Pain
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When opioid therapy is initiated for a new pain condition, it may be unknown whether the pain will persist beyond the time of tissue healing. The aim of this study was to determine the prevalence of prescription patterns indicating persistent and/or problematic opioid use in a cohort of opioid-naive patients starting therapy with weak opioids. Data were drawn from the nationwide Norwegian Prescription Database. ⋯ Of these subjects, 686 patients were dispensed more than 365 DDDs of opioids in 2008 and are probably persistent users. There were 191 subjects who met our criteria for probable problematic opioid use. In a cohort of new opioid users who started treatment with weak opioids, only 0.3% and 0.08% developed prescription patterns indicating persistent opioid use and problematic opioid use, respectively.
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This systematic investigation of the neurocognitive correlates of complex regional pain syndrome (CRPS) in a single case also reports agnosia for object orientation in the context of persistent CRPS. We report a patient (JW) with severe long-standing CRPS who had no difficulty identifying and naming line drawings of objects presented in 1 of 4 cardinal orientations. In contrast, he was extremely poor at reorienting these objects into the correct upright orientation and in judging whether an object was upright or not. ⋯ The neuroanatomical correlates are discussed. The patient had no structural brain lesion, raising the possibility that nonstructural reorganisation of cortical networks may be responsible for his deficits. Other patients with CRPS may have related neurocognitive defects.
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The neuropeptide bradykinin (BK) sensitizes nociceptor activation following its release in response to inflammatory injury. Thereafter, the bioactivity of bradykinin is controlled by the enzymatic activities of circulating peptidases. One such enzyme, the metalloendopeptidase EC3.4.24.15 (EP24.15), is co-expressed with bradykinin receptors in primary afferent neurons. ⋯ In addition, bradykinin-induced sensitization of TRPV1 activation was increased in the presence of the EP24.15/16 inhibitor JA-2. Furthermore, behavioral analyses illustrated a significant dose-response relationship between JA-2 and bradykinin-mediated thermal hyperalgesia. These results indicate an important physiological role for the metallopeptidases EP24.15 and EP24.16 in regulating bradykinin-mediated sensitization of primary afferent nociceptors.