ABSTRACT
Pain is defined as an “unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage” (1). This definition avoids tying pain to any stimulus, because pain is always subjective and may be present with or without the presence of tissue damage or any likely pathophysiological cause. Furthermore, the severity of pain may or may not correlate with the severity of any tissue damage. For example, viral gastroenteritis usually results in severe abdominal pain, whereas ovarian cancer rarely causes pain until very late in the course. The lack of correlation of severity of pain and that of disease is mechanistic, which means that one cannot conclude that severe pain in the presence of minimal disease signifies a psychological etiology. It is important that this principle be remembered during the clinical evaluation and treatment of patients with pain.
