Articles: hyperalgesia.
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Randomized Controlled Trial
Short-Term Effects of 10% Lidocaine Ointment on Allodynia in Cancer Pain: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study.
Background: There is currently no established therapy for allodynia, which is a type of neuropathic pain. However, high concentrations of topical anesthetics can anesthetize the skin and increase the sensory threshold to tactile stimulation. Objective: We aimed to evaluate the short-term effects and safety of 10% lidocaine ointment for treating allodynia in cancer pain. Design: This was a randomized double-blind crossover study comparing the efficacies of 10% lidocaine ointment and placebo ointment for the treatment of static allodynia and spontaneous pain within 24 hours after ointment application, using a numerical rating scale (NRS). Setting/Subjects: The subjects were 25 cancer patients with current pain rating of ≥4 on NRS of static allodynia in cancer pain. Results: The NRS scores for static allodynia were significantly lower in the lidocaine group than in the placebo group at two to eight hours after initial ointment application. ⋯ There was no interaction between time and group in terms of NRS values for spontaneous pain (p = 0.835), but a significant main effect of group was found, with NRS scores being significantly lower in the lidocaine group than in the placebo group (p = 0.027). There were no adverse events associated with lidocaine use. Conclusions: Lidocaine ointment 10% can alleviate allodynia for two to eight hours after application.
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Randomized Controlled Trial
A randomised, double blind, placebo-controlled crossover trial of the influence of the HCN channel blocker ivabradine in a healthy volunteer pain model: an enriched population trial.
Preclinical studies suggest that type 2 hyperpolarization-activated cyclic nucleotide gated ion channels (HCN2) are necessary for neuropathic pain. This trial assessed the influence of ivabradine, a nonselective HCN channel blocker, on capsaicin-induced hyperalgesia and pain in healthy human subjects. An enriched population comprising subjects who developed >20 cm of punctate hyperalgesia from topical capsaicin (0.5% cream applied onto 9 cm area) was identified. ⋯ However, ivabradine caused a slowing of heart rate (difference of 10.10 beats per minute [95% confidence interval -6.48 to -13.73; P-value <0.0001]). We conclude that ivabradine lacks analgesic effects in the capsaicin pain model at a dose that caused appreciable slowing of heart rate and, hence, is unlikely to prove a useful analgesic in humans. More selective drugs are required to establish a role of HCN2 for pain in humans.
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Delayed onset muscle soreness (DOMS) is characterized by mechanical hyperalgesia after lengthening contractions (LC). It is relatively common and causes disturbance for many people who require continuous exercise, yet its molecular and peripheral neural mechanisms are poorly understood. ⋯ Here, we show that not only C- but also Aδ-fibre nociceptors in the muscle are involved in mechanical hypersensitivity after lengthening contractions, and that acid-sensing ion channel (ASIC)-3 expressed in the thin-fibre nociceptors is responsible for the mechanical hypersensitivity. ASIC3 might be a novel pharmacological target for pain after exercise.
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Topical capsaicin is commonly employed to experimentally induce central sensitization (CS) in humans. While previous studies have investigated the effect of skin preheating on the sensitizing effect of capsaicin, no studies have compared the synergistic effect of skin preheating on the magnitude of sensitization via topical capsaicin within the first 30 minutes of application. We tested the hypothesis that skin preheating potentiates the sensitizing effect of topical capsaicin by evoking a larger region of secondary hyperalgesia vs. topical capsaicin alone. ⋯ Preheating amplifies the sensitizing effect of topical capsaicin within 30 minutes of application. The heat-capsaicin technique may be employed to assess differing magnitudes of CS induction and enables future studies investigating the development and progression of CS in humans.
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Anesthesia and analgesia · Oct 2019
The GCs-SGK1-ATP Signaling Pathway in Spinal Astrocytes Underlied Presurgical Anxiety-Induced Postsurgical Hyperalgesia.
Patients undergoing surgery often feel anxious. Accumulating evidence indicated that presurgical anxiety was related to the more severe postsurgical pain. An animal model was established that exposed Sprague-Dawley rats to a single-prolonged stress (SPS) procedure to induce presurgical anxiety-like behaviors. The experiment revealed that presurgical anxiety not only aggravated but also prolonged postsurgical pain. However, the underlying mechanisms were unknown. ⋯ These data suggested an important signaling pathway that affected the pain sensitivity after operation caused by presurgical anxiety.