pain, unpleasant or hurtful sensation resulting from stimulation of nerve endings. The stimulus is carried by nerve fibers to the spinal cord and then to the brain, where the nerve impulse is interpreted as pain. The excessive stimulation of nerve endings during pain is attributed to tissue damage, and in this sense pain has protective value, serving as a danger signal of disease and often facilitating diagnosis. Unlike other sensory experiences, e.g., response to touch or cold, pain may be modified by sedatives and nonsteroidal anti-inflammatory drugs or, if unusually severe, by opioid narcotics. Recently, patient-controlled analgesic techniques have been introduced, in which patients have the option of injecting small quantities of narcotic type analgesics to control their own pain. Microprocessor-controlled injections may be made through intravenous catheters, or through a catheter into the epidural (covering of the spinal cord) area. If such treatments do not suffice and if the cause of the pain cannot be removed or treated, severing a nerve in the pain pathway may bring relief.
Pain is occasionally felt not only at the site of stimulation but in other parts of the body supplied by nerves in the same sensory path; for example, the pain of angina pectoris or coronary thrombosis may extend to the left arm. This phenomenon is known as referred pain. Subjective or hysterical pain originates in the sensory centers of the brain without stimulation of the nerves at the site of the pain.
Progress has been made in the management of chronic pain and in the education of patients and physicians in such techniques as biofeedback, acupuncture, and meditation and the appropriate use of narcotics and other medications. Using advanced medical-imaging technology, researchers have now located multiple pain centers in the cerebral cortex of the brain, offering promise of possible improvements in measuring and managing pain.
See F. T. Vertosick, Jr., Why We Hurt: The Natural History of Pain (2000).