TNF and complex regional pain syndrome: Pro-inflammatory cytokines such as interleukin (IL)-1β, IL-2, IL-6, and tumor necrosis factor-α (TNF-α), as well as neuropeptides like calcitonin gene-related peptide (CGRP), bradykinin, and substance P, contribute to the intense inflammatory response following trauma or injury, ultimately instigating the development of CRPS (60, 61).