Neural processing of cold-induced pain relief in heat allodynia (fMRI study)

Background: Thermal (heat) allodynia or hyperalgesia is a core symptom of neuropathic pain syndromes resulting from sensitization of peripheral C-fiber afferents (primary hyperalgesia). Neural processing in the brain is distinctly different in capsaicin-induced thermal allodynia, when compared to perceptionally identical pain intensities elicited by thermal stimuli on normal skin. The goal of this study was to identify central neural mechanisms of pain relief from primary hyperalgesia by using thermal cooling. We hypothesized that cooling might fascilitate endogenous descending inhibitory mechanisms. Methods: We…