Complex regional pain syndrome is an uncommon form of chronic pain that usually affects an arm or leg. Complex regional pain syndrome typically develops after an injury, surgery, stroke or heart attack. Because Complex Regional Pain syndrome is a systemic disease, any organ can potentially be affected.
CRPS has the unfortunate honour of being described as one of the most, if not the most, painful long term medical condition. The pain associated with CRPS is continuous, and it is widely recognised that it can be heightened by emotional or physical stress.
Studies indicate that there are psychosocial factors to CRPS (such as reduced quality of life and impaired occupational function) in addition to related psychological problems (including increased depression and anxiety).
The wikipedia entry for complex regional pain reads:
Complex regional pain syndrome (CRPS), formerly reflex sympathetic dystrophy or causalgia, is a chronic systemic disease characterized by severe pain, swelling, and changes in the skin. CRPS is expected to worsen over time. It often initially affects an arm or a leg and often spreads throughout the body; 92% of patients state that they have experienced a spread and 35% of patients report symptoms in their whole body. Recent evidence has led to the conclusion that Complex Regional Pain Syndrome is a multifactorial disorder with clinical features of neurogenic inflammation, nociceptive sensitisation (which causes extreme sensitivity or allodynia), vasomotor dysfunction, and maladaptive neuroplasticity, generated by an aberrant response to tissue injury. Treatment is complicated, involving drugs, physical therapy, psychologic treatments and neuromodulation and usually unsatisfactory, especially if begun late.
CRPS is associated with dysregulation of the central nervous system and autonomic nervous system resulting in multiple functional loss, impairment and disability. The International Association for the Study of Pain has proposed dividing CRPS into two types based on the presence of nerve lesion following the injury.