individual’s case will pan out but early diagnosis and immediate treatment offer the best chances at a recovery.