Pain
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Randomized Controlled Trial
Predictive factors for 1-year and 5-year outcome for disability in a working population of patients with low back pain treated in primary care.
Many patients seeking primary care for low back pain continue to report disability several years after their initial visit. The aims of this study were to assess the independent predictive value of a number of potential predictive factors for disability at the 1-year and 5-year follow-ups, and to examine whether prediction models were improved by replacing baseline health-state-related variables with corresponding variables after treatment. A further aim was to describe possible differences between those on sick leave, early retirement or disability pension, and those who were not. ⋯ For those without disability the corresponding figure was 9% (n=8/92). Being a woman, duration of the current episode, similar problems during the previous 5 years, exercise level before the current episode, pain frequency at baseline, and disability after treatment emerged as predictive factors for disability at the 5-year follow-up. Replacing baseline health-state-related measures with corresponding measures after the treatment period, and adding physical-activity-related and possibly work-related factors might improve the likelihood of predicting future disability.
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Clinical Trial
Physical and psychological factors maintain long-term predictive capacity post-whiplash injury.
Higher initial levels of pain and disability, older age, cold hyperalgesia, impaired sympathetic vasoconstriction and moderate post-traumatic stress symptoms have been shown to be associated with poor outcome 6 months following whiplash injury. This study prospectively investigated the predictive capacity of these variables at a long-term follow-up. Sixty-five of an initial cohort of 76 acutely injured whiplash participants were followed to 2-3 years post-accident. ⋯ The latter two groups showed only persistent deficits in cervical muscle recruitment patterns. Higher initial NDI scores (OR 1.00-1.1), older age (OR 1.00-1.13), cold hyperalgesia (OR 1.1-1.13) and post-traumatic stress symptoms (OR 1.03-1.2) remained significant predictors of poor outcome at long-term follow-up (r2=0.56). The robustness of these physical and psychological factors suggests that their assessment in the acute stage following whiplash injury will be important.
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Randomized Controlled Trial
Reduction of intractable deafferentation pain by navigation-guided repetitive transcranial magnetic stimulation of the primary motor cortex.
The precentral gyrus (M1) is a representative target for electrical stimulation therapy of pain. To date, few researchers have investigated whether pain relief is possible by stimulation of cortical areas other than M1. According to recent reports, repetitive transcranial magnetic stimulation (rTMS) can provide an effect similar to that of electrical stimulation. ⋯ Results indicated a statistically significant effect lasting for 3 hours after the stimulation of M1 (p<0.05). Stimulation of other targets was not effective. The M1 was the sole target for treating intractable pain with rTMS, in spite of the fact that M1, S1, preM, and SMA are located adjacently.
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Experimental models of peripheral nerve injury have been developed to study mechanisms of neuropathic pain. In the spared nerve injury (SNI) model in rats, the common peroneal and tibial nerves are injured, producing consistent and reproducible pain hypersensitivity in the territory of the spared sural nerve. In this study, we investigated whether SNI in mice is also a valid model system for neuropathic pain. ⋯ We tested two variants of the SNI model and found that injuring the tibial nerve alone induces mechanical hypersensitivity, while injuring the common peroneal and sural nerves together does not induce any significant increase in mechanical sensitivity in the territory of the spared tibial nerve. SNI induces a mechanical allodynia-like response in mice and we believe that our improved method of assessment and data analysis will reveal additional internal and external variability factors in models of persistent pain. Use of this model in genetically altered mice should be very effective for determining the mechanisms involved in neuropathic pain.
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Management of acute pain remains a significant clinical problem. In preclinical studies, CB2 cannabinoid receptor-selective agonists inhibit nociception without producing central nervous system side effects. The CB2 receptor-selective agonist AM1241 produces antinociceptive effects that are antagonized by CB2, but not CB1, receptor-selective antagonists, suggesting that activation of CB2 receptors results in antinociception. ⋯ The effects of morphine were not altered in CB2-/- compared to CB2+/+ mice. These data strongly suggest that AM1241 produces antinociception in vivo by activating CB2 cannabinoid receptors. Further, they confirm the potential therapeutic relevance of CB2 cannabinoid receptors for the treatment of acute pain.