title: Relationships between the intensity and duration of Peltier heat stimulation and pain magnitude.
abstract: Ramp-and-hold heat stimulation with a Peltier thermode is a standard procedure for quantitative sensory testing of human pain sensitivity. Because myelinated and unmyelinated nociceptive afferents respond preferentially to changing and steady temperatures, respectively, ramp-and-hold heat stimulation could assess processing of input from A-delta nociceptors early and C nociceptors late during prolonged thermal stimulation. In order to evaluate the progression from dynamic change to a steady temperature during prolonged Peltier stimulation, recordings of temperatures at the probe-skin interface were obtained. First, recordings of temperature during contact-and-hold stimulation (solenoid powered delivery of a preheated thermode to the skin) provided an evaluation of heat dissipation from the beginning of stimulation, uncontaminated by ramping. The heat-sink effect lasted up to 8 s and accounted in part for a slow increase in pain intensity for stimulus durations of 1-16 s and stimulus intensities of 43-59 °C. Recordings during longer periods of stimulation showed that feedback-controlled Peltier stimulation generated oscillations in temperature that were tracked for up to 75 s by subjects' continuous ratings of pain. During 120-s trials, sensitization of pain was observed over 45 s after the oscillations subsided. Thus, long-duration stimulation can be utilized to evaluate sensitization, presumably of C nociception, when not disrupted by oscillations in thermode temperature (e.g., those inherent to feedback control of Peltier stimulation). In contrast, sensitization was not observed during 130.5 s of stimulation with alternately increasing and decreasing temperatures that repeatedly activated A-delta nociceptors.
authors: Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL 32610-0244, USA. vierck@mbi.ufl.edu
authors: Charles J
authors: CJ
authors: Vierck
authors: Andre P
authors: AP
authors: Mauderli
authors: Joseph L
authors: JL
authors: Riley
mesh_terms: D000328:Adult; D000368:Aged; D055592:Biophysical Phenomena / Q000502:physiology*; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D010812:Physical Stimulation; D012881:Skin Temperature / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult