The chronic pain is a true emergency. In fact, the study "Pain in Europe 2005" showed that 26% of the Italian population is suffering by it. Chronic pain can be benign, when caused by a tissular damage, or malignant when cancer-related. The study of the pain has made a lot of progress in the last years. An example is the chemical neuromodulation, that interferes with the transmission of the pain afferences toward the brain, through the administration of chemical substances in the spinal or cranial compartment in well selected patients. This allows the use of doses lower than those required for other ways of administration, with less collateral effects and a more rapid response.