Complex regional pain syndrome (CRPS) is a painful condition affecting a limb, associated with sensory, motor, autonomic, skin and bone abnormalities. Symptoms will present differently in different people. It is diagnosed using Budapest Criteria. 

• Bone abnormalities include localised osteoporosis in parts of the affected limb, which usually resolves spontaneously
• Skin abnormalities include reversible changes in texture or appearance of the skin, eg the skin might appear thin or shiny