TAC1 and complex regional pain syndrome: Neuropeptides like substance P and CGRP, released by sensitised nociceptive C-fibres,24 lead to neuroinflammation with increased cytokine production (TNF-α, interleukin-6) and proliferation or immigration of Langerhans and mast cells.4,15 The presence of IgG antibodies against autonomic nervous system receptors (β2-, α1A-adrenergic, and M2-muscarinic receptors) suggests an autoimmune component in some patients with CRPS.10,20 These mechanisms may collectively contribute to varying degrees of bone loss, independent of injury location and CRPS type.