European journal of pain : EJP
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In the context of neuropathic pain, the contribution of regeneration to the development of positive symptoms is not completely understood. Several efforts have been done to described changes in axotomized neurons, however, there is scarce data on changes occurring in intact neurons, despite experimental evidence of functional changes. To address this issue, we analysed by immunohistochemistry the presence of phosphorylated signal transducer and activator of transcription 3 (pSTAT3), an accepted marker of regeneration, within DRGs where axotomized neurons were retrogradely labelled following peripheral nerve injury. Likewise, we have characterized abnormal electrophysiological properties in intact fibres after partial nerve injury. ⋯ Positive symptoms in patients with peripheral neuropathies correlate to abnormal functioning of different subpopulations of primary afferents. Peripheral nerve damage triggers regenerating programs in the cell bodies of axotomized but also in non-axotomized nociceptors which is in turn, develop abnormal spontaneous and evoked discharges. Therefore, intact nociceptors have a significant role in the development of neuropathic pain due to their hyperexcitable peripheral terminals. Therapeutical targets should focus on inhibiting peripheral hyperexcitability in an attempt to limit peripheral and central sensitization.
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Randomized Controlled Trial
Dependence-like behaviour in patients treated for medication overuse headache: A prospective open-label randomized controlled trial.
Dependence-like behaviour may complicate withdrawal and increase risk of relapse of medication overuse headache (MOH). The most effective treatment for reducing dependence-like behaviour is unknown. ⋯ Withdrawal combined with preventive medication from start is the treatment strategy that reduces dependence-like behaviour the most in MOH patients. Patients initially considered preventive treatment without withdrawal as the most feasible treatment. However, no difference in feasibility between the three arms was found at 6-month follow-up. Withdrawal combined with preventive medication is recommended for treatment of MOH.
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The nociceptive flexion reflex (NFR) is a spinal reflex induced by painful stimuli resulting in an appropriate withdrawal response. The NFR is considered to be an objective physiological correlate of spinal nociception. Previous research has already demonstrated that physical activity (PA) can influence pain assessments. To date, no studies have directly examined the relationship between PA and spinal nociception. Hence, this study aimed to investigate whether the NFR threshold can be predicted by report-based and monitor-based measures of PA in healthy adults. ⋯ The present study provides preliminary evidence that the influencing effects of physical activity on pain are the result of a strong descending control and do not purely rely on supraspinal mechanisms. These study results highlight the importance of considering physical activity levels when evaluating nociceptive processing, given the prognostic value of physical activity in spinal nociception. Furthermore, this study encourages future research to examine the effects of moderate- to vigorous-intensity exercise programmes on spinal nociception in chronic pain populations.
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Research among adult and paediatric samples suggests that pain-related injustice appraisals contribute to adverse pain-related functioning. However, a singular focus on pain-related injustice appraisals carries the risk of underestimating the role of broader concepts of justice. This study examined the unique roles of child pain-related injustice appraisals and just-world beliefs in understanding disability and physical, emotional, social and academic functioning, as well as the mediating role of injustice appraisals in the relationship between just-world beliefs and functioning. ⋯ The present study adds to emerging literature on the adverse effects of child pain-related injustice appraisals in the context of pain, through showing that pain-related injustice appraisals are uniquely associated with pain-related functioning and mediate the relationship between just-world beliefs and pain-related functioning. These findings suggest that interventions may target pain-related injustice appraisals as a mechanism for change in children.
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A noxious stimulus following a more intense stimulus often feels less painful than continuous noxious stimulation. This effect, known as offset analgesia (OA), may be due to descending inhibitory control, to changes in peripheral neural transmission or both. The timing and location of noxious thermal stimulation were manipulated to better understand the peripheral and central contributions to OA. ⋯ Offset analgesia (OA) is a fundamentally temporal phenomenon dependent on dynamic changes in stimulus intensity. Here we demonstrate increased OA with increased stimulus duration. This finding implies the more slowly-responding AMH-I peripheral mechanoreceptors contribute to OA. The more rapidly responding AMH-II peripheral mechanoreceptors, however, may be absent or more difficult to activate in the palm where we did not observe OA. This finding implies that the AMH-II receptors are necessary for OA. Our studies suggest methods to unravel the different peripheral and central contributions to OA.