Assessment of experimentally induced pain. Old and new methods.

The term "algesimetry" refers to the experimental triggering and the quantitative recording of pain sensations in man. Since clinical pain and experimentally induced pain differ in important ways, the value of this type of research has often been questioned. A clear definition of target areas to be investigated is a prerequisite for successful future efforts in this area. Algesimetric methods, which may aid neurologic diagnosis, are not necessarily suited for testing analgesics. Tests or test batteries that lend themselves to the study of aspirin-type analgesics are not necessarily the most appropriate for the evaluation of narcotic analgesics. If algesimetry is to become an important instrument in clinical pharmacology, it is necessary to design tests that are sensitive to the effects of known analgesics (standards), with the consideration of different dosages and kinetics. Old and new methods for inducing pain are discussed, such as heat, cold, electrical and mechanical stimulation. With regard to the measurement of pain reactions, objective processes--in particular the method of recording evoked potentials--are compared with subjective processes. Special attention is paid to processes that involve several dimensions of pain. The selection of subjects is discussed, as are the possible clinical applications of algesimetric methods.