Sex differences in temporal summation but not sensory-discriminative processing of thermal pain.

Gender differences in experimental pain sensitivity have been widely investigated, and the results generally indicate that females exhibit greater sensitivity to noxious stimuli than males. However, results using thermal pain procedures have been inconsistent, with some studies reporting greater responses among females and other studies reporting no gender differences. The present study investigated gender differences in thermal pain perception using several different psychophysical procedures. Twenty-seven females and 22 males underwent thermal testing, including: determination of thermal pain threshold and tolerance, a thermal discrimination procedure, real-time magnitude estimates of heat pulses, and temporal summation of thermal pain. The results indicated lower thermal pain threshold and tolerance and greater temporal summation of thermal pain among females, but no gender differences in thermal discrimination or real-time magnitude estimates of discrete heat pulses. These findings suggest that gender differences in thermal pain perception may be more robust for sustained, temporally dynamic thermal stimuli with a strong C-fiber component.