Perception of noxious and innocuous heat stimulation among healthy women and women with fibromyalgia: association with mood, somatic focus, and catastrophizing.

Recent studies have demonstrated that persons with fibromyalgia display abnormal processing of different types of painful stimulation, suggesting the disorder is characterized by a central pain-processing deficit not limited specifically to muscle pain. In the present study, 20 women with fibromyalgia and 20 normal, healthy women were compared on measures of pressure pain stimulation and response to contact thermal heat at both noxious and innocuous intensities. Women with fibromyalgia displayed significantly lower pressure pain thresholds at 18 tender point locations as defined by the American College of Rheumatology criteria, as well as lower pressure pain thresholds at five control sites. Women with fibromyalgia had significantly lower heat pain thresholds and tolerances when stimulated on the volar surface of the left forearm. When examining visual analog ratings of intensity and unpleasantness to constant stimuli, a multivariate analysis of variance performed on these ratings indicated that there were significant main effects of level of stimulation and group. Individual analysis of variances at each temperature revealed significant differences between the groups in pain intensity and unpleasantness ratings at both noxious and innocuous temperatures. Multiple regression analyses indicated that greater pain catastrophizing and diagnosis of fibromyalgia were associated with decreased pain thresholds and tolerances in the entire sample, whereas, self-report of depressive symptoms was associated with increased thresholds and tolerances. Self-report of somatic symptoms was not associated with these measures. These findings indicate that persons with fibromyalgia display altered perception of both pressure and thermal stimulation, even at innocuous levels. They also suggest that catastrophic thoughts about pain may play a role in increased pain perception in this population.