Pain
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Randomized Controlled Trial
Effects of intra-articular ketamine on pain and somatosensory function in temporomandibular joint arthralgia patients.
Recent studies have hypothesized that peripheral glutamate receptors could be implicated in deep craniofacial pain conditions. In this study 18 temporomandibular joint (TMJ) arthralgia patients received intra-articular injections of the N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine, or normal saline to study in a cross-over, double-blinded, placebo-controlled manner the effect on TMJ pain and somatosensory function. Spontaneous pain and pain on jaw function was scored by patients on 0-10 cm visual analogue scale (VAS) for up to 24h. ⋯ There were no significant effects of intra-articular ketamine over time on spontaneous VAS pain measures (ANOVA: P=0.532), pain on jaw opening (ANOVA: P=0.384), or any of the somatosensory measures (ANOVA: P>0.188). The poor effect of ketamine could be due to involvement of non-NMDA receptors in the pain mechanism and/or ongoing pain and central sensitization independent of peripheral nociceptive input. In conclusion, there appears to be no rationale to use intra-articular ketamine injections in TMJ arthralgia patients, and peripheral NMDA receptors may play a minor role in the pathophysiology of this disorder.
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Despite the frequent use of pain recall ratings in clinical research, there remains doubt about the ability of individuals to accurately recall their pain. In particular, previous research indicates the possibility that the most pain experienced during a recall period and the most recent pain experienced (known as peak and end effects, respectively) might bias recall ratings. ⋯ Also, the influence of peak pain was stronger than that of end pain. However, the biasing impact of both peak and end pain together was very small, suggesting that 24-h recall ratings are adequately valid indicants of average pain for patients participating in post-surgery clinical pain trials.
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Windup is a progressive, frequency-dependent increase in the excitability of trigeminal and spinal dorsal horn wide dynamic range (WDR) nociceptive neurons to repetitive stimulation of primary afferent nociceptive C-fibers. Superficial dorsal horn neurokinin 1 receptor (NK1R)-expressing neurons were recently shown to regulate sensitization of WDR nociceptive neurons through activation of a defined spino-bulbo-spinal loop. However, the windup of WDR nociceptive neurons was not regulated through this loop. ⋯ Second, we anatomically identified in the MDH lamina III a subpopulation of NK1R-expressing local interneurons that relay nociceptive information from the MDH to downstream Sp5O neurons. Third, using microinjections of NK1R antagonists during in vivo electrophysiological recordings from Sp5O WDR neurons, we showed that WDR neuron windup depends on activation of NK1Rs located in the MDH laminae I-III. We conclude that, in contrast to central sensitization that is controlled by a spino-bulbo-spinal loop, Sp5O WDR neuron windup is regulated through a local circuit activated by MDH lamina III NK1Rs.
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Randomized Controlled Trial Multicenter Study
Laser acupuncture in children with headache: a double-blind, randomized, bicenter, placebo-controlled trial.
To investigate whether laser acupuncture is efficacious in children with headache and if active laser treatment is superior to placebo laser treatment in a prospective, randomized, double-blind, placebo-controlled trial of low level laser acupuncture in 43 children (mean age (SD) 12.3 (+/-2.6) years) with headache (either migraine (22 patients) or tension type headache (21 patients)). Patients were randomized to receive a course of 4 treatments over 4 weeks with either active or placebo laser. The treatment was highly individualised based on criteria of Traditional Chinese medicine (TCM). ⋯ The mean number of headaches per month decreased significantly by 6.4 days in the treated group (p<0.001) and by 1.0 days in the placebo group (p=0.22). Secondary outcome measures headache severity and monthly hours with headache decreased as well significantly at all time points compared to baseline (p<0.001) and were as well significantly lower than those of the placebo group at all time points (p<0.001). We conclude that laser acupuncture can provide a significant benefit for children with headache with active laser treatment being clearly more effective than placebo laser treatment.