Pain
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Randomized Controlled Trial Multicenter Study Clinical Trial
Pain and analgesic response after third molar extraction and other postsurgical pain.
There is uncertainty over whether the patient group in which acute pain studies are conducted (pain model) has any influence on the estimate of analgesic efficacy. Data from four recently updated systematic reviews of aspirin 600/650 mg, paracetamol 600/650 mg, paracetamol 1000 mg and ibuprofen 400 mg were used to investigate the influence of pain model. Area under the pain relief versus time curve equivalent to at least 50% maximum pain relief over 6 h was used as the outcome measure. ⋯ The event rate with placebo was systematically statistically lower for dental than postsurgical pain for all four treatments. Event rates with analgesics, RB and NNT were infrequently different between the pain models. Systematic difference in the estimate of analgesic efficacy between dental and postsurgical pain models remains unproven, and, on balance, no major difference is likely.
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Comparative Study
Disengagement from pain: the role of catastrophic thinking about pain.
This paper reports an experimental investigation of attentional engagement to and disengagement from pain. Thirty-seven pain-free volunteers performed a cueing task in which they were instructed to respond to visual target stimuli, i.e. the words 'pain' and 'tone'. Targets were preceded by pain stimuli or tone stimuli as cues. ⋯ However, we also found that participants high in pain catastrophizing had difficulty disengaging from pain, whereas participants low in pain catastrophizing showed no retarded disengagement from pain. Our results provide further evidence that catastrophic thinking enhances the attentional demand of pain, particularly resulting in difficulty disengaging from pain. The clinical implications of these findings are discussed.
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Vulvar vestibulitis syndrome (VVS) is a common cause of dyspareunia in pre-menopausal women. Previous quantitative sensory test (QST) studies have demonstrated reduced vestibular pain thresholds in these patients. Here we try to find whether QST findings correlate to disease severity. ⋯ This test had the highest kappa value (0.82), predicting correctly 88% of all VVS cases and 100% of the severe VVS cases. Supra-threshold pain magnitude estimation for tonic heat stimulation also had a high kappa value (0.73) predicting correctly 82% overall with a 100% correct diagnosis of the control group. QST techniques, both threshold and supra-threshold measurements, seem to be capable of discriminating level of severity of this clinical pain syndrome.
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Botulinum toxin type A (BoNT-A) produced by the bacterium Clostridium botulinum is a potent inhibitor of acetylcholine release in the neuromuscular junction and has been used to treat many disorders related to excessive muscle contraction. However, BoNT-A has recently been used in pain therapy to treat myofascial pain, low back pain and various types of headaches, including migraine. The purpose of this study is to investigate the antinociceptive effect of BoNT-A and its underlying mechanism in the rat formalin inflammatory pain model. ⋯ Pre-treatment of rats with BoNT-A (3.5, 7 or 15 U/kg) all significantly reduced formalin-evoked glutamate (Glu) release. These results demonstrate that local peripheral injection of BoNT-A significantly reduces formalin-induced nociceptive behaviors with the absence of obvious muscle weakness. Such an antinociceptive effect of BoNT-A is associated with the inhibition of formalin-induced release of Glu (and/or neuropeptides) from primary afferent terminals.
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Comparative Study
Phantom phenomena in mastectomized patients and their relation to chronic and acute pre-mastectomy pain.
Chronic and acute pre-mastectomy pain as well as prevalence and characteristics of phantom phenomena following mastectomy were investigated by interview in a sample of 39 women who had undergone unilateral breast amputation. Twenty of 39 participants reported phantom sensations in the breast. Nine of the participants with phantom sensations experienced phantom pain and 11 non-painful phantom sensations. ⋯ This difference may be explained by the absence of kinesthesis and the small representation of the human breast. Seven of the 39 participants experienced chronic and six acute breast pain prior to the amputation. The amount of chronic pre-mastectomy breast pain weighted by the amount of involved tissue was significantly higher among participants with non-painful phantom sensations, compared to women with painful phantoms and those without phantom phenomena.