Mechanisms and clinical management of pain.

Pain is an unpleasant, sensitive and emotional experience associated with or described in terms of tissue lesion, and may be acute or chronic. It may also be classified as nociceptive, neuropathic or psychogenic. Nociceptive pain involves the transformation of environmental stimuli into action potentials carried to the central nervous system, where they are modulated and integrated up to final interpretation in the cerebral cortex. Neuropathic pain may arise as a consequence of the direct lesion of axons, or of an increase in the production of neurotrophic factors. Chronic pain is always associated with anxiety and some degree of depression. Drug therapy should be selected according to its efficacy; nonetheless, the professional should also consider the tolerability and adverse effects that may occur, for example, in elderly individuals. It is necessary to emphasize the safety-considering the possibility of drug interactions-and define the posology to promote better adherence. However, the treatment of neuropathic pain should not be limited to the use of analgesic drugs, which are just one among several options enabling patients to participate in bio-psycho-social rehabilitation programs.