THRESHOLDS FOR THE PERCEPTION OF PRESSURE, SHARPNESS, AND MECHANICALLY EVOKED CUTANEOUS PAIN - EFFECTS OF LATERALITY AND REPEATED TESTING

Twenty-four healthy human subjects provided thresholds for their perce ption of pressure, sharpness, and pain. Mechanical forces were applied to the dorsal surface of the digits with flat-tipped probes of variou s sizes. Thresholds (expressed as force) increased with increasing pro be size, as previously described. There was no evidence of a lateralit y difference for any of the thresholds. There was a trend for increasi ng thresholds with repeated testing, but this trend was not statistica lly significant for the group as a whole. Examination of individual su bjects' thresholds over time revealed that 27% showed significant incr eases in pain threshold over the 15 days of testing. In contrast, only 6% of subjects showed significant increases in sharpness or pressure thresholds over the same period. Thus, whereas most subjects exhibited stable pain thresholds, approximately one-fourth showed significant i ncreases in pain threshold over time. We conclude that for evaluating regional dysesthesia or hemidysesthesia, a right-left difference in pa in thresholds will provide a more sensitive and reliable measure than absolute pain threshold.