In searching for new human pain models that more closely resemble clinical pain states, the capsaicin pain model has emerged as a viable model for both inflammatory and neuropathic pain states. A principal benefit of the capsaicin model is that it allows study of two different pain processes, primary and secondary hyperalgesia. Primary hyperalgesia is characterized by spontaneous pain and both heat and mechanical hyperalgesia. In addition, it is likely the result of activation and sensitization of both peripheral and central nociceptors. In contrast, secondary hyperalgesia is characterized by only mechanical hyperalgesia and is caused by the sensitization of central nociceptive neurons. Previous research utilizing the capsaicin pain model has primarily focused on the neural properties with little focus on the impact of affective states on capsaicin-related pain processes. The present study examined the impact of a noise stressor on both primary and secondary hyperalgesia. Results indicated that the effects of the noise stressor impacted secondary hyperalgesia, but not primary hyperalgesia.
