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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Idiopathic chronic pain conditions with a mismatch between anatomical abnormalities and symptoms can be categorized as somatoform pain disorder according to the DSM-IV criteria. A dysfunction of pain processing circuits has been suggested as one underlying pathophysiological factor. There is accumulating evidence for a crucial role of affect regulating brain structures such as the medial frontal cortex in this context. ⋯ The average ratings for experimentally induced pain were not significantly different between controls and patients concerning pain intensity and pain unpleasantness. Comparing patients with controls a pain related hypoactive state of the ventromedial prefrontal/orbitofrontal cortex (BA 10/11) and a hyperactive state of the parahippocampal gyrus, amygdala and anterior insula were found in the patient group. Our findings of an altered cerebral processing of experimentally induced pain in patients with somatoform pain disorder support the hypothesis of dysfunctional pain processing, especially in affect regulating regions.
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Randomized Controlled Trial Multicenter Study
Alvimopan, a peripherally acting mu-opioid receptor (PAM-OR) antagonist for the treatment of opioid-induced bowel dysfunction: results from a randomized, double-blind, placebo-controlled, dose-finding study in subjects taking opioids for chronic non-cancer pain.
Our objective was to investigate the efficacy and safety of alvimopan, a peripherally acting mu-opioid receptor (PAM-OR) antagonist, in subjects with non-cancer pain and opioid-induced bowel dysfunction (OBD), and to identify at least one treatment regimen that improves OBD. Following a 2-week baseline period, 522 subjects reporting <3 spontaneous bowel movements (SBMs)/week (with >or=25% accompanied by a sensation of incomplete evacuation, straining, or lumpy hard stools), requiring analgesia equivalent to >or=30 mg oral morphine/day were randomized to alvimopan 0.5mg twice daily (BID), 1mg once daily (QD), 1mg BID, or placebo for 6 weeks. Compared with placebo, there was a statistically and clinically significant increase in mean weekly SBM frequency over the initial 3 weeks of treatment (primary endpoint) with alvimopan 0.5mg BID (+1.71 mean SBMs/week), alvimopan 1mg QD (+1.64) and alvimopan 1mg BID (+2.52); P<0.001 for all comparisons. ⋯ The alvimopan 0.5mg BID regimen demonstrated the best benefit-to-risk profile for managing OBD with alvimopan in this study population, with a side effect profile similar to that of placebo. There was no evidence of opioid analgesia antagonism. Competitive peripheral antagonism of opioids with alvimopan can restore GI function and relieve OBD without compromising analgesia.
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Multicenter Study
A patient-based national survey on postoperative pain management in France reveals significant achievements and persistent challenges.
We carried out a national survey on postoperative pain (POP) management in a representative sample (public/private, teaching/non-teaching, size) of 76 surgical centers in France. Based on medical records and questionnaires, we evaluated adult patients 24h after surgery, concerning information: pre and postoperative pain, evaluation, treatment and side effects. A local consultant provided information about POP management. ⋯ Epidural (1.5%) and peripheral (4.7%) nerve blocks were under used. Evaluation (63.4%) or treatment (74.1%) protocols were not available for all patients. This national, prospective, patient-based, survey reveals both progress and persistent challenges in POP management.
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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.