Pain
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Comparative Study
Reduced heat sensitivity and epidermal nerve fiber immunostaining following single applications of a high-concentration capsaicin patch.
Capsaicin-containing plant extracts have been used as topical treatments for a variety of pain syndromes for many centuries. Current products containing capsaicin in low concentrations (usually 0.025-0.075% w/w) have shown efficacy against a variety of pain conditions in clinical studies. However, in order to produce significant analgesic effects, these formulations require frequent re-dosing, often as much as three to five times daily for several weeks. ⋯ The results show a significant reduction of heat, but not cold, sensitivity and reduction of ENF immunostaining with high-capsaicin concentration patch applications for 60 or 120 min, compared to placebo patch applications. Application sites exposed to low-capsaicin concentration (0.04%w/w) patches for 120 min or high-concentration patches for 30 min were not significantly different from placebo with respect to either thermal threshold detection or ENF immunostaining. The ability of a single 60 min high-concentration patch application to mimic effects produced by prolonged exposure to low-concentration capsaicin creams suggests a new approach to the management of chronic pain syndromes.
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Comparative Study
Can one predict the likely specific orofacial pain syndrome from a self-completed questionnaire?
To estimate the prevalence of orofacial pain (OFP) by specific diagnostic subgroups in the general population. Cross-sectional population study. General medical practice in South East Cheshire, UK. ⋯ The estimated prevalence in the general population of musculoligamentous/soft tissue type of OFP was 7%, dentoalveolar 7% and neurological/vascular 6%. This study has derived a statistical model to classify participants with OFP into three broad groups (musculoligamentous/soft tissue, dentoalveolar and neurological/vascular) based on questionnaire information about OFP (OFP chronicity, location and verbal descriptors of pain). It is potentially useful in large population studies of OFP, where a clinical examination is not possible, however, further validation of its performance in large populations are necessary.
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Comparative Study
Spatial summation of heat pain within and across dermatomes in fibromyalgia patients and pain-free subjects.
The mechanisms of spatial summation of pain (SSP) include pain coding dependent on impulse frequency and the number of recruited central neurons. However, SSP may also be influenced by pain inhibitory mechanisms, such as diffuse noxious inhibitory controls. Abnormal interactions between pain inhibitory mechanisms and SSP may be relevant for chronic pain conditions such as fibromyalgia (FM) and may help explain why widespread pain is characteristic for this chronic pain syndrome. ⋯ Furthermore, SSP was more pronounced within one dermatome such as that of the index finger than across several dermatomes of the hand. These results were similar for both FM and NC subjects. Thus, mechanisms of SSP, including possible inhibitory factors that limit this relevant pain mechanism, appear to be similar for both FM and NC subjects.
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Clonidine, an alpha-2 adrenergic agonist, is an extremely potent antinociceptive agent. However, the therapeutic utility of systemic clonidine for the treatment of pain is limited by centrally mediated side effects including sedation, hypotension and rebound hypertension. Given that alpha-2 adrenoceptors are expressed on the peripheral and central terminals of nociceptive fibers, we administered clonidine topically in order to avoid central effects. ⋯ Tolerance to the antinociceptive actions of clonidine was not blocked by topical administration of the NMDA antagonist, ketamine. In conclusion, topical administration of clonidine elicits antinociception by blocking the emerging pain signals at peripheral terminals via alpha-2 adrenoceptors without producing the undesirable central side effects observed following the systemic administration. The ineffectiveness of topical ketamine to block topical clonidine antinociceptive tolerance suggests that peripheral NMDA receptors do not mediate local clonidine antinociceptive tolerance.
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Our objective was to determine the efficacy and safety of valdecoxib (a cyclo-oxygenase 2 inhibitor) in the treatment of arthritis. Randomised, controlled trials comparing 10 or 20mg valdecoxib with placebo or non-steroidal anti-inflammatory drugs (NSAIDs) in patients with active osteoarthritis or rheumatoid arthritis. The manufacturer provided clinical trial reports. ⋯ At an appropriate dose valdecoxib was as effective as NSAIDs in osteoarthritis and rheumatoid arthritis. There were fewer gastrointestinal adverse event withdrawals and endoscopically detected ulcers. Convincing evidence of reduced major gastrointestinal adverse events could not be addressed by the trials.