European journal of pain : EJP
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The aim was to study the introduction of the new low dose transdermal buprenorphine (LD-TD-BUP) in Norway, particularly with regard to former use and co-medication with other potentially addictive drugs. The nationwide Norwegian Prescription Database contains information on all prescription drugs dispensed to individual non-institutionalised patients, and we may follow all individuals who received LD-TD-BUP (Norspan) after marketing on the Norwegian market on 15/11/05. We studied all prescriptions of opioids and other potentially addictive drugs to patients receiving at least two LD-TD-BUP prescriptions during 2004-2006. ⋯ Of the LD-TD-BUP users who received more than one prescription, 60% co-medicated with at least one other potentially addictive drug, and 24% with at least two. In the multivariate analysis, the variables associated with a higher likelihood of using co-medicated drugs were: previous use of benzodiazepines/carisoprodol relative risk RR=16.7 (95% CI 10.4-26.9), previous use of opioids RR=4.0 (1.9-8.7) and younger age 20-40 years RR=1.9 (1.6-2.3). So far, it is questionable whether the introduction of LD-TD-BUP actually has stabilised opioids consumption or whether it has complicated and increased the consumption of potentially addictive drugs.
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Comparative Study
Stress and thermoregulation: different sympathetic responses and different effects on experimental pain.
Stress and thermoregulation both activate the sympathetic nervous system (SNS) but might differently affect pain. Studies investigating possible interactions in patients are problematic because of the high prevalence of SNS disturbances in patients. We therefore analyzed the influence of these different sympathetic challenges on experimentally-induced pain in healthy subjects. ⋯ The control tasks neither activated the SNS nor altered pain perception. Our results suggest that (1) different patterns of sympathetic activation can be recorded after stress and thermoregulatory challenges and (2) that only stress is able to interfere with sensation of experimental pain. Whether SNS activation is causally responsible for analgesia needs to be further investigated.
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There is increasing evidence that spinal glial cells play an important role in chronic pain states. However, so far no data on the role of microglia in muscle pain are available. The aim of the present study was to investigate the involvement of spinal microglial cells in chronic muscle pain. ⋯ This indicates that microglial cells were activated by the myositis and withdrew their processes. Chronic intrathecal administration of minocycline or anti TNF-alpha with an osmotic mini-pump largely normalised the inflammation-induced changes in spontaneous exploratory behaviour and attenuated the hypersensitivity to mechanical stimulation. Both the immunohistochemical and behavioural data show that spinal microglial cells are involved in nociceptive processes in the cause of a chronic muscle inflammation.
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Recent research suggests that changes in cortical structures can contribute to the pathophysiology of Complex Regional Pain Syndrome (CRPS). This review provides an overview of studies showing cortical involvement in CRPS, including mislocalizations of tactile stimuli, changes in size and organization of the somatosensory map, changes in motor cortex representation and body perception disturbances. In addition, we review experimental treatment approaches, such as mirror therapy and motor imagery programs, aimed at restoring the integrity of neural processing in the sensory-motor cortex in individuals with CRPS. The intervention effects are promising and can be theoretically motivated on the basis of established principles of neural organization, although important questions concerning the precise neural mechanisms of action remain unanswered.