ABSTRACT
Pain is primarily a psychological experience. It is the most pervasive and universal form of human distress and it often contributes to dramatic reductions in the quality of life. As demonstrated repeatedly in the chapters to follow, it is virtually inevitable and a relatively frequent source of distress from birth to old age. Episodes of pain can vary in magnitude from events that are mundane, but commonplace, to crises that are excruciating, sometimes intractable, and not so common, but still not rare. The costs of pain in human suffering and economic resources are extraordinary. It is the most common reason for seeking medical care, and it has been estimated that approximately 80% of physician office visits involve a pain component ( Henry, 1999–2000).
