Articles: hyperalgesia.
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Intra-articular hyaluronic acid (HA) injection, known as viscosupplementation, is a widely used therapy for pain relief in knee osteoarthritis (OA). Long-term clinical efficacy of HA has been reported in spite of a relatively short residence time. Herein, we evaluated our hypothesis that intra-articular HA injection could reduce the OA-associated changes in joint afferents. ⋯ Intra-articular HA injections reduced the severity of OA, decreased mechanical hyperalgesia of the paw, but not weight-bearing asymmetry, and attenuated OA-associated up-regulation of CGRP, but not TrkA and ASIC3, in joint afferents. The modulatory effects of HA on joint afferents is one of the underlying mechanisms of the gap between HA residence time and duration of clinical efficacy.
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Transcutaneous electrical nerve stimulation (TENS) is a non-invasive analgesic resource extensively used in painful conditions. However, preclinical studies suggest that the prolonged use of TENS results in the development of tolerance to its analgesic effect. The present study investigated the analgesic effect and development of tolerance to TENS with four different stimulation protocols. ⋯ The association between frequency variation and intensity at motor level promotes a delay in the development of analgesic tolerance to TENS, optimizing and extending its therapeutic effectiveness.
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Muscle hyperalgesia is typically evaluated by pressure algometry applying linear stimulation. Combining linear pressure stimulation with additional minor variations of the pressure in different directions may optimize the detection of pain sensitivity in hyperalgesic muscle. ⋯ Rotational stimulation together with pressure stimulation was more efficient than classical pressure algometry in detecting muscle hyperalgesia.
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Lumbopelvic pain is common in pregnancy but the sensitization factors underlying the condition are largely unknown. This study characterized the somatosensory profile of pregnant and nonpregnant women and the relationship between pain, hypersensitivity, and commonly used manual clinical tests. Thirty-nine pregnant and 22 nonpregnant women were included. Although lumbopelvic pain was not an inclusion criterion, the pregnant women were divided into low- and high-pain groups following data collection. The sensitivity to light brush, pin-prick, and pressure pain was assessed bilaterally at 3 sites in the lumbopelvic region, at the shoulder, and in the lower leg. Responses to the active straight leg raise test and pain provocation tests of the sacroiliac joint were recorded. Participants completed questionnaires addressing emotional and physical well-being and rated disability using the Pelvic Girdle Questionnaire. Compared with controls, the high-pain group rated the active straight leg raise test as more difficult (P < .05), and both pain groups had more positive pain provocation tests (P < .05). The pregnant groups demonstrated significantly lower pressure pain thresholds at most assessment sites compared with controls (P < .05), but self-reported disability and pain were not correlated with pressure pain thresholds within pregnant participants. The high-pain group reported worse emotional health and poorer sleep quality than controls (P < .05). ⋯ This article presents the somatosensory profile of a healthy pregnant cohort. The results indicate that pain sensitivity increases during pregnancy possibly owing to the physical changes the body undergoes during pregnancy but also owing to changes in emotional health. This should be accounted for in clinical management of pregnant women with lumbopelvic pain.
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Primary and metastatic cancers that affect bones are frequently associated with severe and intractable pain. The mechanisms underlying the development of bone cancer pain are largely unknown. In the present study, we investigated whether inhibition of KCNQ/M (Kv7) potassium channels in the spinal cord contributes to the development of bone cancer pain via sensitization of dorsal horn wide dynamic range (WDR) neurons. ⋯ Furthermore, we discovered that blockade of KCNQ/M channels in the spinal cord by local administration of XE-991, a specific KCNQ/M channel blocker, caused a robust increase in excitability of dorsal horn WDR neurons, while, producing obvious pain hypersensitivity in normal rats. On the contrary, activation of spinal KCNQ/M channels by retigabine, a selective KCNQ/M channel opener, not only inhibited the bone cancer‑induced hyperexcitability of dorsal horn WDR neurons, but also alleviated mechanical allodynia and thermal hyperalgesia in the bone cancer rats, while all of these effects of retigabine could be blocked by KCNQ/M-channel antagonist XE-991. All things considered, these results suggest that suppression of KCNQ/M channels in the spinal cord likely contributes to the development of bone cancer pain via sensitization of dorsal horn WDR neurons in rats following tumor cell inoculation.