CRPS

Complex Regional Pain Syndrome (CRPS) is a chronic pain condition characterized by prolonged, disproportionate regional pain and a constellation of autonomic, motor, and trophic changes that follow tissue injury. It is divided into CRPS I (without confirmed nerve injury) and CRPS II (with a confirmed peripheral nerve injury).

Symptoms typically include persistent burning or aching pain, allodynia (pain from non-noxious stimuli), and hyperalgesia, often in one limb. Swelling, redness or pale, cool or warm skin, sweating changes, and hair or nail growth alterations may occur. Motor symptoms such as decreased mobility, tremor, dystonia, or weakness can appear, and trophic changes may develop over time.

Pathophysiology is not fully understood but is thought to involve peripheral and central sensitization, inflammatory and immune mediators, autonomic nervous system dysregulation, and maladaptive cortical reorganization. A triggering event is common, but not all patients have an ongoing injury.

Diagnosis relies on clinical assessment. The Budapest criteria require continuing pain disproportionate to the event, plus at least two symptoms in sensory, vasomotor, sudomotor/edema, or motor/trophic categories, and at least one sign in two categories found on examination. A thorough evaluation excludes other conditions; imaging and nerve studies may support but are not diagnostic.

Treatment is multidisciplinary and aims to relieve pain and restore function. Early physical or occupational therapy, graded motor imagery, and psychological support are central. Medications include NSAIDs, anticonvulsants, antidepressants, bisphosphonates, and sometimes topical agents. In refractory cases, interventions such as sympathetic blocks or neuromodulation (e.g., spinal cord stimulation) may be considered.

Prognosis varies; some improve over months with treatment, while others have persistent symptoms. CRPS is more common in women and often follows minor injury.