title: Time dependent differences in pain sensitivity during unilateral ischemic pain provocation in healthy volunteers.
abstract: Plurisegmental endogenous pain inhibitory mechanisms related to diffuse noxious inhibitory controls (DNIC) were demonstrated in animal experiments to act on multireceptive neurons of the entire cord outside the conditioned segment without any side differences. Human experiments have demonstrated altered pain sensitivity to pressure, heat and electrical stimulation during heterotopic noxious conditioning stimulation (HNCS). The purpose of the study was to examine if side and/or time differences in pain thresholds and suprathreshold pain sensitivity for pressure and heat, respectively, could be detected during HNCS. Perception thresholds to pressure and heat pain as well as the sensitivity to suprathreshold pressure (SPP) and heat pain (SHP) were assessed in 18 healthy volunteers bilaterally at the thighs before, during and following ischemia-induced pain of the left forearm (HNCS). The assessments started with either the right (10 subjects) or the left thigh (8 subjects). During HNCS the pressure pain threshold increased significantly (p<0.001) on both sides alike. No significant difference in the magnitude of the altered pressure pain threshold was seen between sides for the first or the lastly assessed side. On the lastly assessed side only SPP and SHP increased significantly on both sides alike (p<0.02 and p<0.03, respectively), without magnitude differences between sides. During unilateral HNCS of the left arm, a time factor was demonstrated only for alterations in suprathreshold pain sensitivity, without any differences in magnitude between sides. Therefore, the results have implications for future design of HNCS-related experimental and clinical studies.
authors.affiliation: Section of Clinical Pain Research, Department of Surgical Science, Karolinska Institute/University Hospital, SE-171 76 Stockholm, Sweden.
authors.forename: Birgitta
authors.initials: B
authors.lastname: Tuveson
authors.forename: Ann-Sofie
authors.initials: AS
authors.lastname: Leffler
authors.forename: Per
authors.initials: P
authors.lastname: Hansson
mesh_terms: D000328:Adult; D001132:Arm / Q000098:blood supply*; D005260:Female; D007839:Functional Laterality; D006358:Hot Temperature; D006801:Humans; D007511:Ischemia / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017288:Pain Threshold; D011312:Pressure; D011930:Reaction Time; D012016:Reference Values; D013848:Thigh; D014111:Tourniquets