A model of clinical pain. Technique for evaluation of analgesic agents.

A method is described utilizing repetitive electrical stimulation for the production of long-term continuous pain which approaches the quality of clinical pain. This technique provides for on-line monitoring of actual power delivered to the subject. Incremental stimuli of high and low intensities were randomly superimposed on continuous painful background electrical stimulation. Subjects were studied in a triple crossover design with acupuncture, codeine and baseline treatments. Data were evaluated by Sensory Decision Theory (SDT) procedures. The codeine compound significantly raised the response criterion to higher intensity stimuli but did not effect perception of low intensity stimuli, indicating an analgesic but not an anesthetic effect. No significant differences were found between control and acupuncture results for either pain discriminability or pain report criterion. The results are discussed with regard to the physiological effects of electrical stimulation and the merits of this new stimulation technique.