The objective measurement of pain using a motor-performance task.

An objective method for measuring endogenous pain in the wrist which originates in cervicobrachial disorders was improved. The method employed the plate-pushing task, which was reported previously (Taniguchi and Satow 1988a, b). The first improvement was achieved by introducing a load to be placed on the wrist while subjects were pushing the plate. In this way, it became easier to induce pain caused by disorders in the wrist. Another improvement was a new procedure by which a subject was told to change her pressure against a balance as instructed. This made it possible to identify the degree of pressure exerted which produce pain. Effects of dominance of hands, and of ordering the trials so as to begin with the dominant hand and switch to non-dominant, or vice versa in the tests were also examined, but were found to be not significant. Finally, the new method proved to be highly useful as an objective method for measuring pain of this sort because the method could produce very similar conditions to those associated with ordinary pain causing motion.