What is a characteristic sign of complex regional pain syndrome (CRPS)?

• A. Normal circulation in the affected area
• B. Allodynia
• C. Decreased muscle mass
• D. Weakness in the upper extremities

Answer: (B)

A key characteristic sign of complex regional pain syndrome (CRPS) is allodynia, which refers to the experience of pain in response to stimuli that typically do not provoke pain, such as light touch or temperature changes. This phenomenon is fundamentally tied to the altered pain processing often seen in CRPS, wherein the nervous system develops heightened sensitivity to sensory input in the affected area.

Allodynia can significantly impact a patient's quality of life, as normal activities become painful, contributing further to the cycle of disuse and consequent dysfunction. In the context of CRPS, this symptom highlights the complex interplay between the nervous system and pain perception, making it a distinct feature of the condition. The presence of allodynia often helps differentiate CRPS from other pain syndromes, emphasizing the unique pathophysiology underlying this disorder.

Other signs of CRPS can include changes in skin temperature, color, or texture, along with varying degrees of swelling. However, allodynia remains a hallmark feature and is critically important for clinical diagnosis and management strategies in patients presenting with symptoms consistent with CRPS.