Altered gut microbiome composition and function in individuals with complex regional pain syndrome.

Background: Complex regional pain syndrome (CRPS) is a chronic pain syndrome typically affecting a limb. It is characterized by severe spontaneous and evoked pain, along with vasomotor, autonomic, and motor signs and symptoms. Although dysregulation in several physiologic systems has been suggested in CRPS, including aberrant inflammatory and immune responses, vasomotor dysfunction, and nervous system changes, the pathophysiologic mechanisms underlying the syndrome remain elusive.