In: Chronic Pain: a Health Policy Perspective

To the person in pain, its existence is self evident and utterly convincing. However, the scientist who tries to demonstrate how the pain comes about knows that he or she is taking on a far more complex challenge than the study of other biological phenomena. What then, can science tell us about what is happening in the cells and tissues of the body during this uniquely human experience? Scientists study pain at several levels of the nervous system. At the site of injury special nerve cell endings called nociceptors, which have been waiting for exactly this moment, respond to one of a myriad of unpleasant stimuli such as heat, pressure and inflammation, by sending a rapid and urgent signal that something is wrong. Shortly afterwards potent chemicals are released by crushed and broken cells which are detected by other nerves and amplify the pain signal. This whole process is called nociception, the change in the senses induced by a noxious stimulus. Activation of nociceptors can often lead to pain, but this is not always the case. A person may perceive a given event as merely annoying, mildly painful, or excruciating, based not only on the size of the trauma, but also on their thoughts, attitudes and context. An elite athlete or soldier in battle, for example, may be so focussed on the task at hand that he or she does not even notice his broken finger until the moment has long passed. Pain is thus the result of integrated neural input. It is highly individual and subjective in nature, ofte