Pain
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The true incidence of neuropathic pain is unknown, but it is believed to be under-diagnosed and treated inadequately, despite the availability of drugs with proven efficacy. Our objective was to report the epidemiology and drug treatment of neuropathic pain as managed by UK primary care physicians. A descriptive analysis of the epidemiology of incident post-herpetic neuralgia (n=12,386); trigeminal neuralgia (8268); phantom limb pain (451) and painful diabetic neuropathy (4719) and prescription treatment at diagnosis from computerised UK general practice records (GPRD): January 1992 to April 2002. ⋯ In 2600 patients followed to stable therapy, there was a median of one to two drug changes. We provide the primary care managed incidence of four neuropathic pain conditions. For commonly prescribed treatments, changes in therapy are less frequent when initial therapy was with antidepressants or anticonvulsants rather than conventional analgesics.
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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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Randomized Controlled Trial Comparative Study
Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: a prospective randomized controlled study.
The effectiveness of lumbar fusion for chronic low back pain after surgery for disc herniation has not been evaluated in a randomized controlled trial. The aim of the present study was to compare the effectiveness of lumbar fusion with posterior transpedicular screws and cognitive intervention and exercises. Sixty patients aged 25-60 years with low back pain lasting longer than 1 year after previous surgery for disc herniation were randomly allocated to the two treatment groups. ⋯ The mean difference between treatments after adjustment for gender was -7.3 (95% CI -17.3 to 2.7, p=0.15). The success rate was 50% in the fusion group and 48% in the cognitive intervention/exercise group. For patients with chronic low back pain after previous surgery for disc herniation, lumbar fusion failed to show any benefit over cognitive intervention and exercises.
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Randomized Controlled Trial
Psychophysical study of the effects of topical application of menthol in healthy volunteers.
Cold hyperalgesia is a major clinical phenomenon, but validated experimental models are still lacking for humans. Topical menthol application has recently been proposed as a possible model for the study of cold pain. We characterized the psychophysical effects of 30% l-menthol in ethanol on glabrous skin in 39 healthy subjects, using a double-blind, randomized, crossover design, with ethanol as a control. ⋯ No subject displayed signs of skin irritation or redness. These data suggest that 30% menthol application may be a useful experimental model for studies of cold hyperalgesia in humans. The absence of local skin reactions also makes this test potentially suitable for use in patients.
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Randomized Controlled Trial
Effects of intensity of electroacupuncture upon experimental pain in healthy human volunteers: a randomized, double-blind, placebo-controlled study.
Electroacupuncture is commonly used for pain relief. Despite an extensive evidence-base guiding the selection of stimulation parameters, little methodologically robust research exists regarding the level of intensity required to provide effective doses. This study investigated the hypoalgesic effects of two stimulation intensities compared to placebo on pressure pain thresholds (PPTs) in pain-free humans. ⋯ The control group displayed stable PPT readings over time. No significant differences were observed between the placebo and control groups. These findings suggest that high-intensity levels may be important in optimal dose selection.