The CRPS literature regarding the role of IL-6 and TNF-α in the chronic stages is controversial and based on substantial variability in patient characteristics (i.e., acute vs. chronic), testing methods (i.e., CSF, blister fluid, mRNA, and blood), and type of control group (healthy vs. limb pain or the contralateral noninvolved limb) [93]. The gene discussed is IL6; the disease is complex regional pain syndrome.