Management of Chronic Pain

Pain is a leading reason that people seek medical care. Annually, pain is estimated to burden the U.S. economy with $100 billion in direct costs and $61 billion in productivity losses. These losses, which amount to a mean of 4.6 hours weekly, are largely due to diminished performance at work.1 Perhaps more significant, but more difficult to quantify, is the emotional distress and diminished quality of life that pain inflicts on individuals and their loved ones.What Is Pain? Pain, as defined by the International Association for the Study of Pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”2 Thus, pain is an experience that comprises a physical sensory component and an affective cognitive component. The physical element involves a nociceptive, neuropathic, or inflammatory stimulus that is transmitted via the spinal cord to the thalamus and then to areas of the cerebral cortex, where it is perceived. Acute pain serves a biological purpose as an alert to potential, immediate, or ongoing injury.Chronic pain is pathologic, serves no biological purpose, and can result from peripheral sensitization, in which processes (such as changes in gene expression in the dorsal root ganglia) augment the synthesis of various peripheral nociceptors. In turn, inputs to the dorsal horn of the spinal cord are amplified, leading to activation of N -methyl-d-aspartate (NMDA) receptors and subsequent …