title: Secondary heat hyperalgesia detected by radiant heat stimuli in humans: evaluation of stimulus intensity and duration.
abstract: Diverging observations on secondary hyperalgesia to heat stimuli have been reported in the literature. No studies have investigated the importance of heat stimulus intensity and duration for the assessment of secondary heat hyperalgesia. The present study was designed to investigate systematically (1) if pain sensitivity to radiant heat stimuli (focused Xenon light) is altered in the area of secondary punctuate hyperalgesia induced by intradermal injection of capsaicin and (2) if heat stimulus duration and intensity had an influence on the ability to detect secondary heat hyperalgesia. Pain ratings to radiant heat stimuli from a focused xenon lamp were assessed within the area of secondary punctuate hyperalgesia in fifteen volunteers before and after intradermal injection of capsaicin. The stimulus conditions were systematically varied between three intensity levels (0.8, 1.0 and 1.2 x heat pain threshold (PT)) and four duration steps (200, 350, 500 and 750 ms). The present study shows that long duration (350-750 ms) and low intensity (0.8 and 1.0 x PT) radiant heat stimuli were adequate to detect secondary heat hyperalgesia.
authors.affiliation: Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, Denmark.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sumikura
authors.forename: Akiko
authors.initials: A
authors.lastname: Miyazawa
authors.forename: Aysen
authors.initials: A
authors.lastname: Yucel
authors.forename: Ole K
authors.initials: OK
authors.lastname: Andersen
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
mesh_terms: D000328:Adult; D002211:Capsaicin; D006358:Hot Temperature; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced / Q000503:physiopathology*; D007271:Injections, Intradermal; D008297:Male; D010146:Pain / Q000503:physiopathology; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D013997:Time Factors
chemical_list: D002211:Capsaicin