CRPS commonly occurs after an injury as minor as having blood drawn, or a sprain. Other times, it may be the result of a more significant injury such as surgery, a fracture, immobilization with casting or splinting, or the result of a stroke.
Risk factors for developing CRPS include immobilization of the affected limb with a cast, splint or sling; smoking; genetics; and psychological factors.
There is no specific test to make the diagnosis of CRPS. The following symptoms or factors are usually considered when making the diagnosis of CRPS
- triggering injury or cause for immobilization
- continuing pain, allodynia, or hyperalgesia that is out of proportion to what would be expected by the injury or immobilisation
- evidence at some time of odema or change in skin blood flow
Other associated symptoms may include
- atrophy of the hair, nails, skin, and muscles
- alteration in hair growth
- loss of joint mobility
- impairment of motor function, including weakness, tremor
The course of CRPS is commonly divided into 3 stages.
In the acute or first stage the affected region is painful, tender, swollen, and warm. Also, sweating, discoloration (usually red), and an increase in hair and nail growth is evident.
The second stage is characterized by burning pain, allodynia, hyperalgesia, coolness of the skin, hair loss, changes in skin such as paleness, and brittle or cracked nails. Allodynia is when pain is felt from stimulation which is not usually painful, such as light touch or a breeze. Experiencing pain from the sheet over an affected foot or leg is an example. Hyperalgesia is an increased, prolonged pain response. This is from something that would typically result in only mild discomfort.
The third stage is permanent and is characterized by dystrophy or defective growth of bones or tissue. It consists of muscle atrophy or shrinkage, bone density (calcium) loss, contracture, edema, and limited range of motion of the affected joints. Pain is worsened by any kind of touch and movement of the affected limb.
Sometimes only two stages are used to describe this condition. Temperature of the skin is either warm (stage 1), or cold (stage 2).
Treatment may involve a multidisciplinary approach. Nerve blocks, drug therapy, physical therapy, behavioural therapy, and psychological support may be included.
An article in journal of pain from 2009 showed one hundred and two CRPS patients were assessed at on average 5.8 years (range: 2.1 to 10.8) from onset. CRPS patients displayed higher symptom and sign prevalence sensory, vasomotor, sudomotor, and motor/trophic changes than controls without the condition. Sixteen percent reported the CRPS was still progressive, whereas 31% were incapable of working. Patients in the poorest outcome cluster more often had their upper extremity affected.