Sorel M, et al. - Researchers investigated assessed the value of three-phase bone scintigraphy (TPBS) to predict the analgesic efficacy of ketamine therapy in complex regional pain syndrome (CRPS). They observed a positive correlation of the relative hyperfixation of the radioactive tracer in the limb region concerned by CRPS in phases 2 and 3 vs phase 1 of TPBS, with the analgesic efficacy of ketamine. For the first time, TPBS was shown to have potential predictive value regarding ketamine therapy outcome. Findings suggested the possible involvement of “peripheral” mechanisms related to tissue inflammation and bone remodeling in the analgesic action of ketamine; these were not restricted to “central” mechanisms.