Molecular signature of complex regional pain syndrome (CRPS) and its analysis.

INTRODUCTION: Complex Regional Pain Syndrome (CRPS) is a rare, but often disabling pain disease. Biomarkers are lacking, but several inflammatory substances have been associated with the pathophysiology. This review outlines the current knowledge with respect to target biomolecules and the analytical tools available to measure them. Areas covered: Targets include cytokines, neuropeptides and resolvins; analysis strategies are thus needed for different classes of substances such as proteins, peptides, lipids and small molecules. Traditional methods like immunoassays are of importance next to state-of-the art high-resolution mass spectrometry techniques and 'omics' approaches. Expert commentary: Future biomarker studies need larger cohorts, which improve subgrouping of patients due to their presumed pathophysiology, and highly standardized workflows from sampling to analysis.