Articles: hyperalgesia.
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Acute pain management in opioid-dependent persons is complicated because of tolerance and opioid-induced hyperalgesia. Very high doses of morphine are ineffective in overcoming opioid-induced hyperalgesia and providing antinociception to methadone-maintained patients in an experimental setting. Whether the same occurs in buprenorphine-maintained subjects is unknown. ⋯ Buprenorphine subjects, compared with controls, were hyperalgesic (cold pressor test), did not experience antinociception, despite high plasma morphine concentrations, and experienced respiratory depression. Clinical implications are discussed.
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Allodynia is prevalent in adults with migraine and has been associated with long disease duration and severe course. Studies of the pediatric population are sparse. The aim of this study was to evaluate the rate of cephalic cutaneous allodynia in children and adolescents within the first 6 months of migraine onset and to identify associated clinical and migraine-related parameters. ⋯ Cephalic cutaneous allodynia may occur in children and adolescents already in the first 6 months of migraine onset. Contrary to adult studies, we found no association of allodynia with migraine frequency or long disease duration. Allodynia was significantly associated with migraine with aura, female gender, and awakening pain. A genetic tendency may contribute to the appearance of allodynia in the pediatric age group.
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Post-traumatic headache is the most common and long-lasting impairment observed following mild traumatic brain injury, and frequently has migraine-like characteristics. The mechanisms underlying progression from mild traumatic brain injury to post-traumatic headache are not fully understood. The aim of this study was to develop a mouse model of post-traumatic headache and identify mechanisms and novel targets associated with this disorder. ⋯ Overall, we have established a mouse model of post-traumatic headache and identified the delta opioid receptor as a novel therapeutic target for this disorder.
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The sensitizing effect of capsaicin has been previously characterized using laser and contact heat evoked potentials (LEPs and CHEPs) by stimulating in the primary area of hyperalgesia. Interestingly, only CHEPs reveal changes consistent with notion of peripheral sensitization (i.e., reduced latencies). The aim of this study was to investigate contact heat stimulation parameters necessary to detect peripheral sensitization related to the topical application of capsaicin, and therefore significantly improve the current method of measuring peripheral sensitization via CHEPs. ⋯ These findings suggest that earlier recruitment of capsaicin-sensitized afferents occurs between 35 and 42°C, as stimulations from 42°C baseline were unchanged by capsaicin. This is in line with reduced thresholds of type II A-delta mechanoheat (AMH) nociceptors following sensitization. Conventional CHEP stimulation, with a baseline temperature below 42°C, is well suited to objectively detect evidence of peripheral sensitization.