Pain
-
Offset analgesia (OA) is a form of endogenous pain inhibition characterized by a disproportionately large reduction in pain perception after a small decrease in temperature during noxious thermal stimulation. In this study, the presence of OA was evaluated in patients with fibromyalgia and compared with healthy age-matched and sex-matched controls. Offset analgesia was induced by noxious thermal stimulation on the arm, causing a visual analog score (VAS) of about 50 mm, followed by a 1°C temperature decrease. ⋯ Decreased OA responses were not enhanced or restored by repeating the OA paradigm or by the downward step test. Defective engagement of OA had a significant effect on pain onset, as observed from the upward OA step test, with less tolerability to noxious pain stimulation in patients with fibromyalgia. In conclusion, patients with fibromyalgia showed less pain inhibition as measured by the OA paradigm, which influenced both the onset and offset of pain.
-
Histamine plays a complex role in pain modulation with opposite roles in nociception for histamine receptor subtypes 1, 2, and 3. The histamine H4 receptor (H4R) is expressed primarily on cells involved in inflammation and immune responses with a proinflammatory activity, but little is known about the role in nociception of neuronal H4R. To investigate the effects of neuronal H4R in pain transmission, the effects produced by the H4R agonist ST-1006 were detected in the spared nerve injury model of neuropathic pain. ⋯ Double immunofluorescence experiments showed a neuronal localization and site of action for H4R. These findings suggest a prevalent modulation of ERK activity after H4R stimulation and indicate the DRG as prominent site of action for H4R-mediated antineuropathic activity. Targeting neuronal H4R with selective agonists could have therapeutic potential for neuropathic pain treatment.
-
Randomized Controlled Trial
Analgesic and sedative effects of perioperative gabapentin in total knee arthroplasty A randomized, double-blind, placebo-controlled, dose-finding study.
Gabapentin has shown acute postoperative analgesic effects, but the optimal dose and procedure-specific benefits vs harm have not been clarified. In this randomized, double-blind, placebo-controlled dose-finding study, 300 opioid-naive patients scheduled for total knee arthroplasty were randomized (1:1:1) to either gabapentin 1300 mg/d (group A), gabapentin 900 mg/d (group B), or placebo (group C) daily from 2 hours preoperatively to postoperative day 6 in addition to a standardized multimodal analgesic regime. The primary outcome was pain upon ambulation 24 hours after surgery, and the secondary outcome was sedation 6 hours after surgery. ⋯ Dizziness was more pronounced from days 2-6 in A vs C. More severe adverse reactions were observed in group A vs B and C. In conclusion, gabapentin may have a limited if any role in acute postoperative pain management of opioid-naive patients undergoing total knee arthroplasty and should not be recommended as a standard of care.
-
Randomized Controlled Trial Multicenter Study Comparative Study
Randomized, Double-Blind, Comparative-Effectiveness Study Comparing Pulsed Radiofrequency to Steroid Injections for Occipital Neuralgia or Migraine with Occipital Nerve Tenderness.
Occipital neuralgia (ON) is characterized by lancinating pain and tenderness overlying the occipital nerves. Both steroid injections and pulsed radiofrequency (PRF) are used to treat ON, but few clinical trials have evaluated efficacy, and no study has compared treatments. We performed a multicenter, randomized, double-blind, comparative-effectiveness study in 81 participants with ON or migraine with occipital nerve tenderness whose aim was to determine which treatment is superior. ⋯ Comparable benefits favoring PRF were obtained for worst occipital pain through 3 months (mean change from baseline -1.925 ± 3.204 vs -0.541 ± 2.644; P = 0.043), and average overall headache pain through 6 weeks (mean change from baseline -2.738 ± 2.753 vs -1.120 ± 2.1; P = 0.037). Adverse events were similar between groups, and few significant differences were noted for nonpain outcomes. We conclude that although PRF can provide greater pain relief for ON and migraine with occipital nerve tenderness than steroid injections, the superior analgesia may not be accompanied by comparable improvement on other outcome measures.