Pain
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Diabetes can induce a bewildering list of sensory changes, including alteration in pain sensitivity. Painful diabetic neuropathy is refractory to most common analgesics. This study examined the effect of a p38alpha MAPK inhibitor, SD-282, on mechanical allodynia, thermal hyperalgesia, and formalin-evoked nociception in streptozotocin-induced diabetic rats. ⋯ Repeated administration of 45 mg/kg SD-282 attenuated flinching behaviors during the quiescent period and the second phase of the formalin response in diabetic rats. Acute and repeated administration of 15 or 45 mg/kg SD-282 had no effect on mechanical, thermal or formalin responses in age-matched control rats. These results indicate a potential therapeutic value of p38alpha MAPK inhibitors in the treatment of aberrant pain sensitivity produced by diabetes.
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Randomized Controlled Trial Clinical Trial
Effect of acupuncture treatment on chronic neck and shoulder pain in sedentary female workers: a 6-month and 3-year follow-up study.
The study was carried out to examine whether acupuncture treatment can reduce chronic pain in the neck and shoulders and related headache, and also to examine whether possible effects are long-lasting. Therefore, 24 female office workers (47+/-9 years old, mean+/-SD) who had had neck and shoulder pain for 12+/-9 years were randomly assigned to a test group (TG) or a control group (CG). Acupuncture was applied 10 times during 3-4 weeks either at presumed anti-pain acupoints (TG) or at placebo-points (CG). ⋯ Three years after the treatments TG still reported less pain than before the treatments (Pw < 0.001) contrary to what CG did (Pb < 0.04) The degree of headache fell during the treatment period for both groups, but more for TG than for CG (Pb=0.02) Three years after the treatments the effect still lasted for TG (Pw < 0.01) while the degree of headache for CG was back to the pre-treatment level (Pb < 0.001) PPT of some muscles rose during the treatments for TG and remained higher 6 months after the treatments (Pw < 0.05) which contrasts the situation for CG. Adequate acupuncture treatment may reduce chronic pain in the neck and shoulders and related headache. The effect lasted for 3 years.
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The disinhibition hypothesis of post-stroke central pain (CPSP) suggests that 'the excessive response (dysesthesia/hyperalgesia/allodynia) is accompanied by a em leader loss of sensation' resulting from a lesion of a 'lateral nucleus' of thalamus or of 'cortico-thalamic paths' [Brain 34 (1911) 102]. One recent elaboration of this hypothesis proposes a submodality specific relationship, such that injury to a cool-signaling lateral thalamic pathway disinhibits a nociceptive medial thalamic pathway, thereby producing both burning, cold, ongoing pain and cold allodynia. The current study quantitatively evaluated the sensory loss and sensory abnormalities to discern submodality relationships between these sensory features of CPSP. ⋯ The most dramatic case of cold allodynia occurred in a patient who had a normal detection threshold for cold. Individuals with cold hypoesthesia, strictly contralateral to the cerebro-vascular accident (CVA or stroke), were often characterized by the presence of burning, cold, ongoing pain, and by the absence, not the presence, of cold allodynia. Overall, these results in CPSP suggest that tactile allodynia occurs in disturbances of thermal/pain pathways that spare the tactile-signaling pathways, and that cold hypoesthesia is neither necessary nor sufficient for cold allodynia.
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Electronic diary assessment methods offer the potential to accurately characterize pain and other daily experiences. However, the frequent assessment of experiences over time often results in missing data. It is important to identify systematic reasons for missing data because such a pattern may bias study results and interpretations. ⋯ The most common self-reported reasons for missing interviews were failure to hear the computer alarm (49%) and inconvenient time (21%). Although there was some suggestion that persistent negative mood and stress were associated with missing electronic interviews in a subgroup of patients, on the whole, the patient demographic and clinical characteristics, treatment, and daily fluctuations in pain, activity interference, mood, and stress were not associated significantly with missing daily electronic interviews. The results provide further support for the use of electronic diary methodology in pain research.
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We reported recently that redox agents, including the endogenous amino acid L-cysteine, modulate T-type Ca2+ currents in primary sensory neurons in vitro, and alter mechanical and thermal nociception in peripheral nociceptors in vivo in intact animals [Neuron 31 (2001) 75]. Here, we studied the effects of locally applied redox agents (L-cysteine and 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB) on thermal hyperalgesia in animals with neuropathic pain due to chronic constrictive injury (CCI) of the sciatic nerve. We found that, following injection into the peripheral receptive fields, the endogenous reducing agent L-cysteine increased thermal hyperalgesia in a dose-dependent manner in rats with CCI of the sciatic nerve as well as in sham-operated rats. ⋯ Mibefradil, a potent and preferential T-type Ca2+ channel blocker, abolished L-cysteine-induced increase in thermal hyperalgesia in both animal groups suggesting the involvement of T-type Ca2+ channels in peripheral nociception. These results indicate for the first time that redox modulation of T-type Ca2+ channels in rat peripheral nociceptors is operational in pain states caused by peripheral axonal injury. Since thermal hyperalgesia is a common symptom of axonal injury, locally applied oxidizing agents could be used as a novel treatment to ameliorate neuropathic pain.