Chronic regional pain syndrome or CRPS is a condition which may develop in the hands and arms, feet and legs. It consists of persistent severe burning pain, swelling, loss of the ability to use the muscles and in some cases, discolouration of the skin. This can gradually spread up the arm or leg. In fact CRPS affects so many different systems that it is known as a multi-system disorder.
What are the symptoms of CRPS?
Patients with CRPS can have many different symptoms. For example, the limb may be hot or cold; swollen and shiny or thin; red or blue. The skin may be scaly or clammy. Bones may or may not have localised osteoporosis. Some patients cannot tolerate even slight air movement on their skin, while others have completely lost the ability to feel even the lightest touch on the limb. Joints are usually stiff and weak: often parts of the limb cannot be moved at all.
What causes CRPS?
Recent studies have found that CRPS is more common than previously thought and that women outnumber men by 3.5 : 1. The age group most affected is 55–75 years, but when it affects younger people, CRPS tends to be more serious. In more than 90% of cases, CRPS is triggered by an injury or trauma. The most common triggers are fractures, sprains and strains, soft tissue injuries (such as burns, cuts, or bruises), limb immobilization (such as being in a cast), and surgical or medical procedures. It may develop in the hands following carpal tunnel syndrome or an injury such as a wrist fracture. The most important feature is that CRPS represents an abnormal response which amplifies the effects of the injury.
In some cases, CRPS develops as a result of a nerve injury, while in other cases there is no nerve injury, but rather a soft tissue injury. In either case, the condition itself is way out of proportion to the original injury and it may persist long after the injury has healed. In fact CRPS has been known to develop following a mere paper cut.
Why does the swelling develop?
CRPS frequently involves swelling and discolouration of the skin. This is because it affects not only the nerves, but also blood vessels and the immune system. In CRPS there are abnormalities in small nociceptor nerve fibres which carry messages to the brain about noxious stimuli such as cuts and burns (these nerves were formally known as pain receptors, but this is not accurate as pain is an experience produced 100% in the brain). These small nerve fibres also connect to local blood vessels. As these nerve fibres become over-sensitive and hyperactive, they secrete chemicals at their endings which stimulate abnormalities in blood vessels and immune cells leading to inflammation. The blood vessels dilate (open wider) and leak fluid into the surrounding tissue, causing the skin to become red and swollen. The swelling causes the underlying muscles to become starved of oxygen and nutrients, causing pain and damage in both muscles and joints.
This abnormal activity in the peripheral nerves also triggers abnormal activity in the spinal cord and the brain. This can lead to disorders in brain function which may in turn increase the sensitivity of the peripheral nerves in a vicious circle, making the dysfunction worse. Because pain is a construct of the brain and depends on activation of a large number of different parts of the brain, this sensitisation can involve areas involved in emotion, perception, self-awareness, thinking and memory and motor control.
CRPS also affects the immune system. High levels of inflammatory chemicals have been found in the tissues of people with CRPS. These contribute to the redness, swelling, and warmth reported by many patients. It is interesting that CRPS is more common in individuals with other inflammatory and autoimmune conditions such as asthma.
So why exactly is this happening?
There are many different theories about what causes CRPS. It has been attributed to damage to nerve fibres, an inflammatory process, an auto-immune process, dysfunction of the fight/flight response, increased sensitivity in the brain, and reorganisation of the part of the brain associated with sensation. In fact the problem with many of these theories is that they attempt to compartmentalise something which is quite clearly a multi-system disorder. Like other chronic pain conditions, CRPS is best seen as a biopsychosocial condition, ie a condition which develops partly because of stress. There is preliminary evidence, for instance, that CRPS patients are more likely to have suffered a major life event before developing the condition.
And what about diagnosis and treatment?
The Royal College of Physicians point out that “Prompt diagnosis and early treatment are required to avoid secondary physical problems related to disuse of the affected limb and the psychological consequences of living with undiagnosed chronic pain.” Unfortunately CRPS is often misdiagnosed and it may be some time before the patient gets a correct diagnosis. So if you think you may be suffering from CRPS get medical help quickly
Treatment of CRPS should be multi-disciplinary involving physiotherapy and occupational therapy. Patient education is vital, as it has been found that the patient’s understanding of a painful condition can lead to improvements in pain, and besides education is important if the patient is to manage their condition appropriately. Your doctor may prescribe anti-inflammatories and pain relief medication to help reduce swelling and pain. In certain cases the doctor may prescribe anti-convulsants such as gabapentin as these have been found to be useful for pain relief where the pain is due to nerve injury.
A very different approach to the treatment of CRPS is by working directly with the brain itself. This approach is drug-free and includes the use of graded motor imagery and mirror therapy which can help in desensitising the brain. These treatment methods are now available here at BHIC as part of the BrainWorks chronic pain programme.
Sorrel Pindar, Registered Osteopath