Articles: hyperalgesia.
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Acta neurologica Belgica · Oct 2020
Association of dynamic and widespread mechanical sensitivity in cluster headache.
We investigated if dynamic pressure pain sensitivity in the symptomatic area is associated with pressure sensitivity in local and distant pain-free areas in cluster headache (CH). A pressure algometry set consisting of 8 rollers with fixed pressure levels ranging from 500 to 5300 g was used to assess dynamic pressure pain sensitivity in men with episodic CH. Each roller was moved from an anterior-to-posterior direction over the temporalis muscle. ⋯ Further, DPT, but not roller-evoked pain, was moderately associated with PPTs measured at the symptomatic (temporalis: r = 0.665, P < 0.001) and distant pain-free (C5-C6 joint: r = 0.389, P = 0.013; second metacarpal: r = 0.551, P < 0.001; and, tibialis anterior: r = 0.308, P = 0.035) points. Dynamic pressure sensitivity in the trigeminal area was correlated to pressure pain sensitivity at both symptomatic and distant pain-free areas in men with CH supporting the use of roller pressure algometry. Dynamic pressure algometry may be a new tool for assessing the status of sensitization in primary headaches.
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Understanding the mechanisms that drive transition from acute to chronic pain is essential to identify new therapeutic targets. The importance of endogenous resolution pathways acting as a "brake" to prevent development of chronic pain has been largely ignored. We examined the role of interleukin-10 (IL-10) in resolution of neuropathic pain induced by cisplatin. ⋯ Cisplatin treatment also depolarized the resting membrane potential, and decreased action potential voltage threshold and rheobase, while increasing ongoing activity at -45 mV and the amplitude of depolarizing spontaneous fluctuations. In vitro addition of IL-10 (10 ng/mL) reversed the effect of cisplatin on SA and on the depolarizing spontaneous fluctuation amplitudes, but unexpectedly had little effect on the other electrophysiological parameters affected by cisplatin. Collectively, our findings challenge the prevailing concept that IL-10 resolves pain solely by dampening neuroinflammation and demonstrate in a model of chemotherapy-induced neuropathic pain that endogenous IL-10 prevents transition to chronic pain by binding to IL-10 receptors on sensory neurons to regulate their activity.
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Consistency between back pain intensity and degenerative changes on magnetic resonance imaging (MRI) of the lumbar spine is poor. This study aimed to show whether tender point (TP) examination, used as a test for diffuse central sensitization, may add valuable information to clinical assessment of patients with low back pain (LBP). This was a cross-sectional study including 141 patients with LBP on sick leave. ⋯ Men with >7-8 TPs and women with >10-11 TPs had more back pain and similar or fewer degenerative changes than patients with few TPs (<3 and <6 TPs, respectively), thereby identifying 34% to 44% of patients with nonspecific LBP and 5% to 8% of patients with radiculopathy, respectively, with disproportionate back pain in relation to degenerative changes. Supplemental TP examination improved clinical and MRI evaluation of patients with LBP. By using gender-specific cut points, patients with disproportionate back pain were identified, presumably indicating diffuse central sensitization.
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Rheumatoid arthritis-associated pain is poorly managed, often persisting when joint inflammation is pharmacologically controlled. Comparably, in the mouse K/BxN serum-transfer model of inflammatory arthritis, hind paw nociceptive hypersensitivity occurs with ankle joint swelling (5 days after immunisation) persisting after swelling has resolved (25 days after immunisation). In this study, lipid mediator (LM) profiling of lumbar dorsal root ganglia (DRG), the site of sensory neuron cell bodies innervating the ankle joints, 5 days and 25 days after serum transfer demonstrated a shift in specialised proresolving LM profiles. ⋯ Unlike gabapentin, which was used as positive control, systemic MaR1 did not display acute antihyperalgesic action. Therefore, these data suggest that MaR1 effects observed after K/BxN serum transfer relate to modulation of macrophage recruitment, more likely than to direct actions on sensory neurons. Our study highlights that, in DRG, aberrant proresolution mechanisms play a key role in arthritis joint pain dissociated from joint swelling, opening novel approaches for rheumatoid arthritis pain treatment.