In complex regional pain syndrome (CRPS), which type is associated with nerve injury?

Complex Regional Pain Syndrome (CRPS) is classified into two main types based on the presence of nerve injury. CRPS I, also known as reflex sympathetic dystrophy (RSD), occurs without any identifiable nerve damage. This type typically arises following an injury or surgical procedure and is characterized by the presence of pain, swelling, and changes in skin temperature or color in the affected limb.

In contrast, CRPS II, sometimes referred to as causalgia, specifically involves a clear and identifiable nerve injury. This type of CRPS develops after a nerve has been damaged, leading to similar symptoms to CRPS I but with an underlying nerve injury confirmed through clinical assessment or diagnostic imaging. The presence of nerve injury in CRPS II is a critical distinction that significantly influences treatment approaches and management strategies.

The other types mentioned in the options (CRPS III and CRPS IV) are not commonly used classifications in the current literature regarding CRPS and do not represent established or archetypal categories as CRPS I and II do. In summary, CRPS II is correctly associated with nerve injuries, making it the appropriate answer in this context.