Pain
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Noxious stimulation of the rat's face evokes intense face grooming with face wash strokes almost exclusively directed to the stimulated area (e.g. Clavelou et al., Neurosci. Lett., 14 (1989) 3263-3270). ⋯ Only formalin-injected rats displayed significantly more face grooming activity directed to the affected infraorbital nerve territory than unstimulated control rats. Non-painful sensory disturbances (especially mineral oil application) induced an initial bout of directed face grooming; this response was transient and short-lasting. These observations suggest that directed face grooming can be used as a sign of unilateral facial pain in freely moving rodents; unilateral non-painful facial sensory disturbances do not lead to intense and persistent directed face grooming.
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Gabapentin (GP) has been shown to have antihyperalgesic properties and the site of drug action is reported to be the central nervous system. The goal of the present study was to determine whether GP also has a peripheral site of action. ⋯ The antihyperalgesic effect of GP (1) was not due to a systemic effect since animals injected with 600 microg GP in one hindpaw and 2% formalin into the contralateral hindpaw developed nociceptive behaviors which were no different than those seen in animals injected with formalin alone; (2) was not due to a local anesthetic effect since needle sticks within the drug-injected region evoked paw withdrawal behavior which was not different from pre-drug levels; (3) was blocked by 20 microl D-serine but not by L-serine. Although the mechanism of action of GP has yet to be elucidated, these results indicate that GP has a peripheral site of action and thus may offer a novel therapeutic agent for topical or local treatment of pain of peripheral origin.
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This study used streptozotocin (STZ; 50 mg/kg i.p.) diabetic rats and monitored weekly thermal and mechanical nociceptive thresholds for 8 weeks diabetes. Rats developed mechanical hyperalgesia as soon as 2 weeks after STZ injection. Thermal nociceptive threshold was not altered up to 8 weeks after STZ injection. ⋯ An increased release of glutamate and activation of the NMDA receptor, would maintain the hyperalgesic state. Reduced activity of both opioidergic and GABA(B)ergic inhibitory systems, might exacerbate the increased excitation thus contributing to the ongoing pain. It is suggested that NMDA receptor antagonists may constitute an alternative therapy for diabetic neuropathic pain.
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Randomized Controlled Trial Clinical Trial
A fitness programme for patients with chronic low back pain: 2-year follow-up of a randomised controlled trial.
The aim of this study was to assess the long-term effect of a supervised fitness programme on patients with chronic low back pain. The design of the study was a single blind randomised controlled trial with follow-up, by postal questionnaire, 2 years after intervention. The Oswestry Low Back Pain Disability Index was used as the outcome measure to assess daily activity affected by back pain. ⋯ Between group comparisons demonstrated a statistically significant difference in disability scores between the treatment and control group (mean difference 5.8, 95% confidence interval 0.3, 11.4 P < 0.04). This study supports the current trend towards a more active treatment approach to low back pain. We have demonstrated clinical effectiveness of a fitness programme 2 years after treatment but this needs to be replicated in a larger study which should include a cost effectiveness analysis, further analysis of objective functional status and a placebo intervention group.
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Randomized Controlled Trial Clinical Trial
The NMDA receptor antagonist amantadine reduces surgical neuropathic pain in cancer patients: a double blind, randomized, placebo controlled trial.
Neuropathic pain is often severe, persistent, and responds poorly to analgesic medications. Recent evidence suggests that N-methyl-D-aspartate (NMDA) receptor antagonists may be effective in the treatment of neuropathic pain. The present trial was designed to test the efficacy of acute administration of the NMDA receptor antagonist amantadine in relieving surgical neuropathic pain in patients with cancer. ⋯ Amantadine, but not the placebo, also reduced 'wind up' like pain (caused by repeated pinpricking) in four patients. We conclude that amantadine infusion is a safe and effective acute treatment for surgical neuropathic pain in cancer patients. Further trials with long-term oral or parenteral amantadine treatment should be conducted.