Articles: neuralgia.
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Neuropathic pain significantly reduces an individual's quality of life and places a significant economic burden on society. As such, many cost-effectiveness analyses (CEAs) have been published for treatments available for neuropathic pain. ⋯ Though many pulished studies have evaluated the cost-effectiveness of treatments for neuropathic pain, significant heterogeneity between CEAs prevented synthesis of the results. Standardized methodology and improved reporting would allow for more reliable comparisons across studies.
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While evidence indicates that sigma-1 receptors (Sig-1Rs) play an important role in the induction of peripheral neuropathic pain, there is limited understanding of the role that the neurosteroidogenic enzymes, which produce Sig-1R endogenous ligands, play during the development of neuropathic pain. We examined whether sciatic nerve injury upregulates the neurosteroidogenic enzymes, cytochrome P450c17 and 3β-hydroxysteroid dehydrogenase (3β-HSD), which modulate the expression and/or activation of Sig-1Rs leading to the development of peripheral neuropathic pain. Chronic constriction injury (CCI) of the sciatic nerve induced a significant increase in the expression of P450c17, but not 3β-HSD, in the ipsilateral lumbar spinal cord dorsal horn at postoperative day 3. ⋯ Co-administration of the Sig-1R agonist, PRE084 restored the development of mechanical allodynia originally suppressed by the ketoconazole administration. However, ketoconazole-induced inhibition of thermal hyperalgesia was not affected by co-administration of PRE084. Collectively these results demonstrate that early activation of P450c17 modulates the expression and activation of astrocyte Sig-1Rs, ultimately contributing to the development of mechanical allodynia induced by peripheral nerve injury.
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A rat model of neuropathic pain at 6 weeks after spinal nerve ligation (SNL6w) exhibits both mechanical hypersensitivity and impaired noxious stimuli-induced analgesia (NSIA). Repeated treatment with antidepressants can produce antihypersensitivity and restore NSIA. To examine the involvement of a brain-derived neurotrophic factor-mediated mechanism, a tropomyosin receptor kinase B (TrkB) agonist, 7,8-dihydroxyflavone (DHF), was administered to SNL6w rats (5 mg/kg/d for 5 days). ⋯ PERSPECTIVE: This article demonstrates that repeated treatment with TrkB agonist, DHF, restored endogenous analgesia. Repeated amitriptyline treatment showed similar effect via TrkB-mediated mechanisms, and the effect may be independent from the effect of antihypersensitivity. This effect of TrkB activation is promising for patients with chronic pain with impaired descending inhibition.
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Randomized Controlled Trial Comparative Study
Insular and anterior cingulate cortex deep stimulation for central neuropathic pain: Disassembling the percept of pain.
To compare the analgesic effects of stimulation of the anterior cingulate cortex (ACC) or the posterior superior insula (PSI) against sham deep (d) repetitive (r) transcranial magnetic stimulation (TMS) in patients with central neuropathic pain (CNP) after stroke or spinal cord injury in a randomized, double-blinded, sham-controlled, 3-arm parallel study. ⋯ NCT01932905.
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Background and aims Following spinal cord injury (SCI), a majority of individuals may develop neuropathic pain, which further reduces quality of life. Pain is difficult to treat by medication; in fact, medication overuse may aggravate neuropathic pain in SCI by causing central sensitization (CS): a mechanism of hyper-reactivity of the dorsal horn neurons in the spinal cord with amplified cerebral pain response. The purpose of this study was to examine the presence of neuropathic pain and CS above the spinal lesion in SCI, and to investigate whether injury characteristics or medication influenced pain response. ⋯ However, findings regarding SCI subgroup comparison did not support our hypothesis that more medication leads to increased CS. Implications The development of CS may complicate diagnosis and pain treatment following SCI. Prospective studies of SCI with a healthy control group are needed.