Pain
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In this clinical and neurophysiological study, we examined the clinical characteristics and underlying mechanisms of neuropathic pain related to multiple sclerosis. A total of 302 consecutive patients with multiple sclerosis were screened for neuropathic pain by clinical examination and the DN4 tool. In patients selected for having ongoing extremity pain or Lhermitte's phenomenon, we recorded somatosensory evoked potentials, mediated by Aβ non-nociceptive fibres, and laser evoked potentials, mediated by Aδ nociceptive fibres. ⋯ The prevalence of pain that we found, which was lower than that reported in previous studies, may reflect the lesser disease severity in our patients. Neurophysiological data show that whereas ongoing extremity pain is associated with spinothalamic pathway damage, Lhermitte's phenomenon is related to damage of non-nociceptive pathways. These findings may be useful in designing a new therapeutic approach to neuropathic pain related to multiple sclerosis.
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Opioids are essential to the management of pain in many patients, but they also are associated with potential risks for abuse, overdose, and diversion. A number of efforts have been devoted to the development of abuse-deterrent formulations of opioids to reduce these risks. ⋯ Because of the many types of individuals who may be exposed to opioids, an opioid formulation will need to be studied in several populations using various study designs to determine its abuse-deterrent capabilities. It is recommended that the research conducted to evaluate abuse deterrence should include studies assessing: (1) abuse liability, (2) the likelihood that opioid abusers will find methods to circumvent the deterrent properties of the formulation, (3) measures of misuse and abuse in randomized clinical trials involving pain patients with both low risk and high risk of abuse, and (4) postmarketing epidemiological studies.
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Analgesia is particularly susceptible to placebo responses. Recent studies in humans have provided important insights into the neurobiology underlying placebo-induced analgesia. However, human studies provide incomplete mechanistic explanations of placebo analgesia because of limited capacity to use cellular, molecular, and genetic manipulations. ⋯ We found that conditioned (placebo) responding bore 3 of the hallmarks of placebo-induced analgesia: (1) strong interanimal variability in the response, (2) suppression by the opiate antagonist naloxone (5mg/kg subcutaneously), and (3) a positive predictive relationship between the unconditioned analgesic effect and the conditioned (placebo) effect. Because of the operant nature of the assay and the use of only a mild noxious thermal stimulus, we suggest that these results provide evidence of placebo-induced analgesia in a preclinical model that utilizes an affective behavioral end point. This finding may provide opportunities for invasive preclinical studies allowing greater understanding of placebo-induced analgesia, thus paving the way for avenues to harness its benefits.
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There are few studies that have looked at the occurrence of co-morbid conditions amongst patients with back problems. This study assesses the association between of a range of co-morbidities and the labour force participation rates of 45- to 64-year-old Australians with back problems. Logistic regression models were applied to the 2003 Survey of Disability, Ageing and Carers (SDAC) data to look at the relationship between chronic back problems, labour force participation and comorbidities. ⋯ For example, an individual with back problems and heart disease is more than 10 times more likely to be out of the labour force than those with back problems alone (OR=10.90, 95% CI=2.91-40.79, P=.0004). Amongst conditions that have a significant impact on labour force participation rates, back problems and multiple co-morbidities are significantly more likely to cause persons with these conditions to be out of the labour force than those with back problems alone or those with no chronic health condition. It is important to consider which co-morbidities an individual has when assessing the impact of back problems on labour force participation, as co-morbid conditions vary in their association with labour force participation.