Articles: neuralgia.
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This comprehensive review of pain in paraneoplastic neurological syndromes focuses on current mechanisms that lead to pain, including autoimmune processes as well as the systemic secretion of factors that sensitize nociceptive nerves. Systemic secretion of functional molecules is a well-recognized phenomenon in endocrine paraneoplastic syndromes; however, cancer pain research has predominantly focused on cytokine-nerve interactions in the tumor microenvironment, and few groups have applied the molecular mechanisms of local pain to study widespread neuropathic pain resulting from systemic secretion. We present a novel perspective in the field of pain research by converging data from clinical oncology with recent molecular pain research on cytokine-mediated sensitization of nociceptive nerves. ⋯ Paraneoplastic neurologic syndromes, chronic pain, neuropathic pain, treatment guidelines, cytokines.
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Accumulating evidence demonstrates the beneficial effects of physical exercise on pain conditions; however, the underlying mechanisms are not understood thoroughly. The purpose of the present study was to investigate the effects of regular swimming exercise on neuroma pain and the possible roles of adipokines (leptin and adiponectin) in the pain behaviors modulated by exercise. The results showed that 5 weeks of regular swimming exercise relieved pain behaviors in a rat model of neuroma pain and normalized the dysregulation of circulating leptin and adiponectin in plasma induced by nerve injury. ⋯ These findings indicate that leptin and adiponectin might be involved in mediating the beneficial effects of exercise on neuroma pain. PERSPECTIVE: Perspective: Identifying which endogenous processes are activated by specific exercise regimes would likely reveal novel therapeutic targets for the treatment of neuropathic pain. The current study suggests that adipokines might be involved in pain behaviors modulated by exercise and thus presents them as potential targets for pain management.
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Neuropathic pain is frequently driven by ectopic impulse discharge (ectopia) generated in injured peripheral afferent neurons. Observations in the spinal nerve ligation (SNL) model in rats suggest that cell bodies in the dorsal root ganglion (DRG) contribute 3 times more to the ectopic barrage than the site of nerve injury (neuroma). The DRG is therefore a prime interventional target for pain control. ⋯ Lidocaine applied to the cut spinal nerve end or the L4 DRG did not affect allodynia, suggesting that discharge originating in the neuroma and in neighboring "uninjured" afferents makes at best a minor contribution. Spike electrogenesis in the DRG is apparently the primary driver of tactile allodynia in the SNL model of neuropathic pain, and it can be controlled selectively by superfusing the relevant DRG(s) with nonblocking concentrations of lidocaine. This approach has potential clinical application in conditions such as postherpetic neuralgia and phantom limb pain in which one or only a few identifiable ganglia are implicated as pain drivers.
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Pain in Parkinson's disease (PD) is a common and heterogeneous non-motor symptom. Although the characteristics and predictors of pain in general and of central pain in particular are still largely unknown. ⋯ In a consecutive series of 292 patients with PD, almost three quarters of patients with PD reported pain. The study results revealed that pain was related to more severe motor symptoms, anxiety symptoms and comorbidities. Among patients with pain, those with central parkinsonian subtype had distinct demographic and clinical features, including lower levodopa responsiveness for non-axial motor symptoms and greater responsiveness of pain to antiparkinsonian treatment.
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Radicular pain is related to lesions that either directly compromise the dorsal root ganglion (DRG) or indirectly compromise the spinal nerve and its roots by causing ischemia or inflammation of the axons. ⋯ Outcomes after PRF at the DRG did not show strong differences according to electrodiagnostic findings in FBSS patients with chronic intractable lumbosacral radicular pain.