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Effect of Static and Dynamic Heat Pain Stimulus Profiles on the Temporal Dynamics and Interdependence of Pain Qualities, Intensity, and Affect

¹Division of Brain, Imaging and Behaviour—Systems Neuroscience, Toronto Western Research Institute, University Health Network, ²Institute of Medical Science and ³Department of Surgery, University of Toronto, Toronto, Ontario, Canada

Submitted 23 April 2008; accepted in final form 7 August 2008

Acute and chronic pains are characterized by a particular constellation of pain qualities, such as burning, aching, stinging, or sharp feelings. However, the temporal pattern of specific pain qualities and their relationship with pain and affect is not well understood. In addition, little is known about how the temperature time course of the stimulus impacts the temporal dynamics of pain qualities and the relationship between pain qualities. Therefore we applied two types of stimuli to the feet of 16 healthy subjects, each calibrated to evoke a similar pain magnitude (50/100): static stimulus held at constant intensity and dynamic stimulus increased in intensity in small steps. Stimulus runs consisted of three 30-s stimuli (either static or dynamic) with an interstimulus interval of 60 s. Continuous on-line ratings of pain, burning, sharp, stinging, cutting, and annoyance were obtained in separate runs, and the evoked responses were characterized by within-stimulus adaptation (early: 0- to 15-s peak vs. late: 25- to 40-s peak) and by their temporal properties (time to onset, peak, and end). The temporal profile of the burning sensation was similar to the pain and annoyance evoked by the static and dynamic stimuli. However, the sharp, stinging and cutting sensations attenuated in response to the static stimuli (P < 0.01) but intensified along with pain and affect in response to the dynamic stimuli (P < 0.05), whereas there was no attenuation in the evoked profiles of pain (P = 0.61), annoyance (P = 0.27), or burning quality (P = 0.27). These data demonstrate that specific pain qualities with known differences in underlying mechanisms have distinct temporal dynamics that depend on the stimulus intensity dynamics.