Complex Regional Pain Syndrome (CRPS) is a chronic pain condition that most often develops after a physical trauma, such as a fracture, surgery, or stroke, typically affecting a single limb. The defining characteristic of CRPS is persistent, severe pain that is disproportionate to the severity of the original injury. This condition involves a dysfunction within the central and peripheral nervous systems. The abnormal signaling leads to an exaggerated response to pain and inflammation, involving neurogenic inflammation and altered pain perception. CRPS is traditionally categorized into three sequential stages of progression, each marked by distinct changes in symptoms and physical presentation.
Stage I: Early Symptoms and Progression
The initial phase, often called the acute stage, typically lasts from a few weeks up to three months following the inciting injury. A hallmark of this stage is the onset of intense, deep-seated pain described as burning, throbbing, or aching, which is far greater than expected for the original trauma. This severe pain is frequently accompanied by allodynia, where a non-painful stimulus, like a light touch, causes excruciating discomfort.
Physical changes are prominent due to vasomotor dysfunction and neurogenic inflammation. The affected limb may appear swollen, and the skin often shows dramatic temperature and color fluctuations, shifting between red, purple, or mottled. Increased sweating (hyperhidrosis) and changes in hair and nail growth are also common signs. Early intervention during this acute stage is beneficial, as symptoms are often more responsive to treatment.
Stage II: Chronic Pain and Tissue Changes
If the condition progresses, it enters the dystrophic phase, which can extend from three to six months and sometimes much longer. In this stage, the pain typically becomes more constant and widespread. The characteristics of swelling also change; the initially soft edema becomes firmer, more fixed, and localized as tissue changes occur.
The skin begins to show more pronounced trophic changes, losing the fluctuating warm appearance of Stage I. It commonly becomes cool to the touch, pale, mottled, or bluish, reflecting a sustained change in blood flow regulation. The skin may also take on a shiny, tight, or thin texture.
Muscle atrophy begins as the patient avoids moving the painful limb, leading to disuse and weakness. Joint stiffness increases markedly, and the early changes in hair and nails reverse; hair growth slows down, and nails can become severely brittle, cracked, or ridged. Patchy bone demineralization also starts to develop.
Stage III: Irreversible Atrophy
The final stage is the atrophic phase, which can begin around six months to a year after the onset of symptoms and may become permanent. By this point, the physical changes are fixed and severe, representing a culmination of the earlier stages. The affected limb exhibits severe muscle wasting, where muscle mass visibly diminishes.
Mobility is profoundly limited by the development of contractures, which are permanent shortening of muscles and tendons, resulting in severely restricted joint movement. The skin in this chronic stage is thin, dry, and fragile, and bone loss has progressed to significant osteoporosis. While chronic pain may continue, the physical alterations represent a fixed state of disability.
Identifying and Treating Complex Regional Pain Syndrome
Diagnosing CRPS is a clinical process; no single laboratory test or scan confirms the condition. Diagnosis relies on a thorough patient history and physical examination, using the Budapest criteria. These criteria require the presence of continuing, disproportionate pain and specific symptoms across four categories: sensory, vasomotor (color/temperature), sudomotor/edema (sweating/swelling), and motor/trophic (movement/tissue changes).
The treating physician must also rule out other potential causes, as CRPS is a diagnosis of exclusion. Management requires a comprehensive, multimodal approach that addresses the physical and neurological aspects of the disease. Physical therapy is frequently cited as the single most impactful treatment, focusing on maintaining movement and function.
Pharmacological interventions include medications aimed at neuropathic pain, such as certain anticonvulsants or antidepressants. Specific procedures like sympathetic nerve blocks may also be used to interrupt pain signals. Psychological support is incorporated to manage the emotional burden of chronic pain.