Pain
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The present study examined the role of catastrophizing in predicting levels of pain and disability in a sample of individuals who had sustained soft-tissue injuries to the neck, shoulders or back following work or motor vehicle accidents. Participants were 86 (27 men, 59 women) consecutive referrals to the Atlantic Pain Clinic, a multidisciplinary treatment centre for the management of persistent pain disorders. Findings revealed that catastrophizing, measured by the Pain Catastrophizing Scale (PCS; Sullivan, M. ⋯ In addition, catastrophizing was associated with disability independent of the levels of depression and anxiety. The rumination subscale of the PCS was the strongest predictor of pain and disability. Theoretical and clinical implications of the findings are discussed.
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The mechanisms by which nerve growth factor (NGF) induces thermal hyperalgesia and neutrophil accumulation have been investigated in the rat. Thermal nociceptive thresholds in rat hind paw were measured as the time taken for paw withdrawal from a heat source and neutrophil accumulation was measured in hind paw and dorsal skin samples using a myeloperoxidase assay. NGF (23-80 pmol intraplantar (i.pl.) injection) induced a significant (P < 0.05, n = 6-16) thermal hyperalgesia at 5 h after injection and significant neutrophil accumulation (P < 0.05, n = 6) was observed with NGF (40 pmol). ⋯ The 5-lipoxygenase inhibitor ZM230487 (10 nmol co-injected with NGF) significantly attenuated neutrophil accumulation and hyperalgesia induced by NGF; unlike the histamine and 5-hydroxytryptamine antagonists (mepyramine and methysergide) which were without effect at the times measured. Furthermore, depletion of circulating neutrophils (using a rabbit anti-rat neutrophil antibody) abolished NGF induced hyperalgesia. These results indicate that neutrophils, which accumulate in response to a 5-lipoxygenase product, play a crucial role in NGF-induced hyperalgesia.
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Abnormal return of cutaneous sensibility is common after burn injuries and many patients complain of painful and/or paresthetic sensations in their healed wounds. However, little is known about the exact nature and severity of these problems. The present study was designed to provide a quantitative evaluation of the cutaneous sensibility in burned patients. ⋯ When symptomatic and asymptomatic sites were compared, significant deficits were observed in the tactile modality (touch-pressure). Other significant predictors of chronic sensory problems were burn depth and patients' age. Pathophysiological mechanisms of diminished sensibility in burned and unburned skin as long as several years after the injury are discussed along with those implicated in pain and paresthesia problems reported by the patients.
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Mexiletine is widely used for the treatment of neuropathic pain although its site(s) of action remain unclear. Here we have studied the effect of spinal administration of mexiletine (10-1000 microg) on the spontaneous and peripherally evoked responses of spinal neurones of nerve injured (selective ligation of spinal nerves L5-L6; SNL) rats. Sham controls for the surgical intervention were performed. ⋯ In addition, the mechanical punctate von Frey 9 and 50 g evoked neuronal responses of the SNL rats, but not sham operated rats, were significantly reduced by spinal mexiletine (F5,57 = 4.3, P < or = 0.002 and F5,52 = 6.1, P < or = 0.001). This pharmacological study suggests that following nerve injury there is a novel mexiletine sensitive spinal substrate which contributes to Adelta-fibre and C-fibre, but not Abeta-fibre, somatosensory transmission. This central action may underlie some of the clinical efficacy of mexiletine in the treatment of neuropathic pain states.
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In this review epidemiological studies concerning chronic benign pain among adults are discussed. To this end, studies focusing on chronic pain, reporting prevalences at a population or primary health care level, including subjects aged between 18 and 75 years have been collected and analyzed. ⋯ Nor method used (telephone survey, postal survey, nor definition of chronicity (>1 month; >3 months; >6 months) clearly explained the differences in prevalence in the various studies. Implications for future research are discussed.