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Heat hyperalgesia in humans: assessed by different stimulus temperature profiles
Aysen Yucel1, Ole K Andersen, Jesper Nielsen
1Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark.
European Journal of Pain (London, England)
|August 6, 2002
Summary
The rate of temperature increase affects pain perception after capsaicin-induced hyperalgesia. Slower heating rates (1°C/s) intensified pain more than faster rates (5-8°C/s) in the primary hyperalgesic area.
Area of Science:
- Neuroscience
- Pain Research
- Sensory Physiology
Background:
- Capsaicin induces localized pain and hypersensitivity.
- Understanding heat pain perception is crucial for pain management.
- The role of temperature increase rate in hyperalgesia requires further investigation.
Purpose of the Study:
- To examine how the rate of temperature increase influences evoked pain intensity.
- To investigate heat hyperalgesia before and after capsaicin application.
- To differentiate effects in primary and secondary hyperalgesic areas.
Main Methods:
- Healthy volunteers received topical capsaicin on one forearm and served as controls for the other.
- A computer-controlled contact stimulator applied heat stimuli at varying rates (1.0, 5.0, 8.0°C/s) and temperatures.
- Pain intensity was rated before and after hyperalgesia induction.
Main Results:
- Capsaicin significantly increased pain ratings at 36-42°C in the primary hyperalgesic area.
- Slower heating rates (1°C/s) resulted in higher pain ratings compared to faster rates (5-8°C/s) at 36-42°C.
- Heat hyperalgesia was also observed in the secondary hyperalgesic area for temperatures of 45-49°C.
Conclusions:
- Hyperalgesia to suprathreshold heat stimuli occurs in the secondary hyperalgesic area.
- C-fibers are critical for primary heat hyperalgesia.
- The rate of temperature increase is a significant factor in modulating heat pain perception.