An observational study on the effect of S(+)-ketamine on chronic pain versus experimental acute pain in Complex Regional Pain Syndrome type 1 patients

The data indicate that while ketamine's effect on acute experimental pain is driven by pharmacokinetics, its effect on CRPS pain persisted beyond the infusion period when drug concentrations were below the analgesia threshold for acute pain. This indicates a disease modulatory role for ketamine in CRPS-1 pain, possibly via desensitization of NMDAR in the spinal cord or restoration of inhibitory sensory control in the brain.