Complex regional pain syndrome (CRPS) is an umbrella term covering different clinical scenarios. It is a rare condition
characterized by regional persisting pain, disproportionate to its underlying cause, usually coupled with sensorimotor,
vasomotor, sudomotor, and trophic abnormalities. Different forms of CRPS have been identified: CRPS type I (algodystrophy);
CRPS type II (causalgia); CRPS-NOS (not otherwise specified), and CRPS with remission of some features
(CRSF). The pathophysiology of algodystrophy is probably related to multiple mechanisms, such as abnormal inflammation,
vasomotor dysfunction, and maladaptive neuroplasticity. In most cases this condition is related to traumatic injuries
or fractures, most frequently located at the distal upper limb, although in some patients no related triggering factor can
be found. Algodystrophy occurrence after non-orthopedic surgery or procedures, such as percutaneous transluminal
coronary angioplasty, cardiac ablation, hemodialysis, or transplantation, is rare and underestimated. Imaging can assist
clinicians in the very challenging differential diagnosis of CRPS. To prevent severe and disabling consequences, international
guidelines suggest a prompt multimodal approach to algodystrophy, including pharmacological (bisphosphonates,
particularly neridronate) and non-pharmacological (i.e., rehabilitation interventions) measures.
