Complex Regional Pain Syndrome (CRPS) can occur following a minor injury to a limb, such as a sprain, fracture, wound, infection or surgical procedure. It is believed that it occurs as a consequent of vasomotor instability (poor regulation of the constriction and dilation of blood vessels). The exact causes of this condition are unclear, however it is generally accepted that the causes are complex and can include multiple possible factors. These factors include autonomic nervous system dysfunction (the ANS controls bodily functions that are out of conscious control, such as digestion, sweating, and heart-rate), neurogenic inflammation (inflammation caused by a release of substances from the nervous system), central sensitisation and plasticity changes in the brain (the nervous system begins functioning in a persistent state of high reactivity), all triggered by an injury, leading to chronic pain.
There are two types of CRPS: type 1 and type 2. They present with the same symptoms, the difference being that type 2 has an identifiable nerve injury, often affecting the distribution of a single nerve, while type 1 does not. CRPS affects people of all ages, although it is not common in children under 10 years of age. Women are three times more likely to develop CRPS.
The main presenting symptom of CRPS is pain that is out of proportion with the severity of the injury. For CRPS type 1, there are three distinct stages:
- Acute stage (0-3 months): patient presents with severe burning pain; the foot or lower limb will appear be warm and swollen; the joints will feel stiff; affects an entire area, such as the whole foot, and not a single dermatome or myotome. Symptoms may worsen if touched or if the patient is emotionally stressed. Radiographs (X-rays) may show early signs of bones becoming demineralised.
- Dystrophic stage: may last several months; affected area is no longer warm and oedematous (swollen), but firm, cool, and cyanotic (blue-ish); pain becomes constant and made worse by any stimulus; radiographs will show diffuse osteoporosis; flexion contractures of the digits may begin to develop (toes start becoming “pulled down”); the disease process is still reversible at this stage.
- Atrophic stage: if the patient does not receive effective treatment, the condition may enter the third stage and become irreversible; pain may remain, reduce, or disappear; skin and subcutaneous tissues (below the skin) may atrophy; flexion contractures of the foot become irreversible; radiographs show advanced osteoporosis, giving the bones a “ground glass appearance”.
Early recognition and treatment is essential to prevent the patient suffering permanent harm and reduced quality of life. A diagnosis is usually made by presenting symptoms and physical examination, as well as by radiographic imaging (X-ray, MRI). Treatment involves a combination of the following:
- Physical therapy: in the early stages, it is imperative to try and prevent abnormal joint contractures and muscle wasting. Heat applications, massage, therapeutic exercises, and occupational therapy are used for this purpose. The extremity should never be immobilised, such as by using a cast or boot that prevents movement of the joints.
- Pain management: fortnightly sympathetic nerve blocks can be used (using local anaesthetic to reduce aberrant nerve impulses); NSAIDs can be used; short-term use of corticosteroid injections can be helpful in the early stages; narcotic (opioid) pain killers should be avoided as this can lead to dependency; tricyclic antidepressants and anticonvulsants may help with depression and nerve-mediated pain; surgery may be used in severe cases (sympathectomy); therapy, such as psychological therapy or CBT are also likely to be of benefit. Acupuncture may also be helpful, although the painful area itself would not be needled (this could be very painful), instead needling points close to this area, ideally along the same myotomes and dermatomes, or “acupuncture meridians”, depending on the style of acupuncture being offered. If this isn’t possible, then the central effects of acupuncture alone may still be helpful in cases of CRPS.