VEGFA and complex regional pain syndrome: The presence of high NMDA excitatory amino acids (glutamate, glutamine, glycine, taurine, and arginine) and high levels of serotonin were present in CRPS patients [75]; elevated pro-excitatory amino acids such as L-Aspartate, L-glutamate, L-ornithine [15]; and vascular endothelial growth factor [57] were demonstrated in CRPS patients.