Pain and its modulation. Part 2. efferent mechanisms.

Recent studies of central nervous system effects on pain and on its efferent modulation have created new theories and have led to direct clinical applications that may in time eclipse more classical interventions. In this review electrical stimulation analgesia is presented as a paradigm of how basic science work has been applied clinically to produce some of the most exciting advances in recent years in the treatment of chronic pain. Opiate receptors and analgesia are presented in relationship to the descending inhibitory systems used in electroanalgesia. Neuromodulators and neurotransmitters important in pain modulation through complex inhibitory and excitatory pathways are discussed, with the roles of B-endorphin, enkephalin, serotonin, and other important biogenic amines being stressed. The neuropharmacology of pain as it is currently understood clinically suggests that psychotropic interventions may be quite useful in treating difficult pain problems.